JohnW

Thanks @PeterW We've specified a dedicated air feed for the stove in our plans, so hopefully it won't impact the MVHR

Thanks @dpmiller, I'm aware that the stove needs to be room sealed and have it's own air feed - the model we're currently looking at is the Stovax View 8HB.

Thanks @Alphonsox, good to know someone else has been through the same dilemma and has come out the other side. Economy 7 heating, an idea I hadn't thought of - I used to live in a house in Portsmouth years ago with the old economy 7 storage heaters and I thought I'd seen the last of them!! Have you installed an ASHP at your build? If so, I would be very interested in having a chat about your experience and maybe even get a referral for someone who could give me an install-price that I could live with. PV is very much on the long-finger.

Thanks @Nickfromwales Yes, Holy ? indeed, that's exactly what I said when I saw the quote! I suspect the builder asked their usual plumber to price it and I don't think they are familiar with ASHPs as almost all houses in the area are Oil. Therefore and I'm guessing here, but I think the price was inflated to cover all eventualities to the point were it was too expensive for us. We like a fire in the living room, hence the stove and if we're having a stove we thought it might as well heat the water while it's at it. It will be a room sealed stove with it's own external air supply. It sounds like the back-boiler complicates the plumbing somewhat, hmmmm . It'll be a hard sell to my better half to try to remove the back-boiler. Unfortunately I don't have any quotes or designs, we had originally spec-ed ASHP and when the first price for the build came back we had to find areas for reduction, so we changed to Oil and were shocked at the reduction of £11.5k but it was also very welcome - double edged sword. Would you have any designs you could share for a similar setup to the one you mentioned above, i.e. ASHP/HP UVC/Buffer tank & DHW pre-heat etc...? No great love of cooking with gas, the only reason I'm entertaining LPG is because I assume it would be cheaper to convert from it to mains gas when available.

Thanks @ProDavewe have a as-designed SAP report, but unfortunately it is based on our spec before it was trimmed due to budget. The SAP report was based on a 200mm cavity, 140mm inner skin (u-value 0.15) & ASHP, these have been reduced to 150mm cavity, 100mm inner skin (u-value 0.19) & Oil fired boiler, so I'm not sure it still applies. We didn't size the ASHP, that was up to the builder/plumber, but I suspect it was deliberately priced very high, because they are not familiar with the setup and would prefer to install what they are used to installing, i.e. Oil. Yes, mains gas will definitely arrive but you make a very valid point about cost of connection. The gas company will prioritise higher populated areas and therefore I suspect it might be 4 or 5 years before they are coming passed our site which is on the outskirts of town. Therefore it would be very expensive to get them to track to our site before the other areas. Calor Gas are currently offering either a "free" boiler or £500 towards the boiler of our choice, which would involve a 24moth tie-in period. This has made me consider LPG as an option as I was hoping mains gas would be available by the end of the 24months. Thanks for the pointer about no combi boiler if we're using PV - this is the sort of thing I need to know, thank you.

Hi All We're at the stage where we need to make a final decision about our Heating & Hot water system and we would really appreciate some advice. We're building a 230 sq metre, 2 storey house (GF 120, FF 110) in Co. Down, Northern Ireland... Family of 2 adults, 2 teenage boys (long showers, most days) Work/school means the house is unoccupied for a large part of the day Block built full-fill 150mm cavity walls Triple glazed windows throughout Mechanical ventilation with heat recovery Underfloor heating on the ground floor and radiators on the first floor Multi-fuel, back boiler stove Airtightness target of 1 m3/(m2 h) We will have a south facing pitched roof which is crying out for solar panels, but with no RHI in NI both solar thermal & photovoltaic are expensive options. My preference is PV panels and I plan to put all the wiring in place during the build and then at some point in the future add the panels. Mains gas is on it's way to us but won't be available until at least 2 years after we finish the build. I'm working on the assumption that mains gas is the best option and therefore we should put something temporary in place and then switch to mains gas when it is available. We've ruled out Air Source Heat Pump due to cost (we saved £11.5k when we removed it from our spec and replaced it with Oil). I would really appreciate some guidance as my head is pickled thinking of each option and permutation. My specific questions are; With a reasonably airtight/insulated house we hopefully won't need too much energy. Therefore am I over-thinking the whole issue? (In which case Oil is probably the way we'll go) Whichever fuel we decide on, what's the best way to use the energy provided by PV panels on those few days it actually is sunny in NI? We've been advised to let intelligent heating controls (Dataterm IHC) run the UFH, but as the house will be unoccupied for long periods is this not wasteful? Anything else I should consider? Thanks in advance

