Advice from heat pump users in Edwardian/Victorian homes.

[RenovatingEdwardianhouse]

We are hopefully mid purchase of an Edwardian semi. It needs a new boiler, we are in Greater London. By 2025 no new gas heating can be installed here. I’m looking for some advice around air source heat pump systems. Especially from anyone who has installed one in an Edwardian or Victorian house. Did you add extra insulation? Did you go for radiators or underfloor heating? What would you do again or differently? Thanks!

Have a look at wundafloor, it is overfloor underfloor heating (IYSWIM) I have a period property and in comparison to rads it is a world of difference in keeping an older house warm. We also use less energy than in our last period house as we don’t have cold/hot spots. We have ours connected to oil but are about to switch to a mix of renewables (PV and wind). The issue with heat pumps as I understand is that unless you get the pipe diameter right for UFH, it can cost a lot in electric costs do do a lot of research. You can always connect UFH to a gas boiler now (I’m not sure increases elec costs is the way to go for the next 18mths or so) and switch out to a an alternative as the technology improves?

Watching as currently debating exactly the same for ours

there was a long post about all this on similar house on our local fb group....generally conclusion was dont bother....too expensive and the high running costs and you can never insulate enough for it to work well.

You need to look for specialist advice. For an air source heat pump to be effective your home needs to be insulated to the max. Doable but very expensive and will also reduce room sizes. It's very hard in an older home to achieve the level of insulation required. You need to go into it with your eyes very wide open.

I believe you need about 6 inches of insulation which will make all your rooms 6 inches smaller. Every room will also need new windows and a complete redecoration. On a typical London house, the smaller room sizes will make quite a difference.

I have no idea what the government actually think is going to happen to the 1000s of Victoria / Edwardian houses with no insulation if they ban new gas boilers. Ideally, it would be possible to put external insulation on whole rows of houses at once, but that would change the look of the houses & is also expensive and complex. But the policies are a MESS and there is no easy or sensible solution.

There is also a possible issue with older houses and insulating them as they were built to rely on air flow through the building to remove excess moisture and insulating will block drafts and cause damp so you may need to put some sort of ventilation system in too.

Six inches of insulation! 😱 Crikey, we certainly weren’t advised that at all.

We seriously looked into an air source heat pump for our Edwardian terrace OP. We were already putting in underfloor heating, new/bigger rads, double glazing and insulation so didn’t need to account for those additional costs, which is often what can make it overly expensive. We were without radiators for the first winter after we moved back in and the house is sufficiently insulated that we weren’t cold iyswim.

We didn’t install one in the end as our garden isn’t big (long) enough for a bore hole (ground source heat pump, which was my preference) and the air source units are still quite loud (they need to be a certain distance from any windows which open) and large, so would dominate our small garden. I also struggled to actually find a supplier.

However, our hope is that the technology will come on a fair bit in the next few years making the air source units more compact and quieter, at which point we’ll look to retrofit. Once they’re closer to an air con unit size one could install this on the roof for example. Would be interested to hear from anyone who has successfully done this in a similar property.

We had an ASHP fitted last year. Ours is a stone built property. Prior to this, the only source of heating was one coal fire with a back boiler for hot water. We have had UFH installed and wall insulation to all internal surfaces of external walls. We have lost around 4-6 inches from these walls. There are much thinner insulation products which give equivalent insulation values but they are very expensive. The biggest problem with the insulation was finding somebody to install it. Couldn't find anybody ( Greater Mcr). DH ended up doing it himself. Massive job for a novice.
I have (hopefully) attached a photo of the plant installed for the ASHP. We have a cellar that we were able to use as a plant room but you need to be able to house this somewhere in your home. The ASHP is in the garden. We are not on mains gas and didn't want to go down the LPG or oil route. It helped that our house was a blank canvas. Early days yet but so far so good.

thanks for the information. 6 inches of insulation is just not possible in the house we are buying. But then the prices of gas are just frankly sickening at the moment. What do we do? The house is bigger than where we are now, and will require more heat. Can anybody advise? Are we best off just to get a new gas boiler? Which I have a feeling will back fire within 5 years or so. Change from rads to underfloor? Also if anybody can advise who to ask for expert help that would be much appreciated. The house is in dire need of renovation so we would have to start work fast, also don’t want to have to undo work we pay for now later on. So any ideas around that welcome too.

I've had both internal and external wall insulation installed on our house. 6 inches of internal wall insulation is a lot. I had an external company do a retrofit review on the house, and the general consensus was that 50mm of insulation was effective, 100mm was better but was not twice as effective etc.
Have 100mm of eps wall insulation on the external walls on the upper floor (limited to that only, conservation area).
As well as insulation, one of the best things you can do is minimise draughts - no original wooden floor boards won't be effective, unless very thoroughly insulated from below. We upgraded our wooden floor to a tiled floor and just doing that massively reduced draughts - the skirting boards were taken up, floor screed, plywood basis down plus tiling. I filled all the gaps on the bottom of the walls when the skirtings were up, so that underfloor draughts into the house were largely eliminated. Still have good subfloor ventilation, though.
I looked into underfloor heating but we had already done the rest of the ground floor and I understood that u/floor heating would work best if the whole ground floor was done - it would give a much more even temperature. If you did underfloor heating now, even if you install a gas boiler, it would be a much easier switch to ASHP in the future. As a piecemeal renovator, there are big advantages to doing the whole ground floor in one go - different floor levels with different floor surfaces has been the bane of my life!

Just to be clear, we haven't installed insulation that is 6 inches thick. We used insulated plasterboard which is 72.5mm thick. That is attached to a track and channel system attached to the walls which intentionally creates a void between the wall and the insulation. Because the external walls are so uneven, we lost yet more space where the walls were levelled up with the insulated plasterboard.
Is external wall insulation an option for your house OP?

We looked into it for a 1930s house. We were promised the world by a number of cowboys and then had a call with one of the early adopter/installers. Despite redoing all the roof insulation, installing UFH on the ground floor, replacing all windows and much more, he said we’d struggle to keep it warm. He actually advised us to get a gas boiler that can convert to hydrogen in due course with an adaptor.
Shame but there are very few new homes where we live. I don’t know how urban Britain is going to cope when boilers are banned.

We have one in something we have built recently so relatively well insulated albeit single storey. Its useless - costs an absolute fortune in winter and we are not even warm. Uses over 100kw hours per 24 hours in winter and imagine that at current and predicted prices Also spoke with one of the manufacturers of a prototype hydrogen boiler and he said they are 20 years off general release. ASHP might be ok in passive conditions, smaller houses or those in blocks but useless otherwise

100KWH in 24 hours is massive. In winter the highest our ASHP used was 28KWH in 24 hours. It is currently using 7 KWH in 24 hours.