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.

Identifying and Fixing a Damaged Heating Pipe

There is no doubt about. You have a boiler losing pressure and you have no idea why. You’ve checked the central heating radiators and pipes for any visual signs of leaks and found nothing.

You’ve also called out the boiler engineers and they have checked the boiler over for faults and replaced a suspect part. The expansion vessel is working normally and there is no overflow from the pressure release valve.

Yet still, over a period of a few days the boiler operating pressure starts falling and you have to keep topping the system up.

The real worry is that there is a leaking pipe under the floorboards, or worse still, buried within the new hydronic under-floor heating system you’ve just had installed under the ground floor.

This is going to take a little bit of detective work to find just where that leak is hiding.

That is of course if it is a leak.

Just because boiler engineers are Gas Safe registered it does not mean they are all seasoned and highly experienced. Unfortunately, there is a minority who are inclined to diagnose the most likely fault, replace a part and hope for the best. When they are called back, they simply move on to the next likely fault and eventually fix the boiler by the expensive process of gradual elimination.

So, back to our devil of a problem. To see whether the boiler is at fault, the following technique may help.

The boiler should be isolated from the system by turning off the flow and return valves to heating networks and the mains inlet source. The boiler must have at least one bar of internal pressure registering on the pressure gauge.

The boiler should be left unused for at least 12 hours. If the pressure drops within that time, then the fault very likely lies with the boiler. If the pressure is maintained, the fault probably lies somewhere within the heating circulatory system.

Of course, whilst the test is in operation there will be no domestic hot water available, particularly if you have a combi type boiler. If you are fortunate to have a hot water storage cylinder with an alternative electrical element heating source, you will not be affected by this temporary domestic hot water problem.

If the boiler appears to be at fault, get the boiler engineers back and insist that they rectify the fault.

If the heating circulatory system appears to be the problem, you should have a dedicated heating network that feeds the under-floor heating system separately from the radiator network. The manifold which connects the hot water to the under-floor heating pipes should have isolation valves fitted. On this manifold, it is often usually possible to turn off the under-floor heating or the radiator network separately so that each can run either together or independently depending on the household requirements.

With the boiler operating at normal pressure, isolate each network flow and return valves independently for at least 12 hours and monitor the boiler pressure. A drop in pressure on either network will indicate which has the leak. A drop in pressure on both networks means that you either have leaks in both networks or that there is a leak in the pipework from the boiler to the manifold. To identify whether the latter is the case, turn off all heating network flow and return valves with the boiler operating at normal pressure for 12 hours. If the pressure drops then the leak lies on that circuit.

If there are no pressure drops within the circulatory system, call the boiler engineers back, again.

When diagnostics suggest that the under-floor heating network has a leak, depending on the warranty you have, contact the installers. If you installed it yourself or it is out of warranty, check your household insurance for cover.

It is possible to get a general idea of where the under-floor heating leak is located by using thermal imaging equipment. If it can be located, the area can be dug up and the leak found and repaired or bypassed with a new loop of pipe.

Dealing with leaks in under-floor heating can be expensive to address. The wrong diagnosis can lead to the entire floor being dug up and no leak being found. When initially laying under-floor heating it is wise to protect any pipes from the corrosive action of concrete.

If all indications lead you to suspect that the leak lies somewhere within the central heating network, it is important to thoroughly inspect all accessible parts of the pipe-work and attached appliances for any visual signs of leakage. On hot pipes, water from minor leaks will very quickly evaporate.

Where forethought has provided isolation valves at important junctions, these can be used to isolate sections in the elimination process previously described.

Narrowing down the area of the leak will allow for close scrutiny of a small section of visible pipes and fittings. Occasionally the most unlikely source of a leak may be the culprit, such as a loose compression fitting or a faulty radiator check valve. Appliance fittings such as those attaching pumps and motorised valves must also be checked.

Once narrowed down and without any visual signs of a leak, attention must be drawn to pipe-work hidden below floorboards etc.

Lifting floorboards in a limited area may give an instant visual indication of a leaking pipe. Possible compression fitting failings or badly soldered joints will show up as a damp patch on the surface beneath the fittings. Sometimes a nail hammered into floorboards and puncturing a pipe is the culprit.

