JohnMo

GSHP slightly higher CoP, but may not have at the tale end of winter, if you have cooled the ground too much. Not always inverter driven, so may not modulate as much, so will need a buffer. Generally a big faff, with digging and slinky and filling, ASHP easy to install.

Couple of things going on. A cylinder with a coil is designed to have around 75 degree flow temp going into it. As you reduce the flow temp the heat exchanger coil cannot transfer the heat away very well. When you get a certain point in the heating cycle the boiler will trip on a high return temp. Then go in to short cycling. As you are seeing. Not efficient. You may use less gas by ramping up the flow temp to 75, your return should be around 55. The heat cycle should be quite quick.

My wife makes a broth soup full of lentils and pearl barley, that's all you need and a hose pipe. So come around for some soup, wait about six hours, all the biogas you will ever need.

You can get a batch mixer, it has an auger in it for mixing and pumping out. Seen that done. But takes an age, if you are DIY ok, but paying someone, big cheque book required

Only things I would say about the cylinder is it insulation is very thin, so make sure any heat loss is usable. If you intend heating the cylinder to use on the overnight electric the buffer would be better on the supply side of the system. Is your heating system pressurised, if so the cylinder will need to be pressurised also with the same protection.

Daft question, why would the UFH pipes be anywhere near where the walls are going to be?

Without a pump is really a non starter, we did a couple of small sections of wall between windows and took ages, we used buckets, there is lots of concrete in the walls. I would start looking for a different build method, if it was me.

No issue with a buffer on the return leg. If your using electric to do heating and not oil, but confused with this bit and relevance to oil and a buffer? Easier fix to balance the heating system so that all circuits are on and flow at the correct rate for the room heat transfer required. Then no buffer needed. Sounds like you have too many thermostats.

Sorry but dream on, your downwards heat loss makes, UFH less than efficient. Slightly oversized rads to run at a lower temperature would be more efficient, as the downwards heat loss is lower. Your boiler would operate in the same region as it would with UFH so it's efficiency would be the same. Bury the pipes in the wall they are gone. As you say it your choice, your money. But seems a lot of work for higher energy bills for ever more.

It's great getting all these prices, but where is the structural design. If the structural engineer says no your back to square one.

Is high end just something that's been given thought and isn't just the normal monopoly house, with the basic fitted kitchen and bathrooms. High end can mean nothing, it maybe just saying you spent loads on finishes, lights, floor, kitchen and bathrooms, doesn't mean it looks nice, functions well. In our pavilion (bungalow yesterday), we have a great kitchen and great bathrooms. We spend quite a bit of time on the design, then sourced the right quality at the right price. You don't have to spend a fortune to get a high end finish, but you can. If you entrust the buying and design to a third party you will pay a high price for you high end finish. As with all things self build, if you truly self build you are very much in the day to day driving seat, if you self build by getting a third party to do everything for you, you are a passenger who pays the fees.

Yes

This is why you have to balance the system, it doesn't know the temp

You can get bends and plenums which give you direction changes. Your boost only needs to be 25% above normal flow. Your normal flow is between 0.3-05 ACH. So work out you ventilated area of the house and divide by 2 to 3 to get your overall flow rate. The extract and supply should be equal and be at the rate you calculate. Put a manual boost switch in kitchen and outside bathrooms.

Keep an eye on room temps. So if the thermostats start controlling the temp the temp in that room is too high. If all or most room are controlled by the thermostats the flow temp is to high so reduce a degree or two at a time . If only one or two room are not getting to temp or are too hot, you need to increase flow at UFH loop flow meter at the UFH manifold or at the rad to make room warmer, reduce flow to make cooler.

Not sure, but they say at over 3m3/m2 leakage rate the benifit of MVHR is small. You have to consider the energy use to drive the MVHR unit compared to recovery of heat. If air is coming into the house in an uncontrolled manner, but at an acceptable rate for ventilation, you are just adding additional ventilation, which you have to pay electric for.

Seal loft hatch, ensure all windows are draft sealed, if they have trickle vents these would need to be sealed. No cat flap Seal all wall sockets and light switches Even with all that, it could still leak like a sieve, due to the gap left at behind the skirting

That's a good price, but the Trianco company has closed. Pity. I was looking at an inverter Dream heat pump. It connects to smart life app so I was going to build a simple control logic in to that.

If I remember correctly the flow rate for the UFH is just over 12l/s

If you heat load is that low I would suspect it would be off. The average heat demand is around 1.8 to 2.0kW for the months of the heating season.

I am sure MSC has a complains process, you have a look in to it. Read up on heat geek, lots of free info on how set things up, well worth an hour of your time.

I noticed cool energy do a package consists of ASHP plus an exhaust air heat pump cylinder. But if you have an oil or biomass, just use that with a UVC for DHW. I have a theoretical heat demand of 3.2kW. I am thinking of getting a 3kW heat pump just for my underfloor heating. No buffer. Just need to get around how to make the gas boiler fire up if and when I hit a shortfall from the ASHP. But it is big enough for most of the heating season, just not the extremes. I can also then use it for cooling in the summer. Electric demand is 0.7kWh, so would run on solar most the time.

It doesn't mean having the temperature the same 24/7, that's why all system have a set back. The set back reduces the flow temp and by default the room temperature, still doesn't need a thermostat. But as you say you need to work at to get it set to run correctly. UFH and rads is not an issue, as you balance the room flows to get the temp you want. Thermostats just get set a degree or so higher than the target room temperature.

If your heat pump was MSC installed the performance output sheet they gave you with quote is a guarantee of performance. If you are meeting the figures they gave you, you have recall for them to repair / replace at there cost. As a note You cannot operate weather compensation correctly with zones shut off and thermostats controlling temperature. Thermostats and trvs are there only to limit overshoot if for example the sun's out heating the room.

I really wouldn't start messing with any settings, as these should all be configured, you cannot just change one thing without messing most other settings. You need to know what you are doing, with the correct test kit. Things you need to check Extract ducts, may have a filter at the extract point. The nozzle just slides out of the ceiling if there is a filter it will be cone shaped. Remove and hoover out 6 monthly replace annually if installed. The main MVHR unit will have filters inside, inspect every 6 months hoover out and replace annually. Make sure there is no accumulation of water. If you have boost switches use these prior to a shower and during cooking. In trickle mode the extract nozzle will just about hold up two sheets of toilet paper