Combi Boiler. System Drainage.

Occasionally it may be necessary to drain down a combi boiler and central heating system. This may be to facilitate maintenance procedures, cleaning the system or the addition of extra radiators.

The process is relatively simple, but prior to attempting to drain a system, it is advisable to ensure that the person carrying out the draining also knows how to re-fill, add inhibitor and pressurise the system once the work has been carried out.

The method of pressurising of a combi boiler system varies between model and manufacturer. Instructions for pressurising may be found in the boiler user’s manual.

It is important to note that if the actual boiler requires draining, this must only be carried out by a competent person. Draining a combi boiler system does not involve draining the internal part of the boiler.

Before draining the combi boiler system it is important to ensure that the mains electricity supply to the boiler and any system programmers are turned off. This is to prevent the boiler operating with an empty system, which could seriously damage the boiler.

It is not necessary to turn off the mains water supply when draining a combi boiler system.

To drain the central heating system, first, locate the drain tap. This will be on the ground floor or the lowest point of the system. Occasionally it will be conveniently located at the end of a leg of pipe leading from a radiator to the outside of the property. If not, a length of hose will need to be attached to the spigot and run to the outside of the property or to a ground level drain entrance.

With the drain tap opened, water should start to flow out of the system. This flow will need to be supported by opening up the bleed valves on all the radiators attached to the system, starting at the top of the property or the radiator furthest from the drainage tap. Air entering the system will replace the vacating central heating fluid.

With the system drained, now is a good time to flush through the central heating system to remove debris. This is best accomplished by engaging the services of a specialist company, however, some sludge and debris can be removed by operating the refilling device to allow water to flow through and out of the system. It will be necessary to close off the radiator bleed valves to facilitate the flushing through of upstairs radiators.

Once any maintenance work has been accomplished, the system can be refilled and pressurised.

Firstly, the drain tap should be closed off. It is then essential to go round all the radiators and close off the bleed valves using the radiator bleed key.

At this point, it is essential to add an inhibitor solution into the system. A good way to do this is to locate the plug at the top of one radiator. This plug will be at the opposite end to the bleed valve. Removing this screw threaded plug will reveal an opening into which the required amount of inhibitor can be added using a funnel or open-ended tube.

The correct amount of inhibitor required by the system can be calculated by using the information supplied with the inhibitor.
Do not forget to replace and firmly tighten the radiator plug after adding the inhibitor.

Water should now be allowed back into the system using the filling loop or the refilling device appropriate to the particular boiler. This may be a key type facility, which operates an internal valve system within the boiler.

As water re-enters the system, the pressure gauge on the boiler should start to register an increase in system pressure. If it does not, immediately close off the filling loop and check the entire central heating system for any leaks. It may be found that a bleed valve on a radiator has not been closed off correctly or some new work on the system is leaking.

When the pressure indicator on the boiler reads one bar, the filling loop should be turned off and all the radiators bled to remove trapped air in the system. The bleed valves on the radiators should be bled from the nearest radiator to the boiler along and up to the radiators upstairs, or the furthest from the boiler. It will be necessary to return to the boiler filling loop and re-fill the system after bleeding the air from each radiator.

With all the air removed from the system, the filling loop should be operated to pressurise the system up to the manufacturer’s recommended cold pressure operating level. This is usually between 0.5 and 1.5 bar.

Once the correct pressure is reached, the boiler power, the programmers, and the timers can be turned back on.

The boiler and central heating should now operate correctly. Any banging or loud gurgling sounds will indicate that air is still trapped within the system, as will any radiators that are hot at the base but cold at the top.

To remedy these situations, the radiators will need further bleeding to remove the trapped air.

To clean a combi boiler system, the process is similar to that described above.

First, drain down the system. Flush through with clean water. Refill with water and a suitable cleaning fluid such as Fernox. Re-pressurise the system and run for 48 hours. Drain down the system again. Flush through with clean water and refill the system with inhibitor. Finally, re-pressurise the system.

Before undertaking any DIY work on a combi boiler central heating system, it is advisable to check that the work will not invalidate any warranty on the boiler that might be in place.

DIY Plumbing and Pollution

One of the greatest eureka moments in human history was the discovery that many diseases were contracted by people drinking contaminated water supplies.

These horrible diseases plagued our early towns and cities and were compounded by the lack of sanitation and the fact that human activity created waste compounds that were not being correctly disposed of. Blood and waste products from animal slaughter, toxins and heavy metals produced by manufacturing processes and the faecal and food waste products from human habitation trickled through open street troughs and into the nearest river or watercourse. These same watercourses provided much of the drinking water the inhabitants who could not afford cheap ale were forced to drink.

Life expectancy was short and early childhood mortality was the norm.

Today, things are much different. Sewage and other foul water wastes are carefully directed along dedicated pipe networks to vast treatment plants. Here they are carefully treated to clean out most of the harmful components before they are allowed to enter streams, rivers and oceans.

Surface water from roofs and other surfaces are kept separate and, because of their relative cleanliness, directed straight into streams and other watercourses where they become diluted and rendered harmless.

All very notable and efficient. Or is it?

Unfortunately, too much material that should be sent into the sewage system for treatment is currently being wrongly directed into the surface water system. Although not entirely the cause of the problem, much of the blame is being placed at the door of over enthusiastic DIY operatives who incompetently plumb appliance’s wastewater discharge pipes into the wrong drain. Dishwashers, washing machines, baths and sinks, even toilets can inadvertently have their waste flushed into the wrong pipe.

This rise in DIY activity is believed to be one of the contributing factors. The proliferation of daytime TV DIY and house renovation programmes seems to have spurred an increase in inexperienced householders keen to save money by carrying out their own installations and home improvement work. This, coupled with the recession, which has deterred people from moving house and motivated them to alternatively embark on home improvement projects instead, has compounded the problem.

Today, the ease at which DIY appliances, fittings and other components and tools can be sourced, and the relatively cheap price of these items, has made DIY a leisure activity for many.

The recession has also meant that affording the services of qualified trades people has become increasingly beyond the financial means of many householders.