Before attempting to repair a leaking pipe, always turn off the boiler and mains water. If the heating flow section cannot be isolated, the system will have to be drained.

Repair is usually straightforward and limited to either re-tightening or replacing compression joints, or removing the affected section of copper or plastic pipework. A new piece of pipe is then inserted and secured with appropriate fittings. The use of in-system circulating leak repair fluids is not recommended. They can cause other damage to the system and often invalidate warranties.

Once the pipe-work is repaired, the system can be re-filled. Do not forget to include inhibitor. Radiators may need bleeding.

Hopefully, the problem will be solved. However in some rare cases, leaks are never found, or one is discovered and fixed, only for more to appear. The householder continues to suffer from system pressure issues that indicate leaking pipes and has to continue the unresolved chore of frequently topping up the system. In cases like these, it is likely that there are numerous minor failings, particularly in old systems. In these situations, a complete central heating replacement is probably long overdue.


Fitting a Magnetic Filter? DIY!

If at any time you thought that your wet central heating system was a ‘fit and forget’ feature, I am sure that now, and possibly as a result of experience, you’ll have come to a completely different opinion.

Perhaps you might have thought that you could save money by running your central heating for a a few years without regular maintenance.

Trouble is, sooner or later your system is going to start deteriorating and could eventually succumb to a rather expensive failure.

Something of a false economy.

In addition, a lack of regular attention will cost you more than inconvenience and costly breakdowns.

Running a poorly maintained system can send your heating bills sky high as the pump and boiler struggle to heat and push water through constricted, scaled pipes, sludge and sediment clogged radiators and mineral-encrusted heat exchangers.

Regardless of the type of system you’ve had installed, whether it is a sealed combi, open or a vented heating system, the most common problem you are likely to experience is that of natural corrosion of the metallic components of the system.

This can be reduced very effectively by periodically power flushing the system and by the regular use, and maintaining of, an adequate concentration of inhibitor.

However, power flushing can leave behind stubborn sediments that could eventually dislodge and become suspended in the circulating water. These particles, usually composed of metal oxides, can continue to cause damage to boiler components even in what might have been considered a cleaned system.

This, combined with a continual accumulation of debris, can increase the frequency of the need to power flush.

The answer to removing these particles lies in the introduction of a magnet into the system.

There are a number of domestic magnetic filters available, but the most popular and effective is the Magna Clean device.

The Magna Clean is a compact filter appliance of simple but ingenious construction containing a powerful internal magnet. This very effectively collects any metallic particles suspended in the water. Its small size means that it can be fitted unobtrusively in confined spaces.

Many central heating maintenance companies recommend the fitting of a Magna Clean device, particularly after power flushing or the installation of a new boiler.

And they will also quote you a considerable sum to do so, along with a repeat fee for annual cleaning and maintenance!

However, a Magna Clean is self-powered, has no moving parts and is simple to install.

A Magna Clean can be purchased from most D.I.Y. outlets and comes in a number of designs that will fit into most central heating installations.

You can expect to pay between one hundred and one hundred and fifty pounds for the appliance including VAT.

Although the best time to install a Magna Clean is following a power flush, it is not a precondition.

The main advantage of installing a Magna Clean following a system flush is that the boiler or heating device has already been turned off and the system has been drained.

When the system is drained, the Magna Clean should be installed between the last radiator on the system and the system boiler. Generally, the device is fitted on the return hot water pipe just below the boiler.

The device should always be plumbed into the pipework in accordance with the manufacturer’s instructions. This is not a complicated procedure and can be accomplished in minutes.

The Magna Clean Pro 2 is perhaps the simplest device to fit and requires a 150 mm section of pipe to be cut out of the return hot water circuit. The device can then be securely connected into this gap with a spanner. The inlet and outlet valves are self-contained and the device can be removed and replaced anytime quite easily.

The Magna Clean Pro 2 also has an addition trap at the base of the device to collect non magnetic particles.

It is recommended that the Magna Clean magnet should be cleaned once a year, but it is probably wise to clean it more frequently, particularly on an older system where previous inhibitor and flushing practices may have been neglected.

To clean the magnet, close the inlet and outlet valves on the device. Release any pressure in the unit by turning the bleed valve at the top, and then unscrew the device top with the dedicated tool which is provided when the device is purchased. Then remove the magnet in its accompanying plastic sleeve.

