Keep existing oil boiler and rads and install new underfloor heating with heat pump

986s

Hi,

Any opinions welcome. I am about to purchase a house that was built in 2000 that is quite large (4,000 sq ft) which has a recently renewed oil boiler and good radiators upstairs and downstairs (C1 BER).As part of renovation work I will be taking up all floor coverings downstairs (tiles/ wood floors) and replacing kitchen, dry lining internally all external walls, pumping existing cavity and adding new triple glazed windows.

My question is would it be unusual to add low profile underfloor heating (LoPro max) for downstairs and combine this with a new air to water heat pump? Bear in mind the majority of the house floor area is downstairs approx 2600 sq ft. I would still keep the radiators downstairs and upstairs running off the oil boiler and just use the new heat pump to heat the underfloor downstairs and for hot water needs. The current oil heating is zoned upstairs/downstairs/hot water. Would I still receive the SEAI grant for the heat pump if I left the existing oil boiler in situ running the rads?

My logic is let the heat pump work away to heat the down stairs under floor system/ provide hot water and still have the option to use the rads with the oil boiler if things needed a boost or if there was a prolonged cold snap to take the pressure off the heat pump when temps dip.

Penn

I don't know about the grants, but yes it would be unusual.

You're doing a lot of work at significant cost to install a heat pump and underfloor heating. Let's say in 10 or 15 years your oil boiler gives out, parts become too expensive, taxes on oil go too high etc. Then you're stuck with an oil boiler heating system which needs to be replaced, and an undersized heat pump. Therefore you have two heating systems installed which aren't capable of heating your house.

You're far better off installing a properly sized heat pump which can cater for proper underfloor heating downstairs and rads upstairs (or similar arrangement, rads throughout downstairs or whatever). You shouldn't need what is essentially a full second central heating system for a boost or to take pressure off the main one. Small supplementary heaters, or a small stove etc could provide an extra boost if required, but even then you're better off going for additional grants and upgrading the building fabric to minimise heat loss to begin with. (Sorry, re-reading your post, you're already upgrading insulation throughout, in which case again, you shouldn't need two central heating systems regardless).

BryanF

~400m2 house, built in 2000, you’ll probably need 2 heat pumps.. suggest living in the house for a year or two and assessing heat loss/ thermal comfort and heating bills etc. Your house would need a building envelope review before sizing ufh or heat pump etc.

Yellow_Fern

Why bother with a heat pump? By all means upgrade your system and make it heat pump ready as that can improve efficiency and system quietness, but not seeing the need for heat pump. Id rather invest in airtightness measures and mechanical heat recovery.

By the way, in terms of saving the planet, for many, the main gain of a heat pump is its high efficiency when set up well as the Irish grid is as about as carbon intensive as just burning gas at home.

986s

Thanks for opinions folks- just for clarification house size is 4000 sq ft not sq m with the majority of the footprint downstairs approx 2600 sq ft. It’s a story and a half dormer type house which is currently similar to my current house. As part of renovation works will be taking a whole house view of things i.e. upgrading insulation, air tightness, windows, MHRV and solar PV.

In my current home I’ve done significant work myself in insulating and sound proofing the first floor (not hollow core) and would hope to do the same in the prospective purchase.

I like the feeling of underfloor heating and think it would be a worthwhile undertaking placing a low profile UFH system in while all floor finishes/ kitchen are being replaced. Just trying to work out the budgetary aspect of this- can I expect the SEAI grant for a heat pump installation if if I leave the current heating system in situ?

karl k

It is hard to believe that we need to update our housing stock from the 2000s to this degree, Having worked at the electrics and plumbing of similar large building s back then it saddens me that you have to. I believe you would have more value if you bought a much older period house in need of a deep retrofit or a brand new or self build passive or A1 house. I think the role of HVO will play a major part of heating similar 2000s oil dependent houses, BE careful to get a surveyor who can for see your future energy costs and the payback on the tech equipment and investment on your upgrades, threat a house of your size as if it is a deep retrofit you must look at the thermal envelope first remove all thermal bridges achieve a u value of below .1 for walls and roof, an air tightness of below 1 then and only then mhrv after which other tech, at this stage pv solar 6kw with electric uf heating if you want to feel it on you feet all fireplaces must be changed to external vented stoves. Then you will not need a heat pump your house will more or less be at passive standard and you will be able to maintain an internal temp of 21 degrees without oil or heatpump.