As a result, more and more effluent and other toxic substances are finding their way into the wrong drains and subsequently directly into the natural water systems.

DEFRA predicts that by 2017, over half a million properties in the UK will have misconnected and technically illegal drainage connections installed. Currently, in some areas, one in five households is known to have incorrectly plumbed drainage systems.

The damage caused to the environment is substantial. The decomposing material in rivers and seas removes oxygen from the water. This suffocates fish and encourages eutrophication, or the proliferation of algae, which forms dense blankets on water surfaces cutting out sunlight. Salmon, perch, pike and trout all succumb to this unnatural imbalance created by the disruption of normal environmental processes.

Toxic chemicals can cause undesirable mutations in wildlife. The endocrine disrupters released from contraceptive pills and flushed directly into clean watercourses can cause gender alterations in fish and other aquatic life.

However, not all problems are caused by hapless DIY operatives.

Too often toxic materials are deliberately discarded into drains, particularly street drains. Oil, antifreeze, and other motoring products are often flushed directly into them by inconsiderate vehicle owners.

The increase in the construction of external hardcover surfaces prevents natural drainage and following a rain downpour, water, and the debris collected on these surface gushes into storm drains, causing considerable pollution.

Not only is a polluted water course unattractive, the smell of decomposing organic material coupled with the myriad of unexpected chemical reactions that may occur can be quite unpleasant for neighbouring households.

So concerned are various environmental groups about this growing problem, that many are now monitoring watercourses to detect sewage contamination. Dyes can be added to pipe networks to discover the origins of contamination points.

Fly populations that inhabit waterside environments are being monitored to detect alterations in normal populations caused by trace contaminants. When detected, the Environment Agency is informed. The Agency is then obliged to carry out further investigations to try to determine the source of the problem before it becomes a serious issue.

The government has also set up the Connect Right campaign. This body provides information and advice to homeowners and developers about connecting appliances to the correct drainage system. It also provides links to accredited Water Safe plumbing engineers. These plumbers and fitters have the relevant experience and the technical understanding of environmental issues to ensure that any work is correctly undertaken.

Homeowners with older properties are also recommended to have their drainage systems regularly checked to ensure correct operation. Deterioration of older pipe-work can cause seepage of contaminants into the wider environment causing harm to wildlife and human populations alike.

For homeowners and DIY enthusiasts, taking care to ensure that drainage systems are correctly identified prior to embarking on installations will help to reduce the problems associated with incorrect connection issues.

Where any plumbing work lies beyond the scope or experience of the householder, employing a professional and competent plumber will ensure that our natural habitats remain as unaffected by human activity as is possible.

Hot Water Airlocks in Indirect Systems


Air trapped in the water supply pipework can cause homeowners considerable inconvenience, particularly when it becomes a recurrent problem. Central heating airlocks are generally easy to resolve and may simply require the bleeding of radiators.

When the air becomes trapped in the domestic hot water supply, dealing with it can become a little more complex.

The presence of low pressure at a hot water outlet may be caused by a number of problems. If the problem seems to be restricted to one outlet, it may be worth checking to see whether a filter is incorporated in the tap or device. Filters in tap fittings occasionally become blocked with limescale and other debris or mineral deposits. The filters can be removed and cleaned.

In old hot taps, damaged washers or excessive wear and tear can lead to flow problems. Older taps are better replaced with newer ones.

Internal filters in shower devices, particularly electric ones, are a specialist task and should be serviced by a competent person.

Where low hot water pressure occurs frequently, with or without air locking problems, it is important to check whether the mains supply to the water storage tank in the loft is sufficient. It might also be necessary to check the tank’s capacity to ensure it is sufficient to meet demand. Where water flows out of the tank faster than it can be replaced, the potential for air to enter the system is greatly increased.

Blockages can also occur in ball valves that restrict the flow of mains water into the tank. To check mains pressure at the ball valve, place a finger over the valve outlet and press down the ball cock. It will be impossible to prevent good mains pressure water from escaping around a finger. A blocked valve should be cleaned.

Airlocks may also occur if a storage tank runs dry when the mains water supply is interrupted, for instance due to a provider carrying out maintenance work on their system.

Where the mains supply is sufficient and yet all the hot taps are experiencing low or non-existent flow rates, an airlock in the system is the likely cause.

There are a number of ways to try to remove an airlock. If the mains water supply is delivered by a single cold-water tap at the kitchen sink, it is possible to firmly attach a length of hose from the spout of the cold tap to the spout of the hot tap. With the hot tap turned on, the cold tap should be gradually opened. Cold water at mains pressure will flow into the hot water system forcing any air through the system and back into the cold-water storage tank in the loft. The cold water should only need to flow for a few seconds to clear the pipes.

If the tap at the sink is a mixer type, it may be possible to cover the outlet spout with one hand. Then, with the other hand turn on the hot tap followed by the cold tap. Water will be forced from the cold into the hot tap completing the process outlined in the above method. A short length of hosepipe firmly attached to the spout and with both taps open can offer an alternative to using a hand. With the cold water flowing, tightly nip the hosepipe. This will force cold water into the hot water system.

On some mixer taps, non-return valves are installed internally to prevent backflow occurring. If this is the case, the above method will not work. However, an alternative method can be used. If a washing machine is installed and connected by hot and cold separate pipes, it is possible to turn off the supply valves to the hoses, disconnect them from the machine, join them together and turn on the hot, and then cold supply valves. Provided that the cold supply is at mains pressure, the cold water will force itself through the hot water system, hopefully taking the airlock with it. The supply pipes can then be reattached to the washing machine.

If these methods fail to remove the airlock, a final method is to turn off a suitable hot tap at its isolation point. This is usually a small valve located on the pipework supplying it. It is then necessary to dismantle the tap to a point where it is possible to attach a length of hosepipe. The other end must be attached securely to a cold tap supplying mains pressure. With the hot tap isolation valve open, turn on the cold supply and allow the cold water to enter the hot water system and flush out the airlock into the main storage tank. Once this is accomplished, turn off the main water tap. Close the hot tap isolation valve and reassemble the tap.

