JohnMo

I've use pipe in pipe, but not on anything domestic. Marine diesels use pipe in pipe if the pipe, should it leak, would allow fuel or lubricant on the turbo charger or exhaust system. Don't really see any reason to waste your money in a domestic situation for water.

Couldn't agree more. Our bedroom UFH is poor performing compared to the rest of the house. Good job we have the bedrooms cooler anyway.

Think you should tell the brickies about the new invention called a trowel. By the looks of they just throw their cement from about 6 foot away and call it a job done. No insulation?

Sad but true

I am afraid that's what the general public think and need a is simple Tag to associate low running cost houses with. Passivhaus - what's that, very small group of people have heard of them and understand them, most no clue, if they have heard of them they're airtight and must be stuffy and mouldy. That was the feedback I had from people I spoke to when I was building our near Passivhaus. Building education is very low in this country, with the general public and building professionals. Picking up on another thread, Tado sell smart thermostats to rest of the world, they degrade them for this country to on/off thermostats

Sounds a lot of money not convinced, didn't see anything on efficiency. Small A2A for heat and cooling?

Give it a go

Likely the loops or the piping leading to and from the boiler are full of air. How did you connect the UFH to the rest of the system? Do you have auto vent valves. Commissioning is the task of getting the air out the system, and setting pump speed, flow rates for each loop and setting flow temp. I have 7 loops, 3 approx 100m, the rest less than that. Pump is a Grunfoss of some sort, it came with the mixer.

Mine is 70mm logs, but will be insulated also.

Just to throw it in there ours is 6m wide and 4m deep. In the roof, fully insulated. It houses gas boiler big buffer and MVHR unit, but mostly full of stuff used as as store. Also have a fully insulated water shed, with all the borehole electrics, filters etc, 2.4m X 1.2m, this will soon house the ASHP expansion vessel, manifold and some electrics.

Daft question has the system been commissioned and flow rates set. If not it could be as basic as the flow meters are closed to min setting. Otherwise - Air in system the main issue when you have low flow, your boiler pump and the UFH pump should have enough power to move the water about. My manifold has a pump on speed 1 and is pulling and returning water without issue from the first floor, without assistance from pump on the boiler as well. Assume you had a plumber? If so get him back and tell him to fix it.

EcoAIR LC ECOWATT - dMEV

I am going to use a demand based dMEV fan. PIR or humidity will run it and then a timer will shut it off, all other times it will be off.

You are thinking too much. The inverter produces a higher voltage and I think frequency than the grid coming in to the home, so PV generation is used before anything the grid is offering - basically the grid doesn't come in to the home, because its voltage is too low. If you don't consume the PV generated electric, the electricity takes the next path of least resistance to the grid. You either get some money for the export or you don't. Capping the electric export via software within the invertor, just plays with voltage so it can't escape to grid. If you are using more than you generate, the voltage form PV falls and main electric comes in to your home.

and nail guns

Each loop is a single length of pipe, buried in concrete, once installed and covered in concrete very little to go wrong. During the concrete pour the pipe will be pressurised with air or water, so not likely to get damaged. Manifold is just a series of flow meter and either a manual or actuated valve for each loop - all pretty simple stuff. Much more likely to put a screw through a pipe hidden in a wall than a pipe under 50 plus mm of concrete.

I got the same on a new build also

They should be taking outside air in via a dedicated inlet. Also the stove needs to take all air from this duct, some don't

Not sure where you are getting your electric or gas from, gas is 10p and electric 34p. With a Heat pump and a CoP of 3, that's around £5 a day not £24.

If it's going via a grant, the heat loss calculation does not take any credit for MVHR, as it just takes the room air changes from a table within locked cells on the spreadsheet. My heat loss is about the same as yours. Have run the house for about 15 months and the heat losses and water usage is close to calculations. So I am about to install a 6kW ASHP. Key is to check at the lowest likely temp you have enough output to heat the house and out some heat into DHW.

Hope you have the floor well insulated, otherwise heating could cost you more instead of less. Just to throw another spanner in the works.

A pressurised should allow to charge directly without going through a coil, which is way better than a vented one. You may be better doing the heating direct from from ASHP, if you don't have lots of small zones you can do it without a buffer in most cases, so would just need some basic pluming a 3 way diverter valve. That way you get a better CoP. So on the radiators do your thermostats ever get to set temperature? If so they are big enough and could be argued you could reduce the flow temp.

No, the condensing occurs within the boiler at the heat exchanger, steam is converted to water (latent heat is captured), condensate drains out of the condensation pipe to drain. Mostly to do with dew point at the exit of the flue, steam get absorbed quickly by the air Your controller or screen on the boiler should show return temps, as you say look at your manual. Basically reduce the your boiler flow temp will directly affect your return temp. Normally a bit of a balancing act. Remember it's not the flow temp it's only the return temp you need to manage. The lower the flow the better the boiler efficiency. My return is about 30 degrees or below due to UFH, boiler efficiency in the region of 115% for heating.

It depends on how they are plumbed in in and the length. If they are coming off a large header pipe and the runs are short it may not be an issue. Is it a vented or pressurised thermal store? Do you have any other inputs the the TS, such as wood burner?

Couple of issues The steam being ejected from your flue indicate your boiler is NOT condensing so your boiler return temp is too high for efficiency. Some fine tuning of the flow temps would improve condensing of the boiler and way less steam being emitted from flue. Ideally you need a water return temperature of less than 54 degrees Second you need to be gas safe to install or modify the flue, so a job for the plumber.