Installing heating

Wherever in France you have bought a property you will need some type of heating. You might not believe me if you have visited your dream property during the summer. Even Provence and Corsica have their cooler moments.

There are several ways for adding heating at the time of renovation. The method chosen depends partly on whether you plan to live in the property full time, or just as a holiday home.

General Advice

Almost all types of heating need to be inspected and serviced at least once a year. This includes having flues and chimneys cleaned, for example.

Open Fires and Wood Burning Stoves

Open fires look nice. That is their main advantage, and it is their only advantage. The net effect on the temperature of a house with an open fire is, apparently, zero. A large part of the heat from the fire goes out of the chimney. Worse than that, it sucks the warm air out of the house with it, which is then replaced by cold air entering the property through all the nooks and crannies around doors and windows, from the attic, and so on. All the new air is coming in from outside. The net result is that as much heat leaves the property as enters from the fire. Still, to be fair, there is an area immediately in front of a roaring fire which feels warm, even if you pay the price with a freezing cold bedroom.

Wood burning stoves are a very good way of heating. They burn wood very efficiently and a well fitted modern stove is environmentally friendly. 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). Although if an open fire is zero efficiency that still sounds poor(?!) Most of the heat actually stays in the house. Modern wood stoves reach a temperature at which most of the substances in the smoke are also burnt – the process is known as double-combustion, which makes the clean and non-polluting to use. In France twice as much forest grows each year as gets cut down, so there is no reason to feel guilty on ecological grounds. Wood stoves can produce typically 9 – 13kw of heat.

The large amount of heat produced is not spread evenly throughout the property, however, and this means the room with the stove in will be the warmest room in the house. Systems of ducting are available that can carry the heat from a ‘sealed in’ type wood stove to other parts of the house.

In principle it is possible to install a woodstove yourself. The stoves and chimney parts are readily available. But problems can arise. On more than one occasion I have heard of self-fitted stoves leaking large puddles of tar/creosote across the floor of the room. A smaller but important problem may be that the stove appears to be working well but is actually not working at full efficiency. If you fit your woodstove yourself, study the documentation that comes with the stove, especially the part concerning the position of the chimney pipes, and the regulations that cover the distances of the stove and flue pipes from inflammable surfaces, and how to pass a chimney through a roof space. These are important for both efficiency and safety.

Woodstove flues, as with all chimneys, need to be cleaned at least once and often twice each year. If you read your insurance documents you will almost certainly find this to be a requirement of your insurance cover.

Central Heating

Central heating usually runs on oil or gas. Gas is normally town gas (i.e. arrives at your property through a gas supply pipe) only in the larger towns and cities, whereas propane in tanks is used elsewhere. Gas tanks can be buried in your garden, whereas oil tanks should stay above ground, and will need protection from the elemnts, and concealing. Oil is usually cheaper than gas to heat with, but town gas is cheaper still.
Installing a central heating system will begin with a full assessment of your property requirements. This assessment will be performed by the plumber or a heating engineer. The total heating power needed, and the heating levels required room by room, depends on several factors including the method of construction, the number and sizes of doors and windows, the ceiling heights, the presence of proper insulation and so on. The heating engineer will have a computer programme that can calculate the heating levels required for optimal performance for your particular property.

An over-powerful system is not a good thing, because this can force the boiler to start and stop all the time, causing unnecessary wear and tear. It needs to be the ‘right’ system to be efficient and effective.

Oil / Gas Boiler with Underfloor heating

Underfloor heating now is very different to underfloor heating that was installed 10-20 years ago. Nowadays the heating works at low temperatures – the floor is at a temperature around 28 centigrade – so the floor doesn’t actually feel warm to touch, or give rise to swollen ankles and hot draughts.

Many more pipes are used nowadays, so that the entire floor area can be heated without having localised hot spots. Insulation is placed under the heating pipes to prevent the heat from travelling down into the ground.
Although impressive, we have never used this system in our own renovations. This was because I believe that if the heating is on all the time during the winter, underfloor heating is very efficient, but for more intermittent use the ‘thermal inertia’ (time spent reaching temperature and cooling down again) of the floor would make it less useful. So I was less sure how well it would work in conjunction with a wood-burning stove, which provides a significant part of our heating. This is an area in which I am happy to be corrected if I am wrong.

If you are installing underfloor central heating, this must be planned early on in the project. Some specific points to consider:

  • Wooden flooring is not suitable for installing over underfloor heating
  • It is important to have insulation underneath the ‘in floor’ heating system
  • The mortar screed on the floor must be laid carefully, because the heating pipes must be completely surrounded by the flooring material, with no air gaps. Usually a specialist will be necessary to lay this properly. They will use a ‘pour it on’ type of screed, that is very liquid when added, self levelling, and quickly sets hard. This has the additional benefit that you get a completely flat surface for tiling on.

Central Heating using Radiators

In areas which don’t have access to town gas, oil based heating is still often the most economical solution in France, despite the recent price increases.

We were lucky enough to have several solid cast iron radiators left over from an earlier renovation, so were able to use them. The plumber had no particular difficulties attaching old radiators to a new heating system. A central heating system using new radiators is still less expensive than a full under-floor heating stystem.

Radiators are less satisfactory than underfloor heating in one main respect. The sensation that yo get of cold in a room is due to ‘thermal gradients’ – that is, areas of the room that are at higher temperature than other areas. This creates air movements and drafts, and gives rise to the perception that some areas are colder.

See detailed information including an introduction to floor heating installation at hot-floors.com, a leading supplier of electric under floor heating in the UK

Geothermal Central Heating

Geothermal central heating is a system in which subterranean heat from the land around the property is used to provide the heat for the property. This is an efficient system, and is quite popular in France and several other countries. A viscous liquid is piped around the land surrounding the property, in trenches dug to a depth of about a metre. This fluid reaches a temperature of about 15 centigrade, all the year around. This fluid is then passed through a heat pump (similar to that used by a refrigerator, but operating in reverse) which raises the temperature to 45 centigrade. This is sufficiently warm to be used for heating – almost always in conjunction with an under floor heating system, since this is better suited to such low temperature water.

The main ongoing running cost is the electricity that drives the pump, to force the liquid through hundreds of metres of buried pipes. Each kilowatt of energy used by the pump gives rise to three kilowatts of heating energy. So heating bills should be much reduced, typically by a factor of three.

Installation costs of geothermal heating are higher than with other heating systems, partly because of the cost of digging up a large area of land to lay the pipes. See also reduce your heating costs with a pompe a chaleur.

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 fuel 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 sudden surges in price than gas and oil. In other situations it is likely to be less often recommended.

If you are installing electric heating you will need to ensure you have a adequate supply of power to the house (see electricity section).
We do sometimes use oil-filled electric radiators for heating one of our rental properties, in conjunction with a wood burning stove. These work very well, need no installation skills (ours plug in) and are cheap to buy.

One response to “Installing heating”

  1. David Greenfield

    You didn’t mention the cost of adding a heating system. I’m curious as to what the $ amount is per square meter. I am thinking of buying a very old Chateau in the South of France, but it states only that there is a “boiling room” in the basement with the kitchen. Will this be an effective way of heating a 1000 sq. meter building. And if not, what would you recommend. Also, it’s a historical landmark, so will I even be able to install a new system? Any advice you can offer would be greatly appreciated.

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