It is a good idea to have an observer stationed at the water tank in the loft with any of these methods to confirm successful operation and to warn of any danger of the tank overflowing during the process.

Repeated airlocks can sometimes be caused by air being pulled back into the system through the water expansion pipe. It is worth getting someone to go into the loft and cover the expansion vent pipe exit with their hand. At the same time have someone turn on the lowest hot tap on the circuit. This can force trapped air out of the system.

If these methods fail, it may be necessary to drain down the entire domestic hot water system.

First, ensure that the boiler and all pumps etc are turned off. Turn off the water feed to the storage tank. Then open all the hot taps to drain down the system. If any sludge is visible in the bottom of the tank, avoid allowing this material to be drawn down into the pipe-work. Sludge should be removed with a suitable scoop and bucket and the tank disconnected and cleaned correctly.

Once the system has drained, go round and close each hot tap until they are about three-quarters closed. Now turn the water supply to the storage tank back on. The tank will start to fill and eventually all the taps should have a gentle flow of water. Adjust each tap slightly so that the flow rate through each is similar. Starting with the lowest in the system, work upwards with each hot tap, turning them on further about half a turn. Return to the first tap and repeat the process again. Keep doing this until all the hot taps are fully turned on and all the air has been removed. The next step is to slowly turn them off until each tap has just a trickle. Let them run for a minute or so and then turn them all off. Do not forget to restart the boiler and any associated pumps when the task is completed. If the water pressure is particularly low, it may be necessary to fill the storage tank prior to operating the taps.

If this does not solve the problem, it is time to call in a professional to ensure that the problem does not lie elsewhere within the system.




Plumbing-In a Washing Machine or Dishwasher

With today’s easily obtainable plumbing supplies and fittings, plumbing a new washing machine or dishwasher is a relatively straightforward operation. Simple installations are well within the capabilities of any competent DIY enthusiast. Installations that are more complex may need the assistance of a general handyman or plumber to ensure that pipe fittings are correctly incorporated to allow the appliance to function reliably.

Perhaps the simplest installation is the replacement of an existing appliance with a new one. So long as the electricity plug has been removed from its socket, the water in-line supply valve turned off, the hose(s) unscrewed and the waste pipe disconnected; the old appliance can be eased from its existing position and disposed of.

In the case of a new washing machine, first, remove all packaging and either keep it in case it may be required again, or dispose of it. The main thing is to get it out of the way. Then, and with reference to the manufacturer’s installation instructions, the drum transit restraining bolts must be removed completely from the machine. These bolts prevent the drum from moving on its axle during transport. Failure to remove the bolts before operating the machine will seriously damage it. Keep these bolts safe in case it becomes necessary to transport the machine in the future.

To prevent unbalanced drum operation, the machine must be level. This can be achieved using a spirit level whilst adjusting the machine feet. The machine must also be stable and not able to rock when operating. The feet should also be adjusted to ensure that the machine will fit comfortably below any work surfaces.

Modern washing machines now have a single water connection hose. This has a fitting coloured blue and should be screwed onto the cold water supply fitting. This fitting should only be tightened by hand. The drainage and electrical fittings should all fit into the old connections with no need for modification. The new washing machine can then be slid into the existing space, taking care not to kink any of the pipes whilst doing so. The water supply can then be turned back on at the inline valve. Prior to switching on the electrical supply, it is a good idea to ensure that the operating switch on the machine is turned off otherwise the machine door will automatically lock when the power is supplied.

The manufacturer’s instructions will probably recommend running the machine empty on a hot wash prior to attempting to wash any fabrics. During the first operation, it is a wise precaution to monitor the machine and connections for any problems that might arise.

Installing a replacement dishwasher follows the same procedure; however, there are no transit bolts to remove. The machine must be level to ensure effective dish washing operation. Fittings are generally identical the previous installation.

To provide installation points for a new washing machine or dishwasher, slightly more complex plumbing procedures are required; however, it is possible to obtain all the necessary parts in a kit from major DIY outlets.

The first thing to consider is where to position the appliance. Not all appliances have to be located in the kitchen. Some homeowners prefer to locate appliances, particularly washing machines, in garages or conservatories. However, consideration must be given to frost protection.

Dishwashers tend to be located in the kitchen due to the frequency of operation and for convenience.

What both appliances require are a power source and water and waste connections. For that reason, both appliances tend to be located in the kitchen close to the sink where access to a cold water supply and drainage is readily available. In all probability, an electric socket will also be on hand to plug the appliance into.

To make a water connection to a cold pipe, first, isolate the pipe area or turn off the rising main. Drain the system as much as possible and then cut out a section of the supply pipe to accommodate a T fitting. All fittings should be either soldered or compression joints, depending on preference. An adequate length of pipe should be fitted into the T with an isolation valve to cut off the water supply in the event of a hose failure. A suitable connector should then be fixed to the end of the pipe to accommodate the machine hose. Incorporating a check valve should also be considered.

It is possible to obtain self-boring fittings that simply screw into existing pipework. These should be securely attached to a wall and in the off position prior to operating the self-tapping valve. It is also advisable to check with the water supplier that these fittings are permitted.

To fit a waste drainage connection firstly check the appliance manufacturer’s recommendations to ensure that a suitable outlet will be provided. The most common outlet consists of a vertical pipe with a minimum 40 mm diameter. This vertical pipe must have its top opening high enough to prevent any back-flow of water into the machine. This can be plumbed into the sink waste pipe with a suitable connection. The top of the pipe accommodates the machine waste pipe that simply hooks onto it. It is possible for two machine drainage pipes to be hooked onto this down pipe but it might not be advisable to have both machines draining at the same time.

Alternatively, a dedicated drainage fitting can be installed directly into the sink drainage system just above the trap. This fitting usually has two branches to accommodate two appliance drain hoses. Prior to fitting the drain hoses, blocking caps, either fitted internally or externally on each branch must be removed. In some instances, they may need to be sawn off.

To fit either appliance in a garage or alternative position, it will be necessary to provide independent water and drainage supply pipes. Although this can be straightforward if services are within easy access, providing these points may require professional intervention, particularly where new electrical installations will be required.

