JohnMo

We are lucky, we have a lower ambient in summer than down south, but our big windows drive solar gain and a need to cool. So when cooling we do get a great CoP, in winter a reverse situation can be true. That's a gshp. But sand 150mm down below surface and loads of trees preclude that, tried but gave up.

Why would you need that? This is my 3rd year of cooling, no dehumidification needed. None if you don't try too hard to go to low flow temperature. Almost all heat pumps do that. But your CoP is governed by lowest cooling flow demand temp for cooling and highest for heating. Higher cooling flow temperature give excellent running CoP. Over my 7 running hours yesterday I had an average CoP 7.8, using a massive 3kWh of energy, while removing 22kWh of heat from the house.

Don't take anything as gospel, you need to ask the right question several different ways to get a correct answer sometimes. First it's your house, choose floor coverings based on how you want the house to look and feel first, not because an algorithm says that's what you need. We chose large format ceramic tiles for looks, and being bullet proof, the oak floor, if required we can sand it back to restore the finish. Carpets in bedrooms because that's what my wife wanted.

Aren't you going down a rabbit hole of complexity for complex sake. Heat pumps like simple open flow systems, if you involve UFH you are limited to 14 to 16 Deg flow temp (depends on location), no dew point management specifically needed. Size any fan coils to operate at that flow temp. Otherwise your into electronic mixers etc.

The alternative to this if you're not going grant route, is to design the UFH to provide almost the whole house heat load, then have electric panel heaters in bedrooms, which only get switched on once in a while on very cold days if you feel you need to. Plenty on here have zero heat in bedrooms. Open bedroom door for an hour you bedrooms will be the same temperature as everywhere else. And make sure your heat pump does cooling, quite a few don't. Then you get the option to cool the floor. Simple wins for ASHP efficiency, cost of install reduces, direct DHW cylinder around £5-600 cheaper than a heat pump one, which buys loads of energy, especially on a time of use tariff.

It's all related to local temp and humidity, that's why I say a bit of trial and error. We ran ours at 14.5 target yesterday, it ran for around 7 hours, completely dry. Internal humidity stayed around 49% all day.

We just leave the MVHR to do its thing, windows open or closed. it only changing the air in a room every 3 hours. Not worth getting hung up on it. It's ventilation at the end of the day, not cooling.

I would tweek it down 0.5 degs at a time, leave for a while and check for condensation. You should be comfortable taking it down a couple of degrees. The lower running temp to will promote more heat uptake and a higher demand, so less cycling. It's a balancing act, so some trial error I am afraid.

Interesting email today, reference GivEnergy batteries only, if you're a member of Axle you get GivEnergy premium service included. You can invite GivEnergy users still, but no introduction bonus is payable any more - other makes of battery you still get the introduction bonus.

@Simon, beat me to it with the cylinder comments. For context on heat demand, NE Scotland total are 234m², with bed and living space at 192m² @-9 3.5kW. Not Passivhaus. So unless you are huge your heat loss calcs are way off.

They get your battery API, and control the export from it. Suppose it makes zero difference if it's energy direct from battery or PV. But you have to have a compatible battery to play and a smart meter

Next time you try to log in you will have go in via an email link. That link stays valid a few days only, repeat

Just shows why our grid pricing is completely screwed up! But I'm not going to turn away from a gift horse, while it's available.

I mentioned it before the weekend on another thread. Not far fetched. I used a referral and got £25, then on Friday an export earned £4.85 from Axel plus got paid by Octopus as well at 12p/kWh. They also state you will earn £10 per month. if you would like a referral code, just ask.

It's a bit like saying how much gas will I use. The log usage (cost) really depends on the house heat loss and how hard you need to burn. When we run our 6kW log burner, we run it at very low loads, one log at a time, so about 2 logs has burn time of 3 to 4 hrs, you may have a higher heat loss so run 3 to 4 logs and lots of air, so get through loads more than me. Cost also depends on how you source the logs. We have plenty of wood from cuts down down the build so zero cost, except my time. Way to many variables to give you a cost that is meaningful.

Nice trip hazard! If you need to it in the plant room, do you need to do it to every wet room, a fitting may leak while you out for the day? Do you have a floor drain? That maybe all you need. If not your hot swimming area will be difficult to empty anyway. Maybe over thinking it, our cylinder is above the kitchen, is it bunded area no, have I had leaks yes, were they an issue, no.

Wet rooms have tiles, main living space oak, bedrooms carpet (it's rubbish with UFH)

Explain? It close too which means what?

Are you all have open cladding, so you do get plenty of driven water in there? Otherwise a little OTT. I would be more interested to see how you are keeping wasps out, one small crack or warp they seem to get behind the cladding, then they start building nests.

And they are showing a 15kW heat pump. So unless you house is several 1000m² it's a bit large. Are you going for the grant or doing outside the grant? I have found very little difference in running costs doing DHW via immersion only. Which is outside the grant allowed method of heating. But direct immersion heating reduces install cost and cylinder cost. Heating design you have two options, but both options require a room by room heat loss calc, this allows sizing of room UFH array and radiator sizing. Option 1 is to run everything designed for the same flow temp. Then ideally run as a single zone. Option 2 run at different flow temperature. Then you may need zones, your smallest zone defines system volume. Which you need to add water volume to meet a 20L x min output kW if heat source. But a mixer driven by ASHP could have it's own WC curve so be operated as a single zone. No option above needs a LLH or buffer. Another option is to do fan coils in rooms upstairs and this gives you bedroom cooling (radiators don't), the UFH can do heat or cool anyway.

Just follow manufacturers instructions of chosen membrane. If you need additional belts and braces for airtightness, your primary airtightness measures need to be looked at.

If I was doing it I would do something like this with mineral wool. Easier to work with than PIR, use a breather membrane and you end up with all the ventilation drafts eliminated also.

Fix without them?

ASHP, all electric, but have a stove which gets used infrequently. Voltage moves about a fair bit, grid is currently 244V can be as high as 153V. Used to get a few short power cuts, but our battery now hides this.

Historic politicians came from a very small pool of the very rich and privileged. So not really a modern issue. Isn't that another issue itself?