JohnMo

I used a mix of copper and Hep2O from ASHP to house. Much easier to get hold of. Pert-al-pert for UFH is way easier to get where you need it.

See some recent threads on render staining from wood cladding. Build do what you are comfortable doing, get other to do the stuff you are not. I managed them one trade in, one out, to keep it all manageable. Ground work I got others in for that Walls I did myself (ICF) Roof got people in PV myself and electrician All plumping myself Floor insulation and UFH myself MVHR myself Roof insulation by others All none load bearing internal walls myself Plasterboard by others and all taping. Electric by others ASHP myself Project management myself Happy with the way I did it, wasn't too costly and was completed in a year.

Cascade system design should limit this to a large degree. Nothing wrong with opening windows with MVHR. There is a difference between breathable and airtight. Breathable normal means vapour open, so can be airtight also. How are you planning to line the internal walls?

Could you simply add more insulation in the low areas? Use EPS sheets to make up the difference - they are cheap enough.

To make it beneficial (running costs and heat losses) you need good airtightness, do you have a plan to tackle this? What do you mean by granular control? MVHR is pretty much switch on, commission, then forget (except filter clean/replace). Ours almost never goes into boost and is set at about 0.3 ACH. Titon, UK company, UK support, you actually get support from the designers not a call centre. For retrofit look at coander effect supply nozzles to simplify duct routing, also look at cascade MVHR.

If you type @ and immediately after start typing sav... you will get name appear below, select from the drop down and the saveasteading will be notified of your reply

We were very similar, and ICF, the assessor just used the ICF approved details for u value, cold bridging and junctions etc. Not sure why you think a different result will appear. They fill in boxes. We had a separate invoice to pay for sap but architect arranged everything.

You need the full assessment that compares your build with minimum building regs of your house. Isn't this something your architect sorts out? They have no care if it's an ICF or any other type of build.

Most of what you buy is 19mm for outdoors, although some of mine is 25mm. When flowing a 6kW ASHP will be flowing around 1m3/hr, you can pro rata that figure for different sizes of heat pump. At that flow rate the fluid velocity is moving through the pipe (28mm) at about 0.5m/s, so the exposure time to the outside world is very limited. So a 10m run of pipe the water is only exposed for 20 seconds.

Fit doesn't exist any more, you get paid per kWh of actual export. But I don't get paid, so haven't used anything for that. So standard tariff I used 25p E7 I used 14p and 30p

Mine don't - I just heat to 50, then I can have the shower as hot as I want. Or use you luxury setting (whatever that may be). 40 to 45 degs in house is just too cold for DHW. You set your DHW temp to suit your needs, not what someone else they set it to.

When comparing quotes look at or if not given freely, ask for Uw values for the windows. Many will give you Ug. Uw is the U value for the whole window including frame - to give a good indication of heat loss. Ug is just the glazing element - so is a bit camouflage for rubbish performance windows. Aluminium frames, unless very expensive, tend to have very poor Uw. When we were getting quotes for double glazed Best uPVC, was 1.4, worst 1.8, one company would not tells as they had never been asked for the Uw Aluminium tended to be nearer the 2 mark. Our wooden framed French doors are double glazed, with a Krypton fill gas they are 1.1.

That will be the case, our heating last year was off in April, this year in May, not back on again til late October. Once we go below an average of 10 degs (24 hr average) the house is starting to cool enough to prompt the heating going on. But we have cooling on as required via UFH system mid May to mid September. Our last couple of houses, the heating was never actually switched off, had known it to come on mid July on a colder than normal nights.

Just spent 30 mins calculating saving of PV (6.5kW), battery(13.5kWh) and E7 tariff and no PV or battery and standard tariff. Below is based on actual ASHP kWh used (metered) and long term monitoring on energy taken by the house (cooking, washing, borehole pump, sewage system, MVHR, lights, averages out at 17kWh/day) So during the heating season we are saving about £725, by allowing us to take a big proportion of the energy on a low tariff and some generated PV. During non heating season including running ASHP in cooling mode as required looking at a saving of £635, by making a better utilisation factor for PV and if required only taking in low tariff electric. So a total saving of £1360 per year. Equivalent to a 58% reduction in annual energy costs. For us and our spending on Battery and PV (self installed) its about 6 years pay back.

What was it mist coated with? We used Dulux trade throughout, including the mist coat (30% watered down) no issues. It looks like the emulsion hasn't adhered to the mist coat.

8 to 11kW is way over sized. Our heat loss is the same as yours and we have a 6kW and it's big. Don't underestimate what heating you will need, don't believe the hype that well insulated means no heating. 3kW over 24 hrs is still quite a bit of heating to do, 72 kWh a day, CoP of 3 that's still £6 a day. 7 deg day will be about half of that.

So a couple of wrong assumptions above. Condensing mode is nothing to do flow temperature is all about return temperature and only return temp. The ambient dew point is the flue gas dew point. Which approximately 53 degs for natural gas not sure about LPG. The condensing heat exchanger is there to preheat water, but also to condense the flue gas, this is where the efficiency uplift comes from. The condensing of the flue gas also latent energy to be transferred to the water. Now to burst your bubble, pre heating return water will stop or reduce the condensing effect and the efficiency gains you have made. The more steam visible the less likely you are condensing, the condensing is occurring as the flue gas hits the atmosphere, not where it's useful. Don't - see comments above Read the article it's a little simplistic so misses much of the details of what's really happening. Here is a better one to read https://www.heatgeek.com/condensing-boilers-efficiency/

Good spot Can't get that, as smart will not talk to outside world.

Isn't that just another building, so you see a roof of one building and wall from another?

Interesting - we are doomed Interesting, but how do you get hold of it and would your structural engineer and BC be happy?

Passivhaus trust say Within a single dwelling the air speed in the primary ducts should not exceed 2~3 m/s and in the final runs to room valves the speed should be limited to 1~2 m/s. So I assume for noise is one reason. But secondly to keep fan speed low. The higher the velocity the more the pressure drop, for a given flow rate, so the faster the fan has to run to compensate.

Its a difficult calculation really, if you can export and get paid for it, not sure the maths will ever make much sense. If you have PV and don't get paid for export but only have a G98 sizes array and home during the day, again not much sense as you can self consume reasonably easily. Once you get more PV or areaway all day self utilisation gets more difficult, so the battery allows you self utilise almost every you produce. They also allow you to use TOU tariffs. In even in Dec I was able to utilise 75% of off-peak priced electric.

I did toy with the idea also, but the maths makes little sense. They are a £1000 more than a direct immersion one - that's a lot of electricity. Plus you have a decent ASHP sitting ideal that can do the DHW easy enough on just as good CoP. Some are coated steel with anodes to change so be careful, the Edel units are stainless.

Would assume so, they will probably start the circulation pump so it doesn't stick themselves via the controller. So would switch off completely.

Where is the insulation going?