In general, installing a washing machine or dishwasher can be carried out without the need to employ a professional plumbing engineer.

Water Damage Due to Plumbing Issues

Water damage as a result of freak weather conditions can be very difficult to predict and prevent. Heavy rain and the resulting flooding can catch out even the best prepared, causing considerable damage and disruption to homes and businesses alike. The resources required to prevent flooding caused by natural events are mostly beyond the reach of individual homeowners and businesses.

Domestic plumbing failures can be equally catastrophic, causing misery and financial problems for the households in which they occur. Water can be particularly destructive. Water damaged goods and appliances can rarely be saved and must be discarded and replaced. Personal belongings with sentimental and irreplaceable significance can be lost forever.

One of the biggest hurdles to overcome after severe water damage is trying to dry out the water soaked building fabric. Air is essential in the drying out process. Where the air is absent or drying takes too long, microbial action produces unpleasant odours, which are very difficult to get rid of. Waterlogged carpets and water seepage under lino or wood laminate floorings make them particularly susceptible to such deterioration. Walls and plaster will also crumble and boarding will warp and distort. Severe water damage requires professional attention.

Apart from natural causes, water damage can be caused by burst pipes and leaks from appliances. These leaks usually occur as a result of poor workmanship, accidental damage or just normal, but un-noticed, wear and tear.

When a leak occurs, the severity of the damage is often compounded by a lack of awareness by householders of the location of the mains stopcock and how to use it. Around fifteen litres of water per minute will gush from a severed mains pipe. Any delay in closing off the water supply can be disastrous.

Washing machine hoses are high on the list of failures resulting in insurance claims for water damage. Although the hoses are designed to last around ten years, they should be frequently inspected for signs of deterioration. Any visible cracks or hardening of the rubber should cause concern and the hoses should be replaced. Some washing machine manufacturers advise replacing hoses every two years. Many homeowners turn off the isolation valves supplying water to the hose connections between each use of the washing machine as an added precaution. However, this may not always be practical and is dependent on ease of access.

Dishwasher hoses and draining pipes require similar inspection, as do the door seals around both appliances.

Old pipes, particularly galvanised ones, corrode over time. Galvanised pipes were used widely up until the 1970′s but are rarely used in domestic property now. They have an expected working lifespan of about thirty years, so if your property still has them it might be a good idea to replace them before problems occur.

Accidental damage frequently happens to pipe work, particularly when it is concealed within walls and beneath floorboards. It is very easy to inadvertently puncture a pipe when hammering a nail into a wall or wooden floor. Occasionally the punctured pipe can go unnoticed for some time, slowly leaking water into its surroundings and causing considerable unseen damage.

Water damage caused by poor plumbing practices and incompetent workmanship is often associated with DIY enthusiasts and their over ambitious projects. When attempting any plumbing work it is essential to familiarise yourself with the procedures and to ensure that all the necessary parts and tools are available. Failure to shut off the water supply prior to starting work is a big cause of water damage. Never cut corners or attempt to modify pipes and fittings beyond their original purpose. If in doubt, get a professional plumber in to do the work.

However, what might appear to be a professional plumber may not turn out to be one. Although it is a good idea to consider a plumber recommended by relatives and friends through word of mouth, never take on a plumbing engineer at face value. Always thoroughly check the credentials of a plumber. Ideally, they should belong to a recognised trade body, such as The Association of Plumbers and Heating Contractors. Being a member of such a body can give added protection should the plumber’s work be called into question. Do background checks on the plumber to establish the authenticity of the business and the length of time the business has been trading.

Remember to ensure that the plumber has adequate Public Liability Insurance. Insist on seeing proof of it prior to engaging their services. Remember that in the absence of suitable insurance, you are vicariously liable for third party damage if things go wrong. Having to claim for damage on your own contents insurance can cause future premiums to rise considerably.

Getting a written contract reflecting the work requirements and timescale for completion is essential. The contract should also clearly state all terms and conditions. Do ensure that the terms and conditions do not contain any unfavourable clauses. It may seem a little over precautionary, but if things do go wrong and subsequent water damage occurs to your property, a written contract will be more secure than a verbal one when seeking compensation. In dealing with a plumber, or any tradesperson, what might have been said cannot be verified. When it is written in black and white and signed by both parties, unless the wording is ambiguous, the contract is binding.

A good plumber will always produce workmanship to the satisfaction of a client. If things go wrong, first take the matter up with the plumbing engineers and give them a chance to rectify the situation. Where damage has occurred, their insurance will cover the cost of putting right the damage.

Always take photographs or videos of work in progress, damage or any evident faulty or questionable plumbing practices. These will be of great importance should you ever need to pursue a rogue tradesman through the small claims court.

Remember that if a plumbing and heating contractor is engaged to carry out gas work on a gas appliance, they must be registered with Gas Safe and competent to undertake the particular work. Always check that the ID card and photo match the engineer.

Water damage caused by plumbing issues may not be entirely preventable, but can be minimised by taking adequate precautions. There are devices that will produce an audible alarm if leaking water is detected. Some of these are simply strips of water sensitive electronics, which are often self-contained and simple to install. Other more sophisticated devices can be installed inline on the water pipe and will detect abnormal or extended water flow patterns. They then activate to turn off the water, limiting damage.

No householder likes to have to deal with water damage caused by plumbing issues. With a little forethought, the chances of such issues occurring are substantially reduced. Knowing how to deal with them if they should occur will help to make the procedure a little less disheartening.


Backflow in Plumbing

Clean, wholesome drinking water. We can take it for granted. Turn on the cold-water tap and it is there.

Wastewater. The grey soup from washing machines, washbasins, baths, and showers. It disappears down sinks and drains never to be seen again.

It would seem quite important that the two should never be allowed to mix and be inadvertently consumed by members of the household, or indeed other unsuspecting households connected to the supply.

Yet without precautions, clean water can become contaminated with materials that can have serious implications for human health. Toxic chemicals and dangerous micro-organisms can infiltrate domestic water supplies if suitable barriers are not in place to prevent them doing so.

