JohnMo

If no additional pumps that can be deleted. I just have summer winter switch - that's it and leave it to get on with it. A good analogy. Our does get warmer than that at peak solar gain, but still has that cathedral feel, all the heat being suck away from you. A better option may be ceiling cooling - same as UFH but in the ceiling. Most GSHP aren't reversible, but can act as a passive (ish) heat dump. So complexity comes making them act in reverse

That is hows ours ended up. Some self levelling compound and a grinder to a could high spots. I also had the option to have the whole polished with 2 guys staying overnight. If I was doing a polished floor, I think I would get it done before any internal walls went in. But as the wife hates it, I had no option so a simple paddle float it was.

@SimonD this isn't a criticism of what you wrote, more a criticism of industry in general. And a less than pragmatic approach to cooling. Think the issue when you speak to big manufacturers, is they see a flow temp of a set goal, it really doesn't need to be. So complex isn't really needed. But it's difficult to set practical expectations and sell something. It has to do x or it fails. So manufacturer fall into the camp of you can have cooling, but we do not recommend you use it. I can understand some complexity with a gshp if you want to actively cool below ground temp. But you can cool with gshp at ground temperature plus a bit for losses through the heat exchanger. So effectively have the heat pump off and circulate ambient water and use ground as a heat dump. Actively charge ground with excess heat from the house. Not sure you need anything else, other than a heating system for that. Our first year in the house, mid summer the water in floor was at 24 degs. Our house just stayed too warm all the time. Anything that allows circulation to remove floor to a heat dump is good, a bog standard GSHP will do that. An ASHP with cooling will do that. ASHP you just run everything above dew point. The two temperatures proposed here by the OP, is just complexity for the sake of it. You set a single flow temp and let the ASHP manage it based on return temperature or you add a thermostat for cooling and let that call the heat pump into action (£50 or less has that sorted). Your fan coils will have a temp sensor that modulates fan speed, so if room is to hot or cool, fan speed will correct that. UFH as long as the floor surface temperature is below 20 it will actively pull heat from the rooms. Flow temp set point depends on depth of modulation and cycling, a well sized heat pump that will run hours on end, you set flow to about 14 to 16, a heat pump that is oversized will cycle and run about 20 mins you can actually set to about 12 degs. You don't even need a weather comp curve as it gets in the way due to dew point. The above is not Aircon, but makes for a more comfortable house, it cools quicker at night if you suffer from solar gain, which is the whole point. Manufacturers just see cooling as Aircon and the barriers go up. Which isn't helpful or practical. My advise if people want Aircon buy Aircon and live with the constant drying of the air and a draft 24/7. If you want a more comfortable house in the summer, switch your floor to cooling, it isn't perfect but costs nothing to implement and if you have PV nothing to run.

If at night you can turn down the MVHR aren't you actually running too high in general. There should be zero reason to change base rate at different times of the day. Get a simple co2 monitor and move about at different times of the day. And actually look at what is occurring and tune the flow based on actual needs. I am using Ubbink duct, no noise. You have either under installed ducts based on your flow rates or you are flowing to high a rate.

Double post

A concrete base and a building on top, sounds less than temporary. My house is on a concrete base it ain't temporary. The planning permission will state clearly if PD rights are removed or they stay in place. The OP just needs to read the planning permission documents.

I would have as last on my list of things to improve. A kvs of 8 means it will flow 8m³h of water with a 1bar pressure drop. A kvs of 10 will leave the valve hydraulically invisible at heating flow rates even with glycol (you don't have). 8 is near enough.

Pipe roughness is about 0.0004k (mm) for multilayer. Copper new is about 0.00015 so smoother. By the time it's covered in deposits that could be 0.03. Your clutching at straws going down that route.

No - no affect on ultimate flow rates through system just energy usage.

Isn't that because while developing a site under planing permission, there are no PD rights, you are legally bound to develop site to the agreed plans, without deviation. That would be my understanding also

Why do you need any electric cables in the roof? Put them in the wall and do wall lights also. Leave the whole roof area open as you want it. You need to think about how your insulation is attached to roof (fixing method) and plenty of other details so trades don't mess up.

The issue with volumiser plumbed as is, (if I have understood correctly) during DHW heating cycle, you are also having to heat an extra 100L of water every DHW heat cycle. You ideally have the volumiser in the central heating return only and tee in the DHW cylinder return after the volumiser.

