Under-floor Heating

Technology throws up many interesting solutions to improve energy efficiency and comfort levels within our homes, and although the utilisation of an under-floor heating system has its origins in antiquity, the modern versions are far more ethical and efficient.

Roman hypocaust systems may have provided luxurious environments for villa owners, but the high levels of smoke emitted and the moral implications of forcing slaves to operate them might make them a particularly controversial hot potato today.

There are two modern and vastly improved systems currently available for domestic use. One is an electrical installation; the other is a wet system.

Although the two may appear to be in competition with each other for the homeowner’s attention, in reality each can provide an ideal and unique solution to an individual property’s requirement.

It is, of course, important to consider whether either system will be suitable in the first place and that requires a basic understanding of how under-floor heating operates.

Under-floor heating systems are generally only suitable for ground floor installation.

In a wet system, hot water from the boiler is pumped around a network of narrow pipes that have been laid onto a base directly under the floor.

An electric system relies on a framework of heat emitting wires that are laid under the floor in a similar fashion to a wet system. There is also an alternative electrical system that can be laid on the floor surface with a thin covering placed over it.

In contrast to radiators and other heat emitters that heat a small surrounding area and rely on convection to distribute the heat, under-floor heating provides a cooler radiant heat over a larger area. This heats the space consistently over the floor’s entire surface, rising upwards to warm the room very effectively.

With a wet system, where the surface area of a radiator requires the boiler to heat water to around 80°C to produce an effective radiant heat, an under-floor system will only require a 45°C – 60°C boiler setting to provide a comfortable floor surface temperature of around 27°C. The savings in gas or electricity are evident.

Now this is fine, but because of this lower operating temperature, the insulation qualities of the property become more of an issue. Where insulation and other heat conserving measures are below standard, the effectiveness of the under-floor heating can be reduced to such a level that the benefits of installation can never be utilised.

The best way to avoid this predicament is to commission a specialist to undertake a heat loss calculation on the property and establish whether under-floor heating can deliver the expected or claimed efficiencies. Where the advantages are confirmed, then the design and installation of a dedicated system tailored to the specific requirements of the property should be considered.

Most of the above issues are overcome in new-build situations, and if gas is available, then a gas fuelled, wet under-floor heating system is probably the system of choice. The installation of the system into the floor as an incorporation of the build progression simplifies the procedures and makes for a durable and effective heating system. Coupled with this, new-builds provide the opportunity for well thought out design concepts that can include ground source heat pumps and solar heating devices to compliment the under-floor system and reduce operating costs further.

In these situations, under-floor heating can be installed as individual zone areas within the property, controlled by a central manifold with diverter valves operated by individual thermostats.

Once installed, wet system pipe-work is maintenance free and guaranteed for up to fifty years by some companies. However, precautions should be taken to avoid damage by frost should the property be empty for a considerable period, and care must be taken before drilling into a floor where an under-floor heating system is installed.

Where, because of location, a supply of natural gas is unavailable, LPG can be considered as an alternative.

The greatest problems with under-floor heating occur in retrofit situations.

Although gas fired wet systems might be the preferred option, the practicalities of installation are such that the use of electrical systems are the only feasible option. However even this can be problematic. Under floor heating requires insulation below the system to prevent the heat being absorbed by the ground or any conductive substance it comes into contact with.

The recommendations for installation on a concrete base are a minimum of 50 mm of foil backed insulation material, for example expanded polystyrene foam, Kingspan or Celotex. The heating coils, either wet or electrical are laid upon this, usually in a serpentine or snail configuration. Sometimes the system has a dedicated layer that fits on top and incorporates the minimum insulation layer. This is then covered with a sand and cement screed to a depth of 65 mm to 100 mm, or a liquid screed of 50 mm.

This requirement can often be quite impractical in a retrofit situation. The elevation of the floor required to install the system may be undesirable and the cost of digging up an existing floor may be prohibitive.

A final solution is the installation of electrical heating mats that can be laid under carpets.

Where any under-floor heating is installed, floor coverings like laminates, tiles and carpets should have a tog rating no greater than 1.5. A high tog rating will seriously affect the ability of the system to heat the air above it.

The installation of under-floor heating will deliver efficiencies in heating utilisation only if it is suitable for the property and correctly fitted. Recouping the installation costs may take many years, but there is no doubt that a professional installation will substantially increase the value and desirability of the property and can be a wise investment.