The importance of maintaining an effective barrier between clean (potable) drinking water and the water using devices and appliances connected to the mains supply within the home should not be under-estimated. There are thousands of domestic water contamination incidents recorded each year, with some resulting in fatalities.

The biggest cause of problems involving domestic potable water contamination results from cross-connection issues. A contaminated source of water has the potential to be drawn into the clean water supply when it is connected to it. For example, a garden hose connected to the water supply could create a cross connection. If the flow of water through the connected hose is induced in the opposite direction this is referred to as backflow.

There are numerous cross connection unions in the typical home, from dishwashers and washing machines to combi boilers and mixer taps.

Backflow can be initiated by a number of adverse conditions such as a burst water main causing a sudden drop in pressure, a high demand for water on a supply line or frozen pipes interfering with the flow.

There are two main types of backflow. Siphonage and backpressure.

Siphonage may occur when the pressure of the mains water is not great enough to overcome the tendency for water to flow to its lowest level. For example, when siphoning a liquid from one container to another, a vacuum is created within the siphon tube by removing the air. So long as the siphon tube exit is positioned at a lower level than the level of the siphon tube entrance, the liquid will flow to its lowest level. This facilitates the flow of the liquid from one container to another.

Likewise, a garden hose with one end attached to the mains water supply and the other left submerged in a garden pond has the potential to contaminate the mains supply by the process of siphonage.

Backpressure is caused where the pressure in a system connected to the mains supply is able to overcome the mains pressure supplying it. For example, when water is heated by a combi boiler the water expands. As a result, the increased pressure has the potential to overcome the mains water pressure and cause a reversal of flow back into the mains water system. The same thing has the potential to occur with central heating fluids if the filling loop is left in place in the absence of a backflow prevention device.

The Water Supply (Water Fittings) Regulations 1999 makes the fitting of backflow prevention devices and techniques mandatory. The regulations also make it incumbent on the homeowner or a competent engineer, to install and maintain systems to comply with the regulations. They must prevent contamination and also give notice to the local council of any installation work that falls under The Buildings Regulations notification requirements.

The type of prevention device or method that must be employed can be established by referring to the list of water categories set out in the regulations. This list categorises the seriousness of contamination fluid risk on a score of one to five, with five being the most serious.

The simplest method of backflow prevention is to create an air gap. This is very effective and can be seen in operation with kitchen taps, sink taps, and toilet cisterns. The distance provided by the air gap is determined by the risk as set out in the regulations.

A tundish can also act as a backflow prevention device by virtue of the air gap it produces.

For direct connection, and in compliance with the necessary precautions determined by the Act, check valves, either single or double provide an effective barrier against potential contamination risks. These are easily fitted into the pipe-work where connections are made. A garden tap is required to be fitted with a check valve between a hose connection point and the tap bib.

Other forms of backflow prevention include ball valves in water storage tanks, where the water outlet must be above any overflow outlet, and integral protectors, such as are often found in mixer taps and non-return valves.

Reduced pressure zone valves (RPZ) may also be installed where required, but must be installed by a competent person.

Although it is not always necessary to fit check valves on mixer taps that do not have integral protectors, it is advisable.

It is also important to remember that tap outlets are a prime source of contamination and should be regularly cleaned. It is not uncommon to see contaminated material being placed in contact with the outlet or splashing back into it. Microbiological contaminants can thrive on tap outlets and contaminate further supplies.

When purchasing fittings it is important to ensure that they comply with the Water Regulations. It is not illegal to sell fittings that do not comply, but it is illegal to fit them.

The Act also stipulates that any fittings are installed in such a manner that they are easily accessible for maintenance and are adequately protected against frost.

The Water Regulations Advisory Scheme (WRAS) can provide copies of the Water Regulations (Water Fittings) Act 1999 and provide advice regarding compliance and the suitability of fittings.

Pipe Freezing Kits and Machines

Sometimes it can be the simplest job, such as changing a tap washer. At other times, it can be something slightly more complex, perhaps changing a radiator valve. Whatever the task, the thought of having to mess around trying to turn off a seized mains stopcock or drain down a central heating system, can initiate a certain amount of procrastination.

At other times, an urgency such as the repair of a burst pipe might be frustrated by the inability to locate either the domestic or the water provider’s main stopcock.

Whichever, the process of freezing and creating a plug of water in the supply pipework to temporarily interrupt the flow can be a quick and efficient method of facilitating a plumbing procedure.

Using a pipe freezing process is ideal for cutting the water supply in the immediate area to allow for the plumbing of T-pieces for appliances, radiator valve changes, pump and zone valve replacements. It can even facilitate the repair or replacement of a seized mains stopcock.

Pipe freezing can be accomplished by using refrigerants provided by disposable aerosol canisters or by specialised, electrically operated portable machines.

Aerosol canisters are designed to operate in conjunction with a dedicated kit. This kit comprises of thermal sleeves that wrap around pipework and valve connector attachments with refrigerant delivery tubes. These sleeves are usually made of durable nylon material.

Thermal sleeves come in a variety of sizes to fit the common pipe diameters in use today. The thermal sleeves act as a barrier to contain the evaporate and to delay thawing.

The refrigerant is a volatile gas that has been compressed to form a liquid and then held in that state under pressure in the canister. It is the sudden reduction of pressure that enables the liquid to return to its gaseous form. In doing do, it draws heat from its surroundings. This causes the freezing action.

For plumbing purposes, the thermal sleeves are applied to pipes and the liquid gas introduced where it evaporates to form an ice plug close to the working area, and if necessary, at a point beyond to prevent backflow. There should be a distance of at least 200 mm between the working area and the sleeve (s).

The process works best on horizontal pipework, but can be used on a vertical pipe.

There must be no flow of water through the pipes at the time of freezing, as this would inhibit the formation of an ice plug. Boilers and pumps must be turned off and leaks temporarily patched. The water in the pipes must also be cold, with the ambient room temperature below 20 degrees C for optimum efficiency.