The surface of the plastic sleeve will very likely be coated in black ferrous sludge, even after a short period of operation. It is the monitoring of this sludge that will give an indication of the level of contamination within the system and the frequency with which the filter should be cleaned.

To clean the magnetic filter simply run it under running water to wash away the sludge particles. The filter can then be inserted back into the device, the top replaced and the valves opened. The bleed valve on top should be operated to remove any trapped air.

Job done.

Beware of heating companies who, after installing a new boiler, suggest the installation of a Magna Clean device as an alternative to power flushing. Operating a new boiler without power flushing can invalidate the boiler warranty.

The Magna Clean installation should be seen as complementary to good central heating maintenance and not as an alternative.

It is estimated that the use of a Magna Clean device can knock up to sixty pounds of annual heating bills.

That has to be a saving worth considering.

Pressure Booster Pumps

Low water pressure, as an infrequent event caused by your water supplier carrying out maintenance on its mains network, or as the result of a burst mains at a distant location, it is something that cannot be avoided.

However, when it occurs frequently, often at certain times of the day, or when it is a constant problem, it can be a major issue. Showers and boilers, which require a minimum pressure to operate for safety reasons, will often not work.

Constant or inconvenient low water pressure can have numerous causes. It is a good idea to try to establish the cause before going to the expense of purchasing and installing equipment to boost domestic water pressure. Adding extra pressure to a damaged or partially blocked domestic water network may cause damage to the pump and plumbing.

Is the low water pressure limited to the domestic hot water supply or a problem concerning the entire water supply?

Where domestic hot water is supplied by a cold tank gravity fed system, a suitable head of pressure needs to be present to force water through the system. If the cold water storage tank is not at a suitable height, for example in a single storey house, the pressure may be low or at an unacceptable level.

If this is the case, a suitable water pump fitted into the hot water supply line at the exit point from the hot water cylinder will pump water on demand and at a suitable pressure to outlets.

It is important to ensure that the cold water header tank has an adequate capacity to feed the hot water storage cylinder when the pump operates and starts to empty it. Insufficient capacity may allow air to be drawn into the system.

For combi and sealed boiler systems and for general mains cold water, it is important to ensure that a low water pressure problem is not being caused by a leak. This could occur either within the boundary of your own property or that of any other property that is supplied by the service pipe.

It is also a good idea to check that your mains stop cock is turned fully on. It is not unusual to find pressure and flow problems caused by a stiff valve that a previous user failed to open fully.

The water company that serves your community will be able to determine whether low water pressure is the result of a leak or simply due to local demand on their side of the supply line.

Water supply companies sometimes minimise pressure within a local network to avoid causing damage to their already deteriorating systems.

Where a water company reports that water pressure and flow rates are within expected tolerances within its own mains network up to your boundary, the next step is to ensure that the problem is not being caused by other issues in the domestic network.

Over time, domestic pipe-work can become clogged up with encrustations of sediments and deposits that may be impossible to clear. If this is the case, re-piping is the only solution.

Occasionally, where lead and exposed copper piping remains in older buildings, the pipe-work can become accidentally crushed, restricting the flow around the property.

Sometimes following an investigation be the water supplier, it can be established that a low water pressure issue is not one that can be remedied by them. Perhaps your property is situated on a hill or low pressure is just an accepted inconvenience in your particular area,

If this is the case then a domestic pressure booster water pump could be considered as an option for increasing your water pressure.

There are a considerable number of manufacturers of pressure booster pumps and many different designs.

You should carefully establish that any pump you purchase is capable of supplying the required pressure. It is also important to consider where the pump will be located. It will need to be installed on the mains cold water pipe-work close to the stopcock but before any appliance.

When installing, it will require an appropriate electrical supply and an isolating valve on the pumped water flow line to enable future servicing.

Many booster pumps incorporate into their housing or require a pressure and expansion device. These devices prevent damage to the pipework system or attached appliances in the event of an excess pressure problem.

Bearing these points in mind, the size of the pump is going to be an important consideration to ensure that it, and its necessary fittings, will fit into the desired area.

Pressure booster pumps are designed to maintain a minimum pressure within the system and to operate automatically when they detect a drop in pressure caused by a demand. They then continue operating until the demand discontinues and a cutoff pressure is reached.

