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Question to a heating engineer

To conclude the file boilers, HandymanDuDimanche has called on a heating specialist to answer your questions. Mr. Lezot has thus lent himself to the game by trying to find a solution to each of your problems.


I live in an old house and I will replace the old gas boiler (it must be at least 35 years old). The radiators in the house are cast iron and just as old as the house. A friend advises me to install thermostatic valves on each radiator, but another tells me that this is not necessary on cast iron radiators. What is it exactly?
(Marie L.)

Question to a heating engineer: engineer

The cast iron radiators are the strongest because they never break, unlike steel radiators that pierce frequently (in three years, I had to replace thirty radiators sheet metal and perhaps a cast iron on 10000 homes). In addition, the cast iron radiators retain and emit heat longer, once the boiler has stopped (however, they take a little longer to heat than normal radiators). You do not have to add thermostatic faucets. These are used to keep a constant temperature in the room where they are installed. They can be installed on all types of radiators. However, do not put in bathrooms, and toilets. This serves for the living room, the bedrooms but also for the kitchen. This is a comfort not insignificant especially when the room thermostat turns off the boiler at 21 degrees and turns it on again at 19. A thermostatic is very precise, so you can have 19 degrees in the bedrooms and 21 in the living room. It should not be used everywhere because if they all go out at the same time, there will be more water circulation in the radiators, which may damage the pump. Count 40 euros for a model upscale or less for the simplest faucets. They are very useful and provide a significant additional well being, plus they give you the right to a tax credit. I have also installed several at home and do not regret my investment.

What do you think of a reversible heating-air conditioner with remote control?
Cost and consumption for individual house, to heat 60 m2 in the south-west (Tarn and Garonne)?
Right to the tax reduction?
(Colette N.)

A reversible air conditioner is good, but especially for the cold: it does not warm as much as a radiator. If you live in the South West this should be enough. The heat goes from the bottom to the top, and as this type of fixture attaches to the top of the walls, they have a harder time warming the room than the radiators. I can not estimate your consumption, but one thing is certain, it works on electricity. Even if it does not consume a lot of electricity, you should know that electricity is quite expensive. When to the tax credit, it does not affect this type of devices.

I have steel radiators at home and I installed a new aluminum radiator. A friend who tinkered a lot told me that having radiators of different material could damage my boiler because a hydrolysis phenomenon can appear. Thank you kindly inform me about this phenomenon.
(Alexis G.)

Mixing several metals in one installation is not very advisable, as this can lead to the formation of sludge in the radiators. But rest assured, in a house of average size this is not very serious. The boilers are normally made of cast iron so very solid, the mixture should not be a problem. When the hydrolysis phenomenon, your friend is perfectly right, it will take place but will not damage your boiler.

I would like to know if a city gas boiler can be used in butane gas and if there are changes to be made?
(Luis P.)

Theoretically it is possible to change gas without any modification on your boiler, because the city gas and butane are both in the same form. After that may vary depending on the model of your boiler and its age. For more security, you should contact a specialist by giving him the references of your device.

What are the steps to take to maintain a boiler?
(Robert H.)

If you are not a handyman, the best is to use a specialized company that will provide you with good guarantees. If you want to take care of it alone, before you dismantle anything, always close the gas or fuel. For gas boilers, you can clean once a year the ionization probe (a metal rod surrounded by porcelain), and the thermocouple. You can also scrub the ramps that release the gas, after having completely shut down your boiler for two days. For oil-fired boilers, the operation remains the same except for the thermocouple, in the place of which there is sometimes a light sensor.

What are the first things to do when a boiler is not working properly?
(Christmas F.)

When a boiler does not start anymore, it is necessary to start by checking if the ignition arc is done well (normally you must hear a noise well characteristic of the boilers). If the arc does not come on, its electrode or ionization probe is dirty. They must be cleaned. The ignition transformer can also be broken, which is all the more rare; he must be replaced by a professional. The failure can also come from leakage of thermocouples that lose gas and therefore no longer activate the valves, which prevents the boiler from operating.

Be very careful when dealing with a gas boiler, after 2 or 3 ignition tests, allow the boiler to rest for 5 minutes for ventilation.

As for oil boilers, know that after a few ignition tests, a puddle of oil can form inside the boiler and catch fire when the boiler will restart, which may cause a dangerous explosion.

Whatever you do on a boiler, always be very careful and the slightest doubt do not hesitate to call a professional!


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