One end of the flow pipe for the refrigerant is attached to the thermal sleeves, which in turn must be securely fastened to the plumbing pipework. The other end of the flow pipe is attached to a valve located on the canister. By operating the valve, the liquid under pressure in the canister passes down the tube into the thermal sleeve, where it expands and converts into a gas. This causes water in the plumbing pipe to freeze and form an obstructing plug of ice. The obstruction blocks the water flow. The refrigerant should be delivered in short bursts to prevent wastage or overspill. The thermal sleeves must remain in place until the plumbing work is completed. A naked flame and blowtorch cannot be used and plumbing fittings that are to be installed must be of compression or other non-heat requiring types.

Depending on the pipe-work material and diameter, and the ambient temperature of the water and room, the plug will form in copper pipes in around five minutes. Plastic pipes will take up to twenty minutes. An audible click from the device will inform the user that the plug has formed and that the plumbing work can commence. The ice plug will effectively prevent water flowing for about thirty minutes although it is possible to maintain the plug with further bursts of refrigerant.

It is important to ensure that there is sufficient aerosol refrigerant to complete and prolong the plumbing if it becomes necessary. The aerosol and gases produced must be used in a well-ventilated area. The refrigerant will cause serious burns if it comes into contact with skin or eyes and must not be inhaled.

Pipe freezing machines are an alternative to using a disposable canister. The principal of freezing the pipes is similar, however, the gas evaporation and re-pressurising is contained within the machine and is much safer to use. It is also environmentally friendly as no toxic gases are released into the atmosphere.

The machines are electrically operated and will supply and maintain a freezing process to pipes indefinitely, so long as the power supply is maintained.

The refrigerant is delivered via pipes to clamps attached to the pipework. The freezing process and maintenance are automatically controlled by the machine, which will also indicate when the ice plug has been formed. The clamps and the freezing process must remain in place until the work is completed.

There is a variety of machines on the market and manufacturers make machines that are capable of freezing any diameter of a pipe. The larger machines are regularly used by water companies to complete major pipe maintenance work.

Pipe freezing machines are expensive to purchase but can be hired on a daily basis from plant and tool hire companies. Currently, expect to pay around £50/day.

Both methods of freezing pipes for plumbing purposes are very effective if the manufacturer’s instructions are followed. Occasionally, where pipes are located in confined spaces, or very close to walls, neither conventional sleeves nor clamps can be effectively used. With pipe freezing machines there is a type of clamp that is held in place by rubber straps. The clamp freezes one side of the pipe and will take longer to form an ice plug. However, this can be used effectively where a normal clamp may not fit.

When cutting pipes to facilitate plumbing work, consider implications surrounding earth-bonding issues with electrical supplies.

For a one-off job, pipe freezing aerosols, and the kits that are available to facilitate their use may be the most practical option. Inclusive kits vary in price depending on size and the required application. A very simple kit can be purchased for around £30. Fittings and gas canisters can also be purchased individually. The kits and accessories are widely available from plumber’s suppliers and DIY outlets.



How to Repair the Main Stopcock

The house stopcock, or shut off valve, controls the mains flow of cold potable water into the property. It is commonly located under the kitchen sink although it may also be installed near a front door, in a cupboard, or even under a floorboard. It would be uncommon to find more than one stopcock controlling the mains water supply into an individual property.

Most stopcocks have to be manually operated, although there are now some being installed that are electronically operated. Electronically controlled stopcocks require specialist maintenance and should not be serviced by the householder.

It is most important that the householders are able to locate, identify and operate the manual stopcock. This is because it is the most practical way of closing off the pressurised mains water supply into the property. This would need to be carried out quickly in the event of a water leak or burst pipe within the property. It might also need to be operated to facilitate water appliance repairs or installations.

Perhaps the biggest problem that occurs with mains water supply stopcocks is the inability to turn them off. This is due to infrequent use. Without a frequent operation, the internal mechanism becomes affected by mineral particles and substances produced by the effects of metal corrosion. These adhere to the surfaces of the moving parts. Over time, this causes the washer and jumper mechanism to seize up. The crutch head becomes very difficult, if not impossible to turn. In the panic of a plumbing emergency, it is not uncommon for a householder to apply excessive force to the crutch head of a seized stopcock. Unfortunately, this can result in the crutch head shearing off from the spindle, leaving the valve in the open position.

It is also important to ensure that the operative knows which direction of turn opens and closes the stopcock. It is not unusual to find a householder has sheared off the crutch head by applying excessive force in the wrong direction.

Anti-clockwise opens. Clockwise closes.

To prevent problems occurring with a stopcock, it is a good idea to turn it on and off regularly. This will help to prevent a build up of material and ensure that the mechanism operates freely. It is also a good idea to turn a freely operating stopcock fully on, and then give it a half turn clockwise and leave it at that position. This will provide a little extra play on the device should it become stiff to operate in the future.

To free a seized or difficult to operate stopcock, spray a little penetrating and lubricating oil onto the spindle and gland nut, and then leave it to seep into the mechanism. This should solve the problem. If that does not work, slacken the gland nut and apply the spray again. If the stopcock still refuses to operate, a small amount of force can be applied to the crutch head using a wrench.

Occasionally, applying a carefully directed blowtorch flame to the gland nut will provide just enough metal expansion to free the seized mechanism. It is a wise precaution to clean away any surplus penetrating oil before doing so.

If all attempts to free a seized stopcock fail, the water supply can be turned off at the water supplier’s main valve. This will usually be located outside the homeowner’s boundary. It may be on the pavement under a small iron cover marked SVS, or it may have the water suppliers identifying mark. Sometimes this valve is a normal stopcock, but more often than not it is a spindle headed valve that requires a specific tool to operate it. This can be obtained from tool hire firms.

Alternatively, the water supplier will attend to operate the device. This mains stopcock is the property of the water supplier and its maintenance and operation are technically their responsibility.

On some networks, turning off the water supplier’s mains water valve will affect other residents. They should be forewarned about any interruption to their supplies.