Most pumps operate quietly. When installing the pump consideration should be given to the surface upon which the pump is secured to minimise amplification of noise caused by vibration.

The actual plumbing of a pressure booster pump is an easy task. It is simply a matter of making an appropriate cut into the existing mains water pipework and attaching the pump inlet and outlet connections. If extra connections are required to accommodate expansion and pressure release mechanisms these are usually straightforward procedures.

If you are considering undertaking the work yourself, then pumps are readily available and installation instructions are usually quite comprehensive and easy to follow.

As with all DIY tasks, care should be taken to ensure that any work undertaken is within the capabilities of the person undertaking it. Poor workmanship can be expensive to correct. It is also wise to consider household insurance issues that may arise due to water damage caused by non-professionally installed appliances and subsequent plumbing failures.





DIY Copper Plumbing and Fittings

When it comes to carrying out maintenance tasks or simple repair work within the home, nothing can give as much satisfaction as DIY. The pleasure that comes from identifying and successfully completing the required work adds a certain feeling of being in control of, rather than being controlled by the technology and installations within the home.

It is also fair to acknowledge that being able to do all or part of the work that would normally require the intervention of a plumbing or heating engineer is likely to save a considerable sum of money. However, the ambitious DIY enthusiast should apply some caution to ensure that any work undertaken is within the scope of the enthusiasts’ skills and capabilities. Where DIY goes wrong, the cost of putting the situation right can be costly.

Although there are many materials available to the DIY heating and plumbing enthusiast, copper perhaps is the most widely used and most durable material.

All alternative pipe-work materials have their place and many offer an ideal substitute for copper for those who would prefer not to learn the basics of working with that material.

Yet learning how to install copper pipes and fittings can be a joy in itself and although skills are not learned overnight, the basics can be understood very easily. Getting the practice that would ensure any work carried out was as good as that of a professional would be another matter, but the same could be said when using alternative materials.

Copper is a proven, durable and reliable material, which is still the choice of artisan tradesmen, and when installed correctly makes the extra time it takes to install it aesthetically and visually worthwhile. It might be expensive to purchase when compared with some plastic alternatives, but copper and its brass fittings retain a scrap value and are completely recyclable.

Copper pipe comes in a three basic types. Thin, medium and thick-walled. Medium walled is a general type for domestic use. It can be purchased in rolls or in specific lengths. There is a flexible type of copper, suitable for repair work, and a rigid type of copper for general installations. Copper comes in a variety of diameters from 1/4 inch to 2 inches.

There are three categories of pipe fittings. The first category includes fittings designed for making bends and turns in the pipe. The second category has fittings made for joining or branching copper pipe. The third category is comprised of couplings, slip couplings, cast iron and other pipe-work adapters. All of these fittings can be used with either rigid or flexible pipe.

Copper pipe can be cut to the required lengths with either a dedicated pipe cutter or a hacksaw. It is important to ensure that the cut is vertical to the horizontal pipe to ensure a tight connection into the coupling. Once cut, the cut surface must be thoroughly cleaned externally with an abrasive material such as steel wool. The internal cut area must be reamed with a knife or suitable implement to remove any burs which, if not removed, can interfere with the smooth flow of water through the pipe causing erosion and corrosion.

Any coupling that is to be used must also be cleaned to remove debris that could affect the integrity of the join.

Copper pipe can be joined together in a number of ways. Brass compression fittings can be used to secure pipe joints. These rely on the deformation of an olive placed on the pipe. Pipe threads are wound with PTFE tape prior to compression. Applying a tightening procedure to the nut on the compression fitting compresses the olive into the joint with the copper pipe and brass fitting producing a watertight seal.

Adhesives are also available for joining copper pipes and fittings. These are designed to withstand water temperatures up to 300 degrees F. an adhesive might be suitable for use in some installations and repairs but would generally be regarded as unsuitable for extensive work.

Soldering and brazing are perhaps the most widely used methods of joining copper pipes. Soldering is suitable for general purpose. Brazing requires greater heat and metal fillers to replace the traditional solder. Brazing is best suited to systems that are likely to operate with a high working pressure.

