JohnMo

Where does that come from (reference)? Why not use mineral wool, if it's a stud wall Frametherm 32 is pretty good, easy to install well. Polystyrene or PIR is a pain in the butt to install well.

You expansion tank, has a diaphragm in it, water side and air side. The Schrader valve is on the air side - t should be dry. As stated on Monday it is likely to be an issue with the expansion tank. Order new part, replace, done - or call your plumber to have him do it. But strictly speaking, as the expansion vessel is within the boiler casing, you should be having a gas safe plumber doing the job.

You should be able to run any heat pump via HA, just need a Shelly relay across the heat pump start up contacts. Then set your control in HA to open/close the relay as you require.

I have a 6kW heat pump that is run during the E7 mostly, for heating and hot water, split 6 hrs heating, 1 hr hot water. I say mostly as below about 2 degs I cannot get the number of kWh out the heat pump to satisfy the house over a 24hr period; in a 6 hr period. At 2 degs, I need around 60kWh. So at 2 and below the heat pump runs outside the cheap hours. It runs until it satisfies a thermostat in the hall, which is set to 20 degs (+/- 0.1 degs) So it will be worth looking at your heat pump choice (size) based on how you intend to run. I did run it a fixed number of hours, which was fine for a few cold days, but then the floor runs out of energy and you need to fully recharge it, while having a cold house for 24 hrs (it was -7 outside).

Sorry to be blunt Your idea is strange. Can't find anyone to install an electronic mixer, but expect someone to do this odd ball idea - no chance. Practically your idea is not even worth doing. Hot manifold run direct, no mixer, other manifold Ivar mixer. Once your boiler return temp drops below about 50 you are chasing points of a percentage gain in efficiency anyway.

Really just says the Samsung one you are comparing against is not that good (old design). The Vaillant one is slightly better than my R32 one at -2, mine is still at 3.22 (15% worse). Over the heating season, the number of days below zero are few compared to those above. Day to day or instantaneous CoP isn't that important, overall SCoP is. Then there is cost, the Arotherm Plus cost 3x more than mine and twice the Samsung one I expect, so a long pay back period. Bigger impact on CoP and SCoP is design and installation. That can make manufacturer numbers meaningless.

Is this what you are looking for? An expensive solution to make hot water. https://warmtepompboilershop.nl/product/auer-edel-eau-200l-warmtepompboiler-2/ Made by AUER France

Just looked at the specs for the Arotherm Plus, and it has a SCoP of 4.48 at 35 degrees, compared to my R32 ASHP its SCoP is 4.46. So overall nothing worth writing home about. It may produce better temperatures, but mine never needs to go above 55 degs anyway, so zero advantage to me. Horses for courses.

They exist in the domestic sense also. I did see a link on here for one. Took UFH return water, stripped away some heat, and added the water back into the system via close coupled tees. Think it was a french company making them. It had a CoP of around 4. But all the energy you strip from the water has to be added from elsewhere later. So didn't really see any advantage. Physics doesn't work like this, you don't get anything for nothing. What are you trying to achieve?

My advice was also flawed. However when you use UFH the floor temperature is increased. The water through the pipes could be up to 45 degs and the floor temperature will settle out at a higher temperature than the room. Well insulated it could be 2 to 4 degs warmer than the room. Other cases could be higher floor temperature. When using the calculation you need to take floor temp into account for downward heat loss, not the room temperature. So a room temp of 20 - ground 6 degs. 14dT. No under floor heating downward heat loss is room temp, ground temp difference against overall floor U values including carpets and underlay. With UFH Floor temp to ground difference. So very good insulation your temp may be 24 for a 20 deg room, so already 18% greater downward heat loss. The more insulation the floor covering provides the warmer the floor becomes as the heat has to overcome the upwards resistance before getting to the room. Flow temperature is a balance of upward and downward heat profile. So heat losses could be in 30 to 40 range compared to radiators if you are not careful.

Hello there - to clarify conducted and radiated heat moves in every direction - from hot towards cold For concrete the k-value depends on its bulk density and the moisture content in service. (CIBSE guide Table A3.1., 1980) Bulk density kg/m3 k- value W/m.K Internal (3% moisture by vol.) k- value W/m.K External (5% moisture by vol.) 2000 1.13 1.24 2200 1.45 1.60 2400 1.83 2.00 So assuming the 3% moisture and density of 2200 and 100mm thick concrete, your U value would be 0.1 / 1.45 = 0.069 1 / 0.069 = 14 = U value. So leaks heat like a sieve. So 18 times the heat loss you used. Re do your calculations and think again!

Must admit fully agree, now I'm using an UVC.

Was just a random number picked, but as you point out longer would be better. If you have a smart meter, half the jobs done already.

The way around that is to do similar to RED heat pumps, and use a modified version of the Harlequin vented cylinder (way bigger coils than standard), it also does not require an overhead tank, as the DHW is produced via a coil, so pretty similar to thermal store. No access to drains is needed, pipe to from heating coil, cold in hot out.

Or look at one of the Panasonic TVs (e.g. TX-65LZ2000B) ace sound quality no sound bar required.

I would just crack on. The only issue you will have, if at time of selling, the house you try to make out it's anymore than a shed. Call it a shed, no one will know or care if it's insulated.

Sorry your long post has just confused me. In short form what are you trying to do and why? Get the bit about a cascade system, adding additional heat. Are you trying to build a hybrid system or something else. Your system seems to want to rob pre heated add some more heat to use else where. Why not just heat it directly?

You can get strap on ultrasonic flow meters. Tape on and insulation around two PT100 probed and a simple data logger. But why bother just read the gas meter use over a 48 HR period, use the correct conversation factors convert to kWh. Get the weather data for the same time period. Log internal temp. Then subtract an allowance for DHW. Calculate kW per degree OAT. From there it's easy enough to get the heat pump size sorted out. No need to reinvent the wheel. You can do all that with off the shelf Shelly (and many others) bits.

We are just on 4G internet in the country with no issues

The only thing is, with sunken in electrical stuff, if it breaks (it will) you have holes in the wall the wrong size for replacements. Didn't think the reviews for sky glass were that brilliant? Do they tie you into having to have sky?

Mine certainly didn't operate on dT20, the circulation pump just modulates to get the dT the boiler controller wants to see. At flow temperatures of 40 to 50 the dT was the same as my heat pump - between 5 and 10.

Not cheap but wireless https://www.ebay.co.uk/itm/231266783709

I have a southeast array at 45 deg roof mounted and a vertical array bush split into 2 south east and nearly west. My generation profile looks like this. Late start is due to trees in the way and finish time is sun dropping below horizon (more trees). Not sure the faff of tracking is worth the hassle. In summer you are making loads of energy anyway. So I just optimise for winter.

Sunny day yesterday, 1/3 of electric came from the 45 deg array, the other 2/3 from the vertical.

So on a design day you can run the heat pump for 7 hrs and get a full 24hrs worth of energy into the floor.