Turning off the water supplier’s mains supply valve will facilitate the repair or replacement of the domestic water stopcock. It is quite feasible for a competent DIY enthusiast to strip down and service a mains stopcock or to remove and install a new one. However, the location of the stopcock may make access and work on it difficult due to restricted working space.

When removing and replacing a domestic mains stopcock, there will be a significant amount of water and pressure remaining in the system when the supplier’s valve has been turned off. This pressure can be released by turning on the domestic cold-water tap. Unless a drain valve has been installed close to the stopcock, a suitable receptacle will be required to collect any surplus water draining from the pipe above the stopcock.

On other occasions, a householder may become aware of a slow leak from a stopcock. Left unattended, a small leak can cause substantial damage to the fabric of a property. The most usual causes are leaking compression nuts or deterioration of the gland packing material.

Leaks from the compression nuts can be addressed by gently tightening the nuts. Care should be taken to not over-tighten compression nuts, as this will interfere with the correct operation of the stopcock. The stopcock should be held firmly with a set of grips whilst tightening the compression nuts to prevent fracturing the attached pipe-work.

Leaks from the gland head can be rectified by trying to tighten the gland nut. If that fails to stop the leak, removing the crutch and unscrewing the gland will allow the householder to clean away any detritus and old packing material. It is not necessary to turn off the water supplier’s main valve to accomplish this task. PTFE tape can then be gently wound around the exposed area of the spindle and prodded down into the gland area with a screwdriver. The gland nut and spindle can then be re-attached.

In general, the regular inspection and operation of the domestic mains stopcock will ensure problems do not occur, or only become apparent in an emergency.

Because of the substantial damage that can be caused by unmanageable releases of water under mains pressure and the subsequent insurance implications, if there is any doubt over issues relating to competency, professional assistance should be sought in relation to stopcock operating issues.

Problems with Dead Legs

I recently bought a new washing machine. Not that there is anything particularly out of the ordinary in doing so. The working life of a modern washing machine seems to be considerably shorter than that of the robust models of the past. Whether that is due to the increasing complexity of the electronics or the designed-in time-dependent failure of its components is a matter of opinion.

The main thing that did attract my attention was the fact that the new machine had just one water inlet hose. My previous washing machine had two independent water inlet hoses, one for hot and the other for cold water supply.

It seems that now one cold supply hose is the only water inlet connection required.

This naturally left a length of redundant hot water supply pipe. Although it was fitted with an inline valve to close of the hot water flow, I decided to fit a blanking cap to the hose connection end as a secondary precaution against leaks.

Unknown to me I had just created a dead leg.

That might have been the end of the story had I not read an article about the increasing awareness of the potential problems of microbial proliferation in domestic water supplies, particularly in dead legs.

A dead leg is a section of water pipe that branches from a T-junction and is blanked-off due to it no longer being required. It can also refer to a section of water pipe that services an appliance that is infrequently used.

Apparently, such lengths of pipework can become traps for silt and organic material. This provides the perfect environment for the development of microbial agents that can pose a danger to householders.

This is particularly the case in respect of dead legs on hot water systems.

Although hot water may be flowing through the domestic system at a temperature and flow rate that prevents microbial development, a dead leg remains as a sump for collecting debris.

The water temperature in the main domestic circulation is usually at a high enough temperature to inhibit microbial growth, but in a dead leg, the water stagnates at a lower temperature.

The dead leg on a hot water system may pool water at the optimum temperature to allow scale formation. The surface provided by developing scale, the presence of nutrients from collected sludge and the warmth from the water provide the ideal environment for the development of dangerous organisms.

Organisms such as Amoebae, Ciliates, Coliforms and Algae may proliferate and disperse into the main circulation. However, Legionella and Pseudomonas bacterium can also flourish.

So how do these organisms get into the hot water supply to begin with?

Mains cold water from the provider is chlorinated to destroy most potentially harmful organisms, but contamination can still occur due to leaking supply pipes or unprofessional plumbing work.

Perhaps the greatest source of contamination is a water storage tank, particularly one that is uncovered or that has an unscreened overflow pipe.

Although regular flushing of the hot water system, either intentionally as a maintenance task or by continual domestic usage, will help to prevent microbial contamination, dead legs will remain un-flushed and prone to scale formation. The scale provides a perfect material for organisms to adhere to.

Fragments of contaminated scale can break away from formations in dead legs and become suspended in the domestic water flow.

In the case of Legionella, the bacterium can survive the flowing hot water temperature and then incubate in lengths of T-pipes supplying hot water outlets when the temperature drops in-between outlet demand.

The bacterium can also thrive in showerheads in-between usage, particularly where scale buildup in the showerhead provides niches for development.

Although microbes in contaminated hot water can be harmful if ingested, bacterium like Legionella pneumophilia can be dangerous when inhaled.

The inspiration of aerosol particles can penetrate deep into the lungs.

Aerosols are minute water droplets suspended in the air. They are created by water falling onto a hard surface; such as occurs when running a tap, a bath, or having a shower. Flushing a toilet or spraying water will also produce aerosols.

Whirlpool and Jacuzzi type bath installations are now being identified as potential sources of microbial incubation and harmful aerosol formation, particularly where regular sanitation and cleaning maintenance is neglected.

Aerosol particles in the air can remain suspended and circulate on air currents for over twenty minutes.

Although Legionella infections are not passed from person to person, they do occur in clusters. The symptoms can vary from mild flu-like conditions to life-threatening pneumonia. People with compromised immune systems or pre-existent lung conditions are the most vulnerable to acquiring Legionella infection. The mortality rate can be high among confirmed cases in susceptible people.

However, it is thought that many mild cases go undiagnosed and that the incidence of Legionella infections amongst the population is much higher than the identified and confirmed cases suggest.

On the Continent, plumbing procedures encourage the installation of loop systems rather than T installations to help to prevent microbial development problems in domestic hot water supplies.

Best practice and Water Regulations now issue guidance on dead legs and associated blind ends. It is recommended that redundant T water pipes are removed and the T replaced with a standard in-line pipe connection.