Copper fittings can be purchased that are already primed with solder and simply require the joints to be cleaned. Flux should be applied to the externally cleaned pipe work and the internally cleaned core of the fitting prior to soldering. Flux is a compound that prevents oxidation of the copper pipe when it is being heated for the soldering process. Care should be taken with flux to avoid skin and eye contact or accidental ingestion.

Joints must also be completely dry to ensure a secure and reliable joint.

Prior to soldering or brazing, the pipework must be suitably secured to prevent any movement or vibration that might affect the integrity of the joint. Any vibration or movement will prevent the solder from setting properly and will result in a joint that is likely to fail.

For general soldering, the successful joining procedure is achieved through solder being drawn into the narrow space between the pipe and the coupling. This is achieved through capillary attraction. The pipe and joint area are heated to a point that will allow the solder to melt and run freely into and around the joint. Excess solder can cause problems if it enters the pipe-work interior.

Gauging the amount of heat required and the amount of solder to apply comes with experience gained through trial and error, however when heating the pipe with the blue part of the torch flame, a slight change in the flame colour from blue to green will indicate that the joint has reached a temperature suitable for the application of the solder. The solder should be applied carefully until it can be seen that the solder is starting to fill the joint cavity.

Care must be taken when using blowlamps to minimise the risk of fire or injury from burns. Soldered and brazed joints should be allowed to cool naturally prior to close inspection to establish whether the joint is secure. Where solder or metal filler has not completely filled the space in the coupling, the area can be fluxed again and reheated and a touch of solder or metal filler applied to remedy the situation.

It is possible to bend copper pipe to accommodate physical features in the building’s construction. This is often quicker than cutting, joining and soldering. The pipes can be bent using a specialised pipe bending apparatus. These are quite expensive to purchase and for DIY, a much cheaper alternative is a pipe bending spring. This is a length of spring coil, which is inserted into the pipe. With the spring in place, the pipe should be gradually bent to the required shape. If the pipe is bent with a sharp force, there is a risk that the bend will be formed with a rippled profile. This should be avoided.

Copper pipe cannot be successfully bent without one of these instruments.

Working with copper can be a satisfying procedure and is one that can be learned quite easily. As in all matters, practice with hands-on experience is the best way to learn.

Defective Motorised Valves

If you have a conventional wet heating system and boiler, the chances are that you will have at least one motorised valve incorporated into your system.

A motorised valve is a type of flow director, which operates to direct the flow of hot water from the boiler to either the domestic hot water cylinder circuit or the central heating circuit. Some types of diverter valves can direct the hot water flow to both circuits simultaneously.

A domestic hot water storage cylinder, heated by an internal coil and carrying hot water from the boiler is referred to as an indirect system. This system will usually comprise of a programmable time switch, room and cylinder thermostats and normally one or more motorised valves to control the central heating and domestic hot water supply.

These valves are usually operated by small electric motors and are activated by thermostats or the programmable control system. They can save fuel and money by ensuring that water is only heated by the boiler when it is needed and that the heated water then only goes to the part of the system where it is required.

Motorised valves are expected to operate for long periods and are subjected to considerable stresses caused by temperature fluctuations and contaminants like sludge, grit, scale and the other pollutants often found in the heating circulatory fluids. It is not surprising that faults and defects can arise with the components of motorised diverter valves.

Because of the interaction between various regulatory devices incorporated into a boiler and heating system, a fault with one component can prevent the whole system from operating. Where a motorised diverter valve is unable to communicate with the boiler, the boiler will not operate. This situation can occur when the system has not operated for a considerable time or where the supply of hot water from the boiler to the diverter valve has been turned off or obstructed.

Other indicators of a fault with a motorised diverter valve are either hot water in the domestic hot water supply but not in the central heating system, or vice-versa, or a supply of heating to both circuits when a demand for the supply is not required.

Although motorised diverter valves are manufactured by a number of companies and design of the valves varies, two common types are found in a domestic setting. These are two-port and three-port valves.
Numerous two-port valves can be used for zoning configurations.

The installation of either a two or three-port motorised valve depends on the pipe-work layout and the system requirements. Two-port motorised valves are used for the control of either a heating or a hot water circuit. Three-port motorised valves can provide separate heating and hot water circuits. There are two types of three-port motorised valves. One will only divert the flow of water to individual circuits whilst the other provides a mid position, delivering a shared flow to both heating and hot water.

