Does underfloor heating to replace carpets in 18th Century stone property with beautiful old windows (and therefore draughts) make sense?

[frogflower]

We're in the process of purchasing a large stone house mostly built in the 18th century. It's currently carpeted though out, but appears to be floorboards under it all. The windows are beautiful, mostly arched and plentiful. They're in good condition for the most part, but single glazed. The ceilings are all very high and most rooms have tall skirting boards.
Does it make sense to do above floorboard UFH, with a new floor above it, and therefore raising the floor? Will it compensate for the poor window situation? We'd probably put in a heat pump.
We are 100% clueless on owning an old home, but it is in good condition in general, but I'm mostly concerned about heating. They spend around £5000 a year on bills (it's a 5 bed).

Any and all advice appreciated!

 

[fernicarry]

UFH is just a different way of delivering heat to the building. Think of it like a big radiator lying on the floor. There's no magic involved, you still have to pay for the heat that goes into the building.

One reason UFH is often said to be ideal for HP's is because the very large emitter area can mean that you can deliver the same heat "energy" with a lower flow temperature. HP's like low flow temperatures, in fact they require them. There are other factors like having a slab with high thermal mass to compensate for daily variations in heat demand whilst allowing the heat source to run at a nice slow steady rate, also good for efficiency/economy.

Old buildings with high rates of heat loss, need high rates of heat input and that generally means high flow temperatures -- or infeasably large radiators. Windows are quite a large fraction of the heat loss, something like 25% or more. If you, like me, want to keep your original single glazed sash windows then you are going to have to live with the high heat loss and that will almost certainly rule out a HP as being practical never mind economical.

Search the forum for other discussions on HP's. A HP is unlikely to me meaningfully less expensive to run than a gas boiler on mains gas whilst costing an awful lot more to install. You would really only choose a HP if electricity was your only energy source or govt. policy forced you to do so (point of use combustion heating is already banned in Scotland for new builds, and RoUK appears to be going in the same direction), but it would still only work if the heat loss in the building was reduced to a much lower rate i.e. lots of work on air tightness and insulation.

 

[Cubist]

Must admit that the only time UFH has made any sense at all to me is when its used in rooms with solid floors finished with tile. The thought of using it with suspended wooden floors just doesn't make sense insofar that, unless the heater pipes are fully isolated from the void beneath the floor then much of the heat will be lost to the airflow needed to ventilate it and prevent rot. Also, timber floorboards of any kind are pretty poor heat conductors - until they catch fire - so onward transfer of heat to the room above would, in my opinion, be very poor. There is a further consideration insofar that UFH could induce buckling of the floorboards and perhaps to the point of failure. Frankly I suspect your best strategy would be to consider insulating the underside of the floor to limit cold penetration from that route and improve the efficiency of the space/air hearting systems in the rooms concerned. there have been several disuccions in this forum recently concerning how to go about this and what materials can be used.

 

[frogflower]

I really appreciate your inputs on this. I had hoped it might help, but probably not. The current owners say they keep it at 20c comfortably, which is reasonable. We often let our current home stay colder than that and pay £2500 for a modern 5 bed.
The windows are mostly arched 3 panel windows. I cant imagine the cost in replacing /improving them. The downstairs does have solid wooden shutters on the windows, so I guess closing those at night and if out for long periods of time?? I guess sticking with carpet over the ground floor will also help? It's probable the floorboards are a mess anyway....

 

[Cubist]

We use internal shutters here in several of the rooms and they work extremely well and far better than even heavy curtains. Carpets will be a big help too, certainly in terms of reducing cold air penetration from the floor voids but longer term you may be wise to consider the insulation strategies that may permit you to expose the floorboards as others have done.

 

[frogflower]

We use internal shutters here in several of the rooms and they work extremely well and far better than even heavy curtains. Carpets will be a big help too, certainly in terms of reducing cold air penetration from the floor voids but longer term you may be wise to consider the insulation strategies that may permit you to expose the floorboards as others have done.