It is also worth noting that landlords of rented properties must undertake a risk analysis of the potential for water-borne infectious agents to develop in services installed in properties they let. They must also take action to make safe any potential sources of microbial contamination. Failure to do so can expose the landlord to criminal action and substantial litigation issues should subsequent related harm occur to a tenant.

I have now removed my blind end and in conjunction with a regular flushing of my entire domestic hot water system, can rest assured I am doing as much as practical to reduce the chances of my household contracting a water-borne infection.




Replacing a Hot Water Cylinder on a Vented System

A friend of mine has just moved into a rather splendid period property. Large and spacious, it is ideal for his rapidly expanding family. With a modern condensing boiler and a programmable zoning installation controlling the radiators throughout the house, he is confident he can keep his heating bills under control.

The previous occupants also had a large family and found an open vented hot water storage system ideal for their requirements. Where large amounts of hot water are required on-tap, storing hot water in a cylinder is a practical solution to cope with a high quantity demand.

With the property having three floors there is also a good head of pressure available from the cold water feed tank in the loft. This provides a good hot water flow and pressure rate through the cylinder and out of the taps.

However, after taking off the hot water storage cylinder insulation jacket to inspect the tank, my friend noticed that water had been leaking from the indirect heating coil flow pipe leading into the cylinder. Green and white encrustation around the external connection was quite evident along with an indication that someone had tried to stop the leak with a filler compound in the past.

Realising that the copper cylinder was quite old, my friend decided it was time to replace it, rather than try to mend the leak.

Because he has an open vented hot water system, he decided to undertake the work himself. Open vented means that when hot water is heated and expands, the surplus water volume is directed up a pipe leading to the cold water feed tank. If the expansion becomes too great within the system, surplus hot water can be discharged back into the cold water feed tank. This maintains a low and safe working pressure within the system. Any excess of water flowing back into the cold water feed tank is simply expelled from the property via the overflow pipe.

If he had inherited an unvented system, the replacement of a hot water storage cylinder would have been a specialised procedure requiring expert installation.

The original hot water storage cylinder was snugly located in an enclosed cupboard in the bathroom. Although this meant that installing a new cylinder would have to be undertaken in a rather confined space, my friend decided that this location would still be suitable. The installation would simply require the removal of the old tank and the insertion of a new one, plumbing into existing fittings.

New hot water storage cylinders are available in a variety of sizes. Smaller properties can also benefit from installing vented combination cylinders, where the cold-water feed and expansion tank is incorporated into the storage unit. This is designed to save space but can lead to problems with low hot water flow rates.

General domestic vented hot water storage cylinders come in a variety of sizes ranging from 74 litres up to 450 litres. Because the existing cylinder in my friend’s house had a 200-litre capacity, he decided to replace it, like for like, with one of the same capacity and dimensions to ensure that it would fit into the available space.

The new cylinder was coated with a highly efficient foam insulation skin and also had provision for the attachment of a backup electric immersion element in the same position as the existing cylinder. Inlet and outlet fitting locations were also chosen to be identical to try to ensure a problem free installation.

Having obtained the replacement hot water storage cylinder, my friend turned his attention to removing the old one.

Firstly, he shut down the boiler and all the other accessories, pumps, electronic diverter valves and programming installations and then, because there were no additional isolating valves, drained down the central heating system.

He then isolated the current immersion heater element electrical supply.

The existing cylinder now needed draining. This was accomplished by turning off the mains cold feed to the water feed and expansion tank and locating the drain tap, fortunately, plumbed from the rear of the storage cylinder and feeding through to the front.

Next, he disconnected the electrical contacts in the head of the electric immersion heater and then removed the external thermostat device that was secured to the wall of the cylinder.

He was then able to unscrew the cylinder attachment fittings. They were the heating coil inlet and outlet points and the hot water outlet pipe at the top of the cylinder. He was fortunate that they were easy to free and unscrew. However, he could have cut the pipes at appropriate points, ensuring that he could re-plumb when necessary. He also took the precaution of marking the pipe-work to identify which pipe corresponded to which function.

To ensure convenient re-plumbing of the cold-water inlet, in this case, located at the back of the cylinder, he cut this pipe some way above the cylinder. By doing this, he could attach fittings and a length of copper pipe to the rear of the new cylinder prior to moving it into position. This saved him having to struggle to plumb the cold feed into the base of the back of the cylinder when placed in its new location.

He enlisted my assistance to remove the old tank and carry it downstairs. We were quite surprised by the weight of the old cylinder and decided to cut the top off and examine the internal area. This was encrusted with limescale, with a thick coating covering the coils and electric heating element. The base of the cylinder had about six inches of scale and debris, almost clogging the cold water feed inlet. This indicated that the water supplying my friend’s property was particularly hard.

Attention now turned to the new replacement cylinder. To ensure a watertight fitting of a new immersion heater element, a small circular ring of foam insulation was cut from the edge of the element fitting area. The element was then screwed into position, seating perfectly into the cut area and forming a tight seal.

With fittings, and an appropriately measured length of copper pipe attached to the rear cold water inlet point, not forgetting the attachment of a new drain valve leading from the back base coupling to the front area, the new cylinder was inserted into position.

The heating coil inlet and outlet pipes and the hot water outlet pipes were re-attached. The cold-water inlet pipe extension from the back of the cylinder required coupling to the pipe from the cold-water feed and expansion tank.

To facilitate future maintenance work, gate valves were installed at suitable pipe junctions to enable the cylinder to be easily isolated from all water supplies.

The new immersion element was rewired into the mains, and a small piece of insulation foam was cut from the front of the new cylinder to allow attachment of the thermostat.

The mains water was turned back on and the entire system was refilled, not forgetting the addition of inhibitor into the central heating system. The boiler was then re-started and all contributing electrical appliances turned on.

The immersion heater was checked to ensure it was working, radiators were bled to remove airlocks and the system restored to a functioning hot water and central heating installation.

The new hot water storage cylinder and its related plumbing couplings were frequently inspected for a few weeks to ensure that no problems or leaks emerged.

With the new hot water storage cylinder installed, my friend could now relax, confident that a major cylinder failure and water leak issue was unlikely to arise.