Where a fault with a motorised diverter valve is suspected, there are a number of easy checks that can be made, and where a component part of the diverter valve is found to be defective in many cases it is relatively easy to purchase the component and replace it.

A motorised diverter valve is usually positioned near to the domestic water supply hot water cylinder. A first check should be to ensure that the motor is receiving the electric power it requires to operate. It is not unusual for the supply fuse or circuit breaker to be the cause of the fault.

On most motorised diverter valve units, there is a small lever on the motor housing. This lever can be manually operated to override the motor. It can also be used to establish where a fault might originate from within the unit.

With the system and unit power turned off; gently push the manual lever across its path. A certain amount of resistance should be felt. This is caused by the motor being manually turned. The lever should slowly return to its resting position once manual pressure is removed. If the lever moves with no resistance, or will not return to its resting position and is floppy it is likely that the internal mechanics are jammed.

To check if the valve is opening correctly, the system should be powered up and electricity restored to the pump. In this state, when the manual lever is pushed over, it will operate the valve and the lever becomes floppy indicating that the valve has opened. By touching the pipe-work below the unit housing it is possible to feel the heat from whichever circuit is operating. If one pipe is hot and the other cold the valve is closed. Pushing the manual lever completely over will open the valve and both pipes should become hot.

To check the internal components of the unit, first ensure that the unit is isolated from the electrical supply.

Next, unscrew the unit housing cover and remove it. This will expose the synchron motor. The motor sits on top of, and operates, the gearing mechanism situated directly below it. The gearing mechanism operates a spindle that either raises or lowers a ball to open and close the valve or in some models, rotates a shoe to direct water from one pipe to another.

The motor should be circuit tested to establish whether a current can pass through to operate it. If the circuit is not complete, then the motor will need replacing.

The old motor is easy to remove, however, the wire connections will need to be cut and then rejoined with connectors when installing the new synchron motor.

New synchron motors are easily obtainable and relatively cheap to purchase. It is important to ensure that the correct motor for the unit model is purchased. The motor must be rewired into the system in an identical manner to the one it replaces.

Occasionally the fault may lie with the micro switches that operate sensors informing the boiler of the unit’s valve position. These can be checked for voltage continuity across the system to discover if the fault is related to the switches.

Finally, a fault may lie with the gearing and spindle. If the connecting plate that attaches the motor and gearing housing to the pump valve mechanism has two securing screws, the housing section can be removed. If the connecting plate has four screws and the valve cannot be isolated by gate valves, the system will have to be drained before the connecting plate and housing section can be removed.

Removing the head unit will expose the spindle, which operates the valve. This can be turned with a small spanner or grips. It will not turn far. Occasionally the spindle will be slightly seized. This can be remedied by giving the spindle a sharp jerk with a spanner to free it. If the spindle is completely seized, the valve will need removing and replacing. If gate valves have been installed the valve can be isolated. If not, the system will have to be drained.

If the spindle is free and the gearing or micro switches in the unit head are at fault, a new complete head unit can be purchased and easily installed.

Where the identification of a fault with a motorised gate valve cannot be established, or where the necessary skills are not available for the user to undertake the repairs, the assistance of a qualified plumbing engineer should be sought.

Micro CHP Boilers

So. You’ve just upgraded your old central heating boiler to a brand new, highly efficient condensing combi boiler and you’re feeling pretty good about it. It came with an excellent warranty and service package and you’ve been advised that the central heating, the remote access control system and the sophisticated programming features are all examples of the latest technology.

Then your neighbour gleefully informs you that he is planning to install a micro CHP system. This naturally deflates your buoyant demeanour and sends you scurrying to the internet to see what advantages your neighbour might be obtaining.

Combined heat and power (CHP) boilers have been around since the 1970s. Due to their size, weight, cost and operating noise, they have generally only been suitable for industrial and large communal facilities. They have been installed to primarily generate electricity, usually by internal combustion engines and dynamos, with the secondary heat by-product being utilised for central heating purposes.

In recent years, technological advances, spurred on by rising energy costs, have enabled the concepts of the commercial CHP boilers to be adapted for domestic operation. These new compact and vastly superior devices are referred to as micro CHP boilers.

