We live in a 1980s four-bedroom detached house. The time has come for new central heating.
The current system is a mild revision of the original heating installed when the house was built, and this revision was largely to replace a life-expired boiler:
It is time for a new system. We want to reuse the existing radiators and heating circuit, as we cannot face the disruption needed to replace them. We are still a couple of years away from replacing the existing double glazing with windows with heat-reflecting glass and we still have more work to do on insulation. For all those reasons, an air-source heat pump is not an option, so it will be a case of powerflushing the system and fitting a new natural gas boiler. However, I am willing to replace everything else if it makes sense to do so.
The design and installation of a new system is, of course, a job for a professional. However, I want to be an informed consumer, hence this post.
It seems that the biggest choice is what to do with hot water. We have a large jacuzzi in one bathroom and a pumped mixer shower in the second bathroom, so I suspect that a hot water tank makes more sense than a combi. If we stay with a tank, priority domestic hot water seems to be the way ahead, so I presume that will mean a new tank with a bigger coil and perhaps a smaller capacity (the current tank seems too large despite the current bathrooms). PDHW will have the advantage of getting rid of the three-way valve with its failure-prone microswitch. If we are replacing the tank anyway, does it make sense to go unvented to give us greater hot water pressure?
So far as the radiators go, I'm not especially keen on pressurising an old circuit which has been unpressurised for the last 42 years. I do not care about the space used by the header tank, which is in a corner of the loft out of the way. Is the best option to stay open-vented, or would it be better to have a system boiler and pressurise the radiators?
I want every radiator on a TRV, so a bypass is needed. Whilst the system is being upgraded, is it best to replace the existing TRV bases or is it acceptable to leave them until they jam or leak?
I want smart controls that will modulate the boiler properly, as well as a boiler that will do dual temperatures for PDHW. I'd rather have OpenTherm on the boiler so that I have flexibility in which controls to use. I have looked at Evohome, though maybe there is a better alternative.
Is fitting a magnetic filter worthwhile, or is this just an expensive upsell for a limited extra warranty on the boiler?
I would welcome recommendations for boiler brands and for contractors willing to do this job in Bedfordshire. I am not interested in someone who is going to tell me to put a new boiler into the current flawed system rather than redesign the system properly using modern principles.
The current system is a mild revision of the original heating installed when the house was built, and this revision was largely to replace a life-expired boiler:
- non-condensing fan flue boiler
- open vented
- vented hot water tank in an upstairs airing cupboard
- TRVs on half the radiators
- no bypass in the heating circuit
- Y plan
- basic controls - bimetallic room thermostat, bimetallic hot water thermostat, 7-day timer
It is time for a new system. We want to reuse the existing radiators and heating circuit, as we cannot face the disruption needed to replace them. We are still a couple of years away from replacing the existing double glazing with windows with heat-reflecting glass and we still have more work to do on insulation. For all those reasons, an air-source heat pump is not an option, so it will be a case of powerflushing the system and fitting a new natural gas boiler. However, I am willing to replace everything else if it makes sense to do so.
The design and installation of a new system is, of course, a job for a professional. However, I want to be an informed consumer, hence this post.
It seems that the biggest choice is what to do with hot water. We have a large jacuzzi in one bathroom and a pumped mixer shower in the second bathroom, so I suspect that a hot water tank makes more sense than a combi. If we stay with a tank, priority domestic hot water seems to be the way ahead, so I presume that will mean a new tank with a bigger coil and perhaps a smaller capacity (the current tank seems too large despite the current bathrooms). PDHW will have the advantage of getting rid of the three-way valve with its failure-prone microswitch. If we are replacing the tank anyway, does it make sense to go unvented to give us greater hot water pressure?
So far as the radiators go, I'm not especially keen on pressurising an old circuit which has been unpressurised for the last 42 years. I do not care about the space used by the header tank, which is in a corner of the loft out of the way. Is the best option to stay open-vented, or would it be better to have a system boiler and pressurise the radiators?
I want every radiator on a TRV, so a bypass is needed. Whilst the system is being upgraded, is it best to replace the existing TRV bases or is it acceptable to leave them until they jam or leak?
I want smart controls that will modulate the boiler properly, as well as a boiler that will do dual temperatures for PDHW. I'd rather have OpenTherm on the boiler so that I have flexibility in which controls to use. I have looked at Evohome, though maybe there is a better alternative.
Is fitting a magnetic filter worthwhile, or is this just an expensive upsell for a limited extra warranty on the boiler?
I would welcome recommendations for boiler brands and for contractors willing to do this job in Bedfordshire. I am not interested in someone who is going to tell me to put a new boiler into the current flawed system rather than redesign the system properly using modern principles.
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