Thank you, that's good to know. If we're redecorating the house (lots of wood chip wall paper, but also lots of cornices, picture rails etc), can we/should we look at insulating the walls internally?

 

[Cubist]

It's certainly feasible, with some compromises, and careful design but the real questions are Is it necessary/advisable and does the layback argument work. You need to get a proper evaluation of the thermal efficiency of the house together with some clear guidance concerning how much benefit may accrue from any given approach to its insulation.

 

[Itchinfilth]

Raise the floor levels and you'll lose the intended proportions of the room and you'd have to take off the tall skirtings and risk damaging them or keep insitu and lose their height. Insulate walls, potentialy lose or diminish the detailing you mention. These will likely be the features which drew you to a period property in the first place and IMO should be kept at all costs. It sounds an intriguing property by the way, windows sound great.

 

[Stevers]

The problem with IWI for a quality period house, is that you can kiss your original fancy cornices/picture rails, skirtings and room proportions goodbye. EWI is going to be a challenge unless your home is in the small minority of detached houses that are rendered, with decent eaves overhangs and not listed.

Adding smart heating controls (Drayton Wiser in our case) to our bog standard gas central heating has made all the difference to us, as we now warm the whole house at a low level 24/7, with individual rooms heated as we need them on individual schedules. We're comfortable all of the time, and amazingly in three years we have yet to use any more gas than in the bad old days when we would delay turning on the heat in the Autumn and even turn it off during the day in the Winter and always at night. An additional bonus has been that I can heat my son's bedroom during the day when he's working from home, and can heat my mother's bedroom to what feels like an unhealthy level downstairs at night, so much better than floor zoning. In my case it was plug 'n play with no plumbing or electrickery required. If my mother hadn't been moved in with us, we'd use less gas since we could go a bit cooler on the rooms she uses.

 

[Stevers]

And the draughty old windows will be much less draughty and rattley (and just as beautiful) if you apply non-mutilating Stormguard 'V' strip self adhesive draught strip up each side and across the top like we have done to our previously draughty and rattley sash windows. It won't stop the condensation, but that's what Karcher Window Vacs were made for.

 

[mardinor]

Thermal lined curtains are as effective as double glazing. And draught proofing can be cheap.

 

[paulc]

Adding smart heating controls (Drayton Wiser in our case) to our bog standard gas central heating has made all the difference to us, as we now warm the whole house at a low level 24/7, with individual rooms heated as we need them on individual schedules.

Various pundits claim that you can save up to 15% by fitting a programmable thermostat (it doesn't need to be smart). I originally started using Home Assistant to control my ancient back boiler. It managed to produce around 10% saving, so the exercise was worth doing. For various reasons, I had to replace the old boiler a couple of years ago and took the opportunity to replumb the system and fit larger radiators. In the past, heating would only come on for an hour or two in the morning, and again at night. With the new boiler, it will fire up every two to three hours during the day/evening to keep the place warm. No real increase in gas consumption..
Still messing around with flow temperatures and PID gains, but I need a week or two of subzero temperatures to tweak settings a little further.

 

[MatthewC]

I have to ask whether there are there any damp issues with this house? Before considering any form of heating or internal insulation you need to prioritize and focus on any dampness. I am guessing that there are some issues and that is one reason for their bills being so high.

First, you need to look at the roof (tiles and leadwork), the rainwater goods (from the gutters to the drains) and have a look at the ground levels outside - is there ground up to the wall which is as high (or higher!) than the floor inside? This will cause the inner face of the wall to be damp - no amount of heat will adequately sort that as there is a permanent source of dampness. Thirteen years ago I removed over 100 tonnes of earth from around my house to eliminate that and it has really worked.

Then have a look at the windows and doors as a potential source of draughts and fix those. Also, think about insulation in the loft - I laid a sheepswool product in mine and it is great.

Only when you have addressed all this can you really assess the need for heating - personally I would regard UFH as incompatible with a period property anyway!

Matthew