Heating an old building

jonnym00

Hello

I'm renovating a 3 bed house built in 1635. Its has rubble(stone) walls of around 2 foot thick, the floors are tiles, a thin skim of concrete then bare earth, which I hope to remove and put in limecrete (I can save that for another post). The windows are all shot and will be replaced but its will still be quite drafty and I would assume a low thermal quality. I'm trying to return the house to a state where its breathing again removing all the water proof paints and renders. There is no mains gas in the village.

Now for the good points, the front of the house faces south catching full sun, the upstairs are usually quite warm as there into the roof with low ceilings. There is a chimney at each end of the house where we hope to fit a wood fired boiler

The complications is we are going to be joining to the barn behind, requiring the 1959 extension which houses one bedroom and the small kitchen to be removed, this will about double the platform of the house, there is no deadline for this, it will happen as funds allow. This means that specifying an oil boiler to run the whole house and barn will be too big for just the house and damage it and be very inefficient, however the thought of running two boilers or replacing one for a large one later seems very wasteful. There is no access to the garden from the road and no where to keep the volume of wood required to heat the water and space heat. Just to complicate things further the electric in to the building is very small, I think 60amp, making electric heating a problem as well

What to do? I'm wondering about the viability of a thermal store and an oil fired boiler big enough to serve both the house and barns, but I'm unsure of the practically and economy of this.

Thanks for any thoughts on this.

Jon

Cardew

60 amps - approx. 15kW - is not sufficient to run a house with electric cooker, kettle, heating and hot water provision.

From what you have written, a heat pump would seem to be a good option.

An Air to Air heat pump will be considerably cheaper and more efficient - essentially provides warm air.

A normal Air Source Seat Pump provides hot water to radiators and a hot water tank.

jonnym00

I did have a quick conversation with a green energy consultant a while ago and a heat pump specialist.

We ruled out heat source pumps as the company spec'ed the heat pump to run off two bore holes into the aquifer (we have one already which is capped which may be viable), which would take 250,000 liters a day from one bore hole and return it to the other extracting the heat in between. The consultant agreed with his sums but indicated the cost of the electricity alone to run the pump would make it impractical.

He felt very strongly it was the wrong technology, due to the age of the property, no damp course and part of the building being under ground the damp would always necessitate a higher temperature than the heat source could economically provide.

I ruled out air source for the same reason, but haven't done any research into it. Is it the same premise?

I forgot to mention we also need water heating as well.
thanks

Jon

Cardew

jonnym00 wrote: »

I ruled out air source for the same reason, but haven't done any research into it. Is it the same premise?

I forgot to mention we also need water heating as well.
thanks

Jon

Both types of Air Source Heat pumps(ASHP) simply extract heat from the air outside the property(even if that air is below freezing 0C) and move it into the house.

The most basic version blows warm air through a grill. The more sophisticated version heats water for radiators and a hot water tank.

A number of factors vary the output of these ASHPs, mainly outside ambient temperature. The gain is called the COP(co-efficient of performance) and typically an input of 1kW will produce between 2kW and 4kW.

jonnym00

Great do you have any suggestions of models I can take a look at?

Is the thermal store general perceived as a good idea? I like the idea in the future of using solar and possibly a wood fired boiler of some kind. I was put off complete reliance on it as it was calculated I would need 11 tons of logs a year to run everything. It was an online calculater but it was enough to make my back ache at the thought of it.

I'm going to look into upgrading the electricity inlet, I've read that they might be able to upgrade to an 80 or even 100 amp with a minimum of fuss as the incoming cables might be overrated. That would help in general, but I still don't fancy electric heat system.

Thanks

Jon

Ectophile

If you actually need an 80A supply, your electricity bills could be frightening. 80A works out about £12/hour at standard rate.

Cardew

Ectophile wrote: »

If you actually need an 80A supply, your electricity bills could be frightening. 80A works out about £12/hour at standard rate.

You would only need 80 amps (say 20kW) when heating + kettle + oven + appliances were on at the same time.

FreeBear

jonnym00 wrote: »

I'm renovating a 3 bed house built in 1635. Its has rubble(stone) walls of around 2 foot thick, the floors are tiles, a thin skim of concrete then bare earth, which I hope to remove and put in limecrete (I can save that for another post). The windows are all shot and will be replaced but its will still be quite drafty and I would assume a low thermal quality.

What to do? I'm wondering about the viability of a thermal store and an oil fired boiler big enough to serve both the house and barns, but I'm unsure of the practically and economy of this.

Sounds like a fun project...

If the replacement windows are made to a good standard, there is no reason why they can not be thermally efficient and draught proof. With two foot thick walls, the number of areas for cold draughts to get in would be limited to around the door/window frames and under/through the roof - Nothing that can't be fixed without too much of a problem.

If you are stripping off old layers of paint, plaster, and OPC render and going back to the original stonework, I guess you'd then apply a coating of lime plaster/render. One of the modern insulating lime plasters will help to improve the thermal properties of the walls as well as cut out any (most) sources of draughts.

As for heating - I'd be tempted to use a combination of solar and oil along with a wood burner to supplement the primary system. Fit a water tank with multiple coils, and then you are not restricted to one source of heating for hot water.

Gloomendoom

Cardew wrote: »

You would only need 80 amps (say 20kW) when heating + kettle + oven + appliances were on at the same time.

Our house has a 60 amp supply and was previously all electric. Similar age and construction to the OP's.

zaax

This house should have an in door well, most probally were the scullery was and that would be your second source of water

jonnym00

Ectophile wrote: »

If you actually need an 80A supply, your electricity bills could be frightening. 80A works out about £12/hour at standard rate.

Yes the bills often make me swear loudly, I work from home and have quite abit of kit running all the time. But I'm only worried about running of juice when every things on when it spikes. I try not to run at 20kw all the time;). I think we have decided that we will only have the fuse upgraded if its a straight swap by the power network and then it would be free.

Yes the windows will be good quality but with houses like this airflow in the house is very important, so draft proofing is good for the heating bills but not great for the house.

I'm very interested in the insulated lime plaster, I hadn't heard of that. I'm not allowed to remove all the plaster as its listed but on some walls its already making its way onto the floor, so could be used.

I'm worried about an air source pump blowing the electric every time the compressor comes on again if the washing machine and cooker is on then that kicks in it could overload it. If the electrics get upgraded we could look again.

I'm currently leaning towards a thermal store with a backboiler woodburning stove or possibly a log gasfication boiler, then later solar (if they let me) for summer. I would like to move away from oil if possible. I'm a hippy at heart and it feels wrong.

In the short term a hotwater cylinder liked to a back boiler woodburner with back up manual immersion heater (to control when it comes on so it doesn't coincide with other high electric usage)for space heating one room and all hot water, with another wood burner in the other side of the house backed up with electric heating might work for the short term until the barn conversion has been completed. That way I don't have to spend alot getting it up and running and pay double when the house is complete. What do you think?

thanks

Jon