JohnMo

Just reread this. Not sure your expectations will match reality with wet UFH. So to throw a spanner in the works. Modern well insulated houses don't have warm floors with wet UFH, the UFH flow temps are just too low. You max flow temp is likely to sub 30 degs at the coldest outside temperature, and that doesn't give a warm floor. You won't have cold floors either, but the floor really will not be noticeable warm. Typically floor surface temps are 1 to 3 degs warmer than air temp depending on heat losses.

Your manifolds have the valves you need - the flow meters. Start with all flow meters on the manifolds fully open. Let the heat pump run for a day. If whole house is too hot, your flow temp is too high. If the odd room too high turn the loops in that room down a little. Reassess the next day, do some final tweaks. If the odd room is too cool, the flow temperature is too low. increase flow temp a degree. After a day reassess, some loops may need to be reduced. Now as your flow rate changes from the ASHP, the loops will pretty much self balance.

First your flow temp is too low, you need to increase a couple of degrees to around 14 +. 12 is below dew point. If house is still at 27 you need to flowing about 16, until house cools. Work out your dew points - plenty of tool online. Cooling via UFH is the same as heating low and slow. Suspect the noise is likely to be the floor complaining about you trying too hard and contracting.

What is your flow temperature, how are you operating, more info needed

I would have had it galvanised. You still could. It looks like paint was possibly simply painted after welding with little or no prep. It should have been blasted to Sa 2.5 spec and then painted. Depending on paint type most primers are an open film, so water gets below the paint surface and you get rust. An epoxy primer isn't so can be left in a primer state. For me (others will say otherwise) 1. Get them/it galvanized 2. Send to an industrial painter to be blasted and painted correctly.

It calculates kW as either a positive or negative dependant on heating or cooling. The kWh heat delivered scale is exactly the same as electric meter, it only adds it doesn't run backwards. So in cooling the kWh counter stays static Not exactly correct, it calculates kW then adds a time function to get kWh. Heat pump monitor software has a tick box in the settings to allow it to understand if you also do cooling and it runs an internal timer to distinguish between cooling and defrosting. Once timer elapsed it knows you are in cooling mode and attributes the correct CoP, SCoP values

It's the inverse of CoP, so if calculating CoP you just get a negative figure, exactly the same calculation. Take the negative away you get EER.

We did at one point very tightly control house temperature and it varied maybe 0.5 Deg. But depending on outside temp etc the way the house temperature actually felt changed, so sometimes you felt warm others cool (I'll put my jumper on). We have relaxed (simplified )that control and just use a room sensor to control everything, our WC curve is 26 to 28 degs, so almost flat. Thick screed (we have) is pretty slow to heat and cool down again. So what happens in our house, in heating season, the UFH generally ends up running at night and spends all day off, down to about freezing and then the heat pump runs for some time during the day also. Colder it gets the longer the run time. Room sensor thermostat set to same temperature 24/7 for heating with a 0.3 hysterisis. We get some undershoot while floor plays catch-up, but we are in bed then so that's fine.

Actuators - no need, then you don't need a buffer. Hitachi, are quite good, but you need additional widgets for cooling AC just do UFH cooling. Maybe find a new installer

If you set as 2x zones. One zone valve for upstairs controlled via a single simple thermostat. But not sure I would bother. Or accept the UFH upstairs output is low anyway with the more open centres on the pipes, just let it run with downstairs as a single zone, and accept the extra water capacity as insurance against short cycling. This would ultimately allow a lower flow temperature overall and better CoP. But you may find you minimum realistic flow temp in mild weather is actually warmer than you really need, in this case use the controller thermostat in a suitable location to act as heating permissions. In mild weather 7 to 10 degs, you find the heat pump only runs a few hours a day. So, one zone, use the main controller thermostat and almost flat WC curve.

Last year on our 6kW heat pump it cycled, depending on load, we averaged around 4 to 5 CoP over the day depending on a few factors doing cooling. This year with a 4kW it can run low and slow, our dT was about 2.5 degs. Yesterday's whole day CoP was 7.3 including standby time/energy. We only cool if there is solar gains, so we have plenty of PV also. So it free. It would almost always get clipped from PV also, if we weren't using it, so it really is free.

No I am saying heat via immersion. Plate loading as you say just adds complexity you don't need. CoP compared to energy input depends on quite a few variables. CoP isn't always a true measure of energy input as you have to heat pipes, local fabric and cylinder. But with a time of use tariff, what's the point of using the heat pump to heat the cylinder, leave it to concentrate on building heat and cool. Keep DHW simple. But if going down grant route DHW via immersion isn't an allowed option.

The correct terminology is EER for cooling and CoP for heating. In effect I actually get a negative CoP.

Set up to run long run for periods, this helps a lot. Plus our ambient outside helps.

Yes. Our soak aways are huge, compared to normal.

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.