Although much of the technology is still in the developmental field, some micro CHP boilers are available on the market.

Current models are similar in size to a large domestic condensing boiler and are wall mounted. They are also plumbed into the central heating system in much the same way. They do require installation by a Gas Safe engineer and a Micro-generation Certification Scheme (MCS) approved installer. What makes domestic micro CHP boilers special is that in producing heat for domestic hot water and central heating, they also use the heat to generate electricity for the home. Any surplus electricity is then directed back into the grid. The boiler owner receives a payment for the electricity produced for domestic use and also a payment for surplus electricity fed back into the grid.

At first sight, it can all appear very attractive, and no doubt, the neighbour has seen this as an opportunity too good to miss.

There can be no doubt that electricity produced from a remote power station is a dirty, inefficient fuel. Only about 30% of the energy from the source fuel is actually available to the consumer. The rest is lost in production and supply.

Being able to produce electricity at the point of usage has great advantages and can provide energy efficiency levels in excess of 90%.

The vast majority of micro CHP models currently available employ the actions of a Stirling engine to generate electricity. Stirling engines are classed as external combustion engines. They utilise the properties of internal chambers filled with a gas, usually helium. This gas is responsive to areas of hot and cold within the chambers. Applying heat to the gas causes alternating pressures as it moves to a colder area, and vice-versa. This movement operates a displacer and piston. The piston moves up and down inside a copper coil at around fifty times a second to produce electricity, which is fed into the domestic electrical supply.

The Stirling engine generates about 1 kW of electricity as it operates.

Because these boilers use gas in a very controlled and efficient manner, the general idea is that the Stirling engine should operate continuously using small amounts of gas to efficiently generate electricity, and supplement the domestic central heating and hot water supply, with a boost heating facility to raise the hot water system to demand levels.

Every electrical kW produced and used by domestic consumption receives a payment from the energy supplier. This acts as an inducement to produce electricity and as a payment for not using the supplier’s inefficient electricity source. On top of that, any surplus electricity is directed back into the grid and receives a FIT payment (the Feed In Tariff) from the provider for each kW produced. The micro CHP boiler must be installed correctly by an MCS installer to qualify.

So where are the pitfalls?

The major drawback is the cost. Currently, purchase and installation costs are in excess of £5000. The life expectancy of models on the market is around ten years. With gas and electricity fuel prices so volatile, it becomes difficult trying to assess whether, or when, the capital expenditure and the interest payments on any financial assistance packages would justify installation.

There have been calls for a substantial increase in the FIT to make installation of micro CHP boilers more attractive, but as yet, there has been no movement on that proposal. As such, any financial advantages are likely to be very modest over the long term.

Perhaps the main obstacle for installing current micro CHP boilers is the situation in a potential buyer’s home.

Householders have responded favourably to Government incentives and environmental concerns over recent years. They have improved insulation and many have installed a variety of heat saving devices. Some have adopted technologies that supplement heat requirements with heat recovered through accumulators.

The amount of gas that is required to heat a well-adapted home is now significantly less than in previous times.

However, demand for electricity is increasing. Households now require constant electricity, not constant heat.

The 1 kW electrical output of a micro CHP boiler with the current FIT and kW subsidy does not make the installation of the boiler a realistic proposal at the moment.

The future for micro CHP boilers is, though, looking good. Manufacturers are developing superior alternatives to Stirling engines. Ceres are developing fuel cell technologies that will revolutionise domestic heat and electrical production. Within these fuel cells, heat and electricity can be generated without combustion removing all the problems associated with it.

Hydrogen cells are being developed to utilise the energy produced by micro CHP boilers and other green energy generating technologies. Hydrogen can be produced by surplus electrical activity and then used to generate electricity again at peak demand.

These green and clean modifications incorporated into, or complimenting micro CHP systems will make installation more of an attractive proposition in the future. The electrical kW output produced is much greater. Already the major energy companies are voicing disquiet about the possibility and implications of millions of micro energy producers feeding surplus energy back into the grid. And with some justification!

Perhaps lots of micro energy producers supplying a local network might be the answer to the ailing, aging and costly grid network, in addition to the public’s growing disquiet about the energy company’s extortionate energy generating profits.

In the meantime, compliment your neighbour for considering becoming a torchbearer and protagonist of nascent technologies.