Installing heating, central heating, geothermal heating and woodburning stoves

Installing Heating

Wherever you live in France you are going to need heating of some form in your property. I'll repeat that in case you have only visited your dream property in the summer. There is no part of France in which a house will be comfortable all year around without any heating. Even Provence and Corsica have their cooler moments. There are several popular options for heating a building at the time of renovation.

General

Whichever type of heating you choose it will need to be inspected and serviced a least once a year. This will include cleaning of flues and chimneys where appropriate.

Open Fires and Wood Burning Stoves

Open fires look very nice. That is their main advantage, it is also their only advantage. The net effect on the temperature of a house with an open fire is, I am told, zero. Most of the heat from the fire goes straight out of the chimney. Not only that, but it sucks air out of the house with it, which is replaced by cold air entering through all types of nooks and crannies around doors and windows, the attic and so on. All coming in from outside. Net result - as much heat leaves the property as enters from the fire. Still, there is an area immediately in front of a roaring fire which feels warm, even if a cold bedroom is the price to pay.

Wood burning stoves are a very good way of heating, being highly efficient and essentially environmentally friendly. I understand that wood burning stoves are nine times as efficient as an open fire (i.e. three times as much heat with a third of the wood burnt). And most of the heat stays in the building. Modern stoves reach temperatures at which most of the substances in the smoke are also burnt, in a process called double-combustion, making them clean to use. In France twice as much forest grows each year as gets cut down, so no reason for guilt on ecological grounds. Wood stoves  can produce typically 9 - 13kw of heat.

The heat is not evenly distributed through the property, however, and tends to cause the room with the stove in to be much the warmest room in the house.

In principle it is straightforward to install a stove yourself. Certainly the stoves and chimney parts are easily available. But problems can and do arise - on more than one occasion I have known self-fitted stoves to leak puddles of tar into the room. A lesser problem will be that the stove appears to work fine but is actually not working at its full efficiency or as it should. If you do fit your stove yourself, read the documentation that comes with your stove carefully, especially regarding the positioning of the chimney pipes, and the various regulations concerning distances of the stove and flue pipes from inflammable surfaces, how to pass a chimney through a  roof  and so on.

Wood burning stove. The fan on top of this stove generates electricity from the heat differential between its bottom and its top, which turns a fan which helps the air circulate. The kettle makes a nice cup of coffee

Stove chimneys as with all active chimneys will need cleaning at least once and probably twice each year. Read your insurance documents - this will almost certainly be a requirement of your cover.

 

Central Heating

Central heating usually uses oil or gas as fuel. Gas is typically town gas (i.e. arrives at your property through a gas supply pipe) only in larger towns and cities and is Propane in tanks elsewhere. One important difference is that gas tanks can be buried in your garden, whereas oil tanks stay above ground and need protection and concealing. Oil is currently a cheaper fuel than gas to heat with, but town gas is cheaper still.

Any central heating installation will start with an assessment of your property by the heating engineer. The total power required, and also the levels required in each room, depend on several factors - method of construction, number and size of doors and windows, ceiling heights, presence of insulation and so on, and the engineer will have a computer programme to calculate the levels required for optimal performance in your property. Note that an over-powerful system is not a good thing, due to the boiler being forced to stop and start all the time. It needs to be the 'right' system to be efficient and effective.

 

Oil / Gas Boiler with Underfloor heating

I should explain that underfloor heating nowadays is fundamentally different to that of 10-20 years ago. The heating works at low temperature and the floor is at 28 centigrade, hence does not feel warm to touch and doesn’t give rise to swollen ankles and hot draughts.

Many more pipes are used which enables the entire floor to be heated without having hot spots. Insulation placed under the heating pipes prevents the heat from travelling down into the ground. This gives rise to a claimed 10% saving in heating costs.

We didn't use this system in our own renovations. This was because I think that if the heating is on all the time during the winter this heating method is very efficient, but for more intermittent use the ‘thermal inertia’ of the floor would make it less useful. Hence I was less convinced how well it would work in conjunction with a wood-burning stove. This is an area in which I am happy to be corrected if I am wrong.

If you are having underfloor central heating this must be planned early on in the renovation project. Specific points to consider include:

• Wooden flooring is not suitable for this method of heating
• Insulation underneath the 'in floor' heating system is crucial
• The chape (screed) on the floor must be added very carefully - the heating pipes must be completely surrounded by the flooring material, with no air gaps. Usually a specialist will be required to perform this. They will probably use a 'pour on' type of screed, that is liquid when added and sets hard quickly. This has the added benefit of giving you a completely flat surface for tiling.

 

 

Central Heating using Radiators

In areas without town gas, oil is still usually the most economical solution in France, despite recent price increases.

We were lucky enough to have inherited several original cast iron radiators from an earlier renovation, so used them. The plumber had no difficulties in attaching old radiators to a new heating system. central heating with newly bought radiators is still cheaper than a full under-floor heating stystem.

Radiators are less ideal than underfloor heating in one key respect. The sensation of cold in a building is largely due to ‘thermal gradients’ – that is, areas that are at a higher temperature than others. This creates drafts and the perception that some areas are colder, although the actual temperature may be sufficiently warm.

Geothermal Central Heating

System in which subterranean heat from the garden is used to heat the property. This is an efficient system, and currently quite popular in France, and several other countries. Essentially a liquid is piped around the land surrounding the property at a depth of about one metre, where it reaches a temperature of about 15 centigrade, all year around. This then passes through a heat pump (similar to that used by a refrigerator, but operating in reverse) which raises the temperature to 45 centigrade. This is then used for heating, ideally with an under floor heating system, since this is better suited to such low temperature water.

The main significant running cost is the pump which forces the liquid around the garden. Each kilowatt of energy used by this pump gives rise to three kilowatts of heating energy. So heating bills should be much reduced, typically by a factor of three.

Installation costs are higher than with other heating systems, principally because of the cost of digging up a large area of land to lay the pipes.

 

 Electricity

I don't personally know anyone who has electric heating in France.  There are several companies that promote their own 'super efficient storage heater' systems. These cost as much as any other central heating system to buy and install, but they do avoid the problems of storage that you may have with oil and gas.

In towns and cities, where buildings are smaller and warmer, and in new-built properties with high levels of insulation, electricity can be very economical and is less subject to suden surges in price than gas and oil.

We do use oil-filled electric radiators for heating one of the rental properties, in conjunction with a wood burning stove, and they work very well, need no particular installation skills and are cheap to buy.