JohnMo

That would heat my house at -9 outside. Even poorly insulated a 1 to 1.5kW through wall ticking away would be good. It would only take 300W electric. Or about 7-8p an hour to run

Why bother with a split system, just get a through wall Aircon unit. They are generally smaller.

Buy Greenwood CV2 or CV3 dMEV. They are best part of silent, they have smart auto boost on rising humidity levels (so taking a shower for example) and cost pennies a year to run. Then install humidity activated trickle vents in place of the your manual ones. Any trickle vents in wet rooms seal up. Then you will have a simple demand activated ventilation system.

Good possiblity is no. If you have intermittent fans currently I would consider changing to dMEV, these run continuously at a low level and are silent. In our last house the utility fan didn't come on for the 10 years we were there.

I would leave it alone for a couple of hours and see if it fixes itself. Are you running weather compensation? But some alarm bells You have ASHP which is great, but your house is zoned and this will mean inefficient running If you need thermostats flow temp is too high. If you have zone it may also mean you have a buffer again driving inefficiency.

Not got the money at the moment, to change car, so a bit of a sacrifice to save a hundred quid or so.

You won't need much sun to make it super hot. Add blinds/curtains to room lights, window and bifold, and manage temperature by closing as needed. If you an ASHP can it do cooling?

Video to watch Thread to read

So where is that mentioned?

as I said you need to read building regs, have assumed you are in England. Not sure where your figures align with what BR asks for? From building regs Mechanical ventilation with heat recovery Ventilation rates 1.67 For dwellings using mechanical ventilation with heat recovery, each habitable room should have mechanical supply ventilation. The total supply air flow should be distributed proportionately to the volume of each habitable room. 1.68 Mechanical supply terminals should be located and directed to avoid draughts. 1.69 The minimum total continuous rate of mechanical ventilation with heat recovery is the whole dwelling ventilation rate in Table 1.3 1.70 For dwellings using mechanical ventilation with heat recovery, each wet room should have a minimum continuous mechanical extract ventilation high rate as given in Table 1.2. Tables are

Without fully check AI answers, I wouldn't trust them at all. The answers just change depending how you ask. Go to the core document - building regs - what does that say? Understand BR, it makes life way easier, no one can pull the wool over your eyes. I could read it for you - but...

Have you looked at coanda effect supply terminals? They look like this and move air across the ceiling about 4 to 5m, before coming down. Maybe easier than floor ducts.

Save £1000+ and buy a humidifier? When you look at Aircon, some will monitor the humidity and draw in fresh air to manage RH%.

Do you actually need a feed in the dining area, does your dining area have a door to elsewhere in the house? Or a vertical wall connected to an accessible area in the existing house?

How? from reading up on it, it doesn't do it it's a heat exchanger in the air stream. Just AI says yes, doesn't make it real. Download the manual and have a read. If I am wrong I will happily eat my words. I did look at an evaporator unit (different make) for the MVHR you need very dry incoming air for it being if any use. UK humidity made as good as useless. That's how it works needs cold water through a heat exchanger to cool the air.

Datasheet extract -

We have exactly the same overheating issue. Prime reason for finding a reasonably price ASHP, and cool via the floor. According to data sheet at a water flow temperature of 7 degs, and 400m³ h you get 1.5kW cooling - pretty much a waste of time in my opinion. Not sure it does evaporation cooling according to reading the data sheet, it needs cooled water.

But I would add, have it only on the heating side of the 3 port diverter valve. Otherwise when heating DHW you are also heating an unnecessary high volume of water. Plus if you have UFH pushing 50+ degs water directly into the floor once the 3 port diverter swings back to heating duty - not good.

Really depends what was asked for? Easy access to top of grass they work. Plant some shrubs to either side would soften the look, not really seeing an issue?