It is always essential to ensure that any heating installations or upgrades conform to the current specific building regulations.

Wallpapering Behind Radiators – A Quick Guide.

To be honest, there comes a time when a decorating job cannot be put off any longer. The old paper has to come off.

Now, you might be planning a major renovation of your entire property. It is summer and the central heating is turned off. In which case, why not drain your entire central heating system, disconnect the radiators and lift them all off their brackets to ensure a really professional accomplishment at wallpapering. You could also power flush the system, install a new efficient boiler and install a magnetic filter all at the same time.

On the other hand, it does not always work as easily as that.

So how can you get around the problem of wallpapering behind a single radiator?

Ideally, the radiator should be disconnected from the system and lifted off its brackets in order to properly remove existing old paper, prepare the wall surface and remedy any imperfections and cracks. It would also be helpful to remove the brackets as well.

To do this you do not necessarily have to drain the whole central heating system. You can attempt to isolate and drain the problem radiator but that can be a very messy business. The radiator could well contain black sludge and inhibitor.  Not a good combination of contaminants to be slopping around, particularly in a room with fitted carpets.

There is a device that can be purchased from D.I.Y outlets that allows a radiator to be removed from the wall without draining. It is a clamp with a membrane attachment.There are two of these in a set.

The process involves attaching a clamp to the base of the radiator at each end close to the inlet valve and the lock shield valve.

Firstly, the heating is turned off and the radiator allowed to cool. Both valves are then turned off, isolating the radiator from the central heating system. Any pressure in the radiator has to be released through the bleed valve, and then this valve must be re-tightened to prevent any air entering the radiator. The nut leading from the inlet valve into the radiator is first slackened and then undone. When the valve is no longer attached to the radiator, it is pulled away from the coupling whilst simultaneously; the membrane attachment is slid across the revealed pipe opening leading into the radiator. The membrane prevents any liquid escaping and its attachment is then secured to the clamp.

The procedure is repeated at the opposite lock shield end, and when this has been accomplished, the radiator can be lifted of its brackets and removed.

It is possible to do this on your own, although with large, heavy radiators assistance is required.

The exposed area can now be decorated.

After decorating and allowing time for the wallpaper to dry completely, the radiator can be returned to its brackets and reattached to the system by reversing the isolation procedure. Finally, do not forget to bleed the radiator.

Of course, the method described above might seem more than a little daunting, even to the most accomplished D.I.Y enthusiast, and if that is the case, there are two options. Either get a professional plumber to remove and re-install the radiator, or decorate with the obstacle in place.

Certain schools of thought claim that what is hidden behind a radiator is not seen by the room’s occupants. If you hold that to be true, then wallpaper need only extend behind and to the sides of the radiator as far as is easily accomplished by the reach of the decorator’s hand. However, for the meticulous and those endowed with inexhaustible patience, such complacency is probably not an option. Ingenuity can come to the rescue.

First, make sure that the radiator is turned off and that the wall behind is cool. Soak any existing wallpaper with water and when it will scrape away easily, do so by attaching a scraper to a long handle or stick. After this is completed and the wall is dry, any imperfections in the wall surface can be sanded over using a sanding block attached to a stick. Finally ensure that no dust or debris is left adhering to the wall surface.

Now, take the sheet (s) of wallpaper that you intend to hang behind the radiator. If the sheets join to new wallpaper already hung parallel to the radiator, ensure that any pattern will line up when the paper is applied. Measurements now need to be taken from the horizontal edge of the existing parallel wallpaper to the brackets behind the radiator. Also measurements from the top of the skirting board to the bottom of the brackets and from top of the brackets to the bottom edge of existing new wallpaper above the radiator, or to the ceiling or window ledge, whichever being the case.

These measurements should now be transferred to the paper to be hung and corresponding cuts made to accommodate the brackets. The paper can then be pasted, and after appropriate time to allow the paper to become manageable, it should be carefully dropped behind the radiator and gently manipulated and smoothed into place using a radiator roller, a long palette knife or even a sponge attached to a stick.

Sometimes, a couple of pieces of thin string temporarily attached to the bottom of the section of wallpaper being hung can be gently pulled down from underneath the radiator to help ease it onto the wall without it creasing. Perfectionists may need to ease the wallpaper from the wall and re apply several times to achieve a satisfactory result. Once applied, the paper must given adequate time to fully dry before the radiator is turned back on.

You can now sit back and admire your accomplishment.