They obviously don't want the work - move on to the next company

I would really concentrate on how get to best heat transfer from pipes to floor. Do it wrong and system performance will be poor. An option is a biscuit mix. Poor heat transfer will require higher flow temperature for the same heat output to room. Not sure your proposal will be good enough, wood is a good insulation so heat transfer not the best. You also need zero air gaps around the pipes. Every air gap will diminish heat transfer opportunity. Get as much insulation in the floor as possible 140mm wood fibre should really be increased to 200mm+.

What the two circles, one must be your cylinder what is the other. How does the return piping from the heating interact with the two circles as you only have return pipe from the two circles?

So just about the same as @sharpener 28mm of copper.

Isn't the norm for motors 4x rated capacity? All the equipment you have listed I would be doing 25mm².

Have you done voltage drops calculation for expected loads? Sounds a bit small 10mm²

dT is your flow dT from the heat source and is a variable. The bigger the dT the higher the output flow temperature is for a given mean temperature (heating output at radiators or UFH), so ideal is to run a low dT. But you can run any dT you like within reason. But as suggested by Vaillant, flow is king with with a heat pump. You need to get rid of bottle necks. So you need to get rid of pressure drops where practical or add additional pumping power to the system to overcome them, such as a second pump on the return piping run, set at a fixed speed to get full system flow where you need it to be.

That's your issue your flow temperature is way to high for current outside temps and a new build house. Your floor output will be huge, your thermostat is controlling nothing else. Now the counter intuitive bit. You need to dial back the temperature, on your curve. This will allow a slower more measured heat input and allow more time for the radiators to back fill any missing room temperature. Low and slow will allow heat to be absorbed the building. Allow system to run without any setbacks or off periods. Your WC should look something like this for the UFH 15 OAT flow 25 and -3 OAT flow 35. This will allow the majority of the heat for the house to come from the floor and your radiators just ticking over. If the house is getting to warm dial back the -3 flow temp 0.5 of a degrees every 24 to 48 hrs. If you do the above you can leave the UFH flow meters fully open and leave the ASHP to control flow and dT.

You need to calculate the pressure drop of the whole system. 1 bit of it's a bit meaningless without seeing the whole picture. Have a look here for some guidance https://heatpumps.co.uk/technical/pressure-drops-flow-rates/

Just sounds like you need a little balancing done If your UFH is getting to temp and radiators not, your curve for the UFH is too aggressive assuming you are mixing via an electronic mixer. If no mixer, slow the flow rates to each loop in the UFH so it outputs less. Knock 0.5l/m off each loop. Less radiators as they are. What flow temperature do you have set are you running weather compensation or fixed flow temperature?

Piping size isn't the only thing affects pressure drop, ball valve strainers can kill flow, I took my strainer cage out and added a full flow filter instead, good improvement in flow, I also replaced 3 port valve for a high kvs one again more flow. Poor selection of anything in the circuit will kill flow. 11kPa is nothing of a pressure drop, so you are loosing head somewhere else. 11kPa is around 1m head loss. Not sure what size pump you have but it should be 6 to 8m head pump. I have a flow rate of around 1320L/h for a 6kW heat pump. So things to look at Valves fitted need to be full bore Diverter valves look at a kvs of over 10 UFH ensure all flow meters are fully open Radiators look at how the lock shields are set and balanced Ball valve strainer, install a proper filter with low pressure drop instead.

@Gus Potter The other simple way to run the UFH is again all open system and if thick screed is a simple low hysterisis thermostat or via ASHP controller if it has a built-in thermostat. Set thermostat to 20.5 to 21 and ASHP to fixed flow temp of 32 to 36. And then let the thermostat run the system. With UFH and a new build those flow temps will give great cycle times and run once per day most of the time. Pretty good CoP. Run time will vary with outside temperature. Then you also have room to oversize the heat pump easily, without causing to many issues just incase we get the -20 degs.

But they have to be sized correctly to do that. True You can, but after loosing internet (signal from source - not house internet issue) for quite a few hours the other day, I wouldn't let anything internet based anywhere near the heating system. In most of the UK if you never allow house to overheat, you run at about 13 degs without any condensation issues.