Hi, I'm hoping for some help & advice from others in Northern Ireland. Having saved for many years we're hoping to complete our build without a mortgage (so no lender involved). We also plan to live in the house for the rest of our days (so no intention to sell). We're using a local Main contractor who is not linked to NHBC and they have asked me if NHBC will be involved to sign-off the house at the end. I would appreciate hearing others opinions on whether it would be a good idea to spend circa £2k for NHBC cover (or not) and whether there are other better alternatives? Thanks J

Cheers @Declan52, might just do that and save myself £1,300, thanks.

Thanks @Nickfromwales, it's easy for a duck-out-of-water to forget that

Thank you very much for all the very constructive replies. You have all convinced me that PIV has it's place in older/leaky houses and that by installing it in a new build (without trickle vents) I am doing the wrong thing. My build is by main contractor and the cost I've been given to install & commission MVHR is around £5k, so it's a significant potential saving. BPC have given me a price £2,500 for parts and £1,450 to install & commission which brings it down to £4k (if the builder is happy for me to organise the MVHR separately). Thanks again for all the help.

Hi, Due to budget constraints we've removed MVHR from our build and the Architect has suggested a cheaper alternative, Nuaire Positive ventilation unit. I'd never heard of this approach to ventilation. Have any of you had experience with positive ventilation? J

@Declan52, my thoughts exactly - thanks.

Thanks @Declan52, we're in the fantastic position that we're hoping we won't need a mortgage...that's why I was wondering if there's any good reason to have the architect involved if we don't need them to write letters to release funds.

Thanks @NIreland & @Declan52 they are asking for £200+VAT/week for the duration of the build, which is a lot of money! In my view, there are parts of the build that need that money more than the architect.

Ok - we've received our tenders, reduced our spec and received our revised tenders and I'm delighted to report that the bottom 3 prices are within 1% of each other. Either they are all colluding or we can be pretty confident that the prices are fair (hope it's the 2nd one!) So now that we can choose a builder, someone has suggested that we need to employ our architect during the build to sign-off the build at certain points. Apart from sign-off for mortgage purposes, can any of you give me any good reasons why I should employ our architect DURING the build?

Hi @Ryan85, it's a block build, 200mm fully filled cavity, 2 story house total floor area about 230 sq metres. Thanks for the heads-up on the PIR prices, it seems ALL materials are going up in price. Gives me a feeling that the sooner I get started, the better.

I'm planning to use a Main Contractor and am about to go out to tender. I'll be asking for an elemental breakdown of costs so I can hopefully compare quotes. Have any of you got a good example of an elemental breakdown that you could share with me? Thanks.

Really sorry to hear about your latest set-back Ian. Hopefully some day in the not too distant future you'll look back on this with a sense of satisfaction, saying "I got through that!".

Fair point, we're going from block to block, they probably won't work for brick to wood. They do an "L tie" which might work.

We're going with a 200mm cavity and have been recommended Teplo type 325mm long ties, but you're right...expensive compared to ordinary ties.

Thanks @oranjeboom, good to know someone else is using this approach. What thickness is your thermoblock?

Thanks @craig

Thanks @Vijay, that looks interesting. Someone else suggested a similar approach using a different product Foamglas. Have any of you heard or used it?

Thanks @MikeSharp01, I assume Building Control are happy with this approach?

Thanks @Declan52, it's a big slider 2400mm tall by 5635mm wide.