New build heating options

carvillshill

Apologies in advance if this has been well covered but a search hasn't answered my specific questions.
We are in the middle of a new build large (almost 5,000 sqft) house (4 kids already and a possible mother-in-law residing) and the issue of heating is now occupying us.
We are building a very well insulated dwelling (300mm cavity between two 4" block layers, cavity filled with insulation. Triple glazing throughout, almost passive standard)
Our architect is the project manager and is steering us towards underfloor heating and a geothermal system. Having had initial reservations about underfloor based on poor experiences with it some years ago I think I'm persuaded that the more modern systems are fairly reliable. I am however a bit nervous of the geothermal sytem. It would seem to make us very electricity dependent and I worry that if we return to the days of electricity strikes etc this might be an issue. I also wonder about the cost benefit ratio compared to other sytems, most importantly oil. The archi thinks oil is overkill given what is likely to be the small enough heating requirement of the building.
I would welcome general comments on poster's experiences of geothermal versus other heating systems for similar builds to ours in terms of cost to install and run and adjustability/comfort.
I should mention that we have plenty of space so do have the option of a horizontal system and that 'er indoors has her heart set on a stove in the kitchen/diner which is unlikely to feed into a back boiler.

MicktheMan

First off, 5k sqft is massive even with mil in residence:)

Anyway, you ought to have a phpp analysis done first before going any further and let the result drive your decisions re heating technology.

Have you had a prelim BER analysis done / how will you comply with Part L?

If your architect thinks that oil is overkill then perhaps underfloor with geothermal is, imo, also overkill if the phpp analysis show a close to passive level for heat load / demand.

Also, make sure your energy advisor understands and explains the effect that thermal mass, airtightness and ventilation has on heating bills and comfort.

fclauson

I agree with Mick - get a hop done - I went UFH and a/s HP

read all my other posts any beliefs you had previously go out the window - the house sits at a constant temp and hence oil is not the best solution

Ufh is the way to go plus an inset stove to sit around on a winters night

BarneyMc

carvillshill wrote: »

The archi thinks oil is overkill given what is likely to be the small enough heating requirement of the building.
I would welcome general comments on poster's experiences of geothermal versus other heating systems for similar builds to ours in terms of cost to install and run and adjustability/comfort.

I would have thought geothermal as overkill compared with an oil boiler (at least at initial capital cost)?

fclauson

BarneyMc wrote: »

I would have thought geothermal as overkill compared with an oil boiler (at least at initial capital cost)?

from a cost point of view maybe - but you have to meet Part L somehow !!

Also make sure you HP is correctly sized - mine is a 8Kw HP - 6 of which is the immersion - which has been on 2hrs since Oct 12 !! (which was me turning it on to test it)

I was originally quoted a 17Kw pump which I think would have meant I could have fried eggs on the floor it would have been so warm

currently at 0deg C I push 28deg water into the floor (the HP has a heat curve based on outside air temp)

A "normal" 2008 house would have needed 40plus into the floor

Tommyboy08

carvillshill wrote: »

Having had initial reservations about underfloor based on poor experiences with it some years ago I think I'm persuaded that the more modern systems are fairly reliable. I am however a bit nervous of the geothermal sytem. It would seem to make us very electricity dependent and I worry that if we return to the days of electricity strikes etc this might be an issue. I also wonder about the cost benefit ratio compared to other sytems, most importantly oil.

Don't kid yourself that the modern systems are more advanced, heat pump and ufh technology haven't changed much in the last ten years, the bad installers and bad practices are what have changed, well theirs still more bad ones than good ones but do some research and you'll find one, oschner and heliotherm are the better options,
As for your worries about electricity strikes, I've never seen an oil or gas boiler or a circulating pump working in a power cut ;-)