Schoolboy

Looking longer term the three phase allows the installation of a 22kw vehicle charger (vs 7kw max on single phase). This reduces the time for a full car charge by two thirds. In a household of 2 or 3 cars which each take 10-12 hours to complete a full charge on single phase this may be quite a benefit.

Wow - the EASHP did the hot water as well - brilliant! As you say high insulation levels (and airtightness) is key.

Slightly off topic but you are absolutely right to question the need. Regarding PV, we have never seen such a variety of professional advice, ranging from 3kw to 14kw, battery & no battery, single & three phase. I think it comes down to a) what we believe is going to happen to the price of energy and b) how much we are going to use. If we end up with a house with four busy adults running two electric cars, a three phase system may be worth the investment. If it ends up being just me and the wife, we may have overcooked it!

That sounds well thought through and if next summer is anything like the past one could be a game changer. Do you have a system designer or have you done that yourself?

That sounds great! We’re there any downsides? Was the unit noisy? How were your electricity bills?

Yes - effectively you are combining the ASHP with the MVHR unit. One of our biggest concerns, therefore is noise. The supplier does provide details of how to soundproof the plant room (utility room) walls and floor.

Sorry - forgot tho say the upgrade is to three phase. Apparently that is cheap. Our electrician has been quoted 4 times that! You're right - it's a sensible precaution just to add the UFH pipework even if you dont connect it up & use it initially.

Absolutely right - we need to make sure we experience it before dismissing. The system efficiency is quoted as "efficiency varies between 300-1,200% depending on flow rates and environmental conditions." The only real way is to see for ourselves and ask those using it what their experience is in terms of real world efficiency.

Yes - it's a real gamble not having ANY underfloor, isn't it! If you are going for an ASHP anyway, then I guess you will just go for a more standard MVHR system (as opposed to the HPV which costs a lot more but does the heating and cooling as one unit). We are going to visit someone who has taken the gamble and installed the HPV system and apparently loves it, so I will report back! We are also thinking 12kw solar pv, but will need to pay the DNO £10k to upgrade .

Thanks Jack - I will check this out. There are examples of these units in the Build It Education House at Graven Hill and Potton show home, so hopefully they should have feedback in terms of cost.

Goodness - I was looking at these just the other day: such good looking doors. Have you had any further occasions of leaks or managed to stop the water ingress?

Cheers - I have a feeling there will be a few of those

Goodness 15w/m2 is low! We wont be quite at Passivehaus standard so this may not be the best route for us. Agree that all options have their downsides! You're right, the UFH is not so complicated plus heating from the ceiling does seem to go against the laws of physics!

I agree - the warmed air is a very different feel to a conventional heated home. I think the idea is that this would only work in a house with good air tightness. The central HPV unit contains the heating element, plus there are additional 'duct' heaters (if required) where the air enters the room. Bathrooms have heated towel rails. For hot water there is a separate tank.

We are looking to install an HPV system in our new build, timber frame property and just wondered if anyone had experience of such a system? On the face of it, by removing the need for an Air Source Heat Pump and underfloor heating, it seems to simplify the choice process, but we are keen to hear of any downsides / issues by going down this route.

Just waiting for a survey to confirm we have no bats...in our flat roof house :) Have done projects before but not a full build, so looking for help and advice.