So you may be thinking about changing or upgrading your heat source. We do not install heat pumps but knowledge is power and maybe this will help.
So you have probably seen the adverts all over the press and social media advertising installation of Air to water source heat pumps (Pompe a chaleur) for as little as one euro (If eligible). This is because the French government has to be seen to be reducing its carbon footprint but they do not appear in my opinion to care about your electricity bill or if the system actually works properly for your home.
The guidance below is with respect to people thinking about replacing an old or relatively new boiler and will give you some pointers as to whether an air source heat pump is correct for your property. Of course an installer is going to be able to give you much more qualified advice once he has been able to inspect your system. Here are a few boxes to tick that should help you decide.
Normally you can only consider using your existing heating system with an air source heat pump when:-
By that I mean it uses water as the heating medium through some form of boiler.
The better insulated and air tight your home is, the more comfort you get from each unit of heat. You cannot blame the heat source if you cannot retain the heat that it produces.
Heat pumps have heat exchangers which have very narrow waterways, in order to “scrub” as much heat from the refrigerant as possible. These waterways can therefore become easily blocked by suspended debris in the heating system. You can add a strainer in the system to protect the heat exchanger, but if you have a dirty system this will constantly become blocked and produce “nuisance trip outs” which will prevent your heat pump from operating. All manufacturers recommend a system clean before installation and many will invalidate the warranty if not done. See our powerflushing page.
If you have a radiator system you will almost certainly need to increase the size of your radiators assuming they currently work on a heating system providing 70 °C flow water temperatures or above. This is the biggest problem faced by most of the boilers replaced with an air source heat pump.
A cylinder designed for preheating the domestic hot water with flow temperatures typically obtained from an air source heat pump. If you have a seperate water heating system this is not an issue.
As always, the best way to determine whether you can utilise your existing system, is to speak to your installer. They should be able to advise whether using your existing system or part of it, would be a cost effective option in the long term.
I had a Daiken Low temperature Air Source pump fitted, plumbed into exsisting radiators that were originaly heated by a coal fire back boiler. The system is at the side of the house away from the bedrooms and is loud enough to be heard in those bedrooms. The radiators never get any warmer than tepid (I can sit with my bare back against them) and the cost seems excessive compared to the coal fire costs.
Heat pumps are suited for new build, well designed and insulated properties - water underfloor heating works at the lower temperatures and is therefore ideal for heat pump applications. I have experienced UFH in two properties, one was a modern well insulated house and was economical and lovely to live with, the second was a converted barn and it was cold and not sufficient. I would have it in a new house, not in a conversion or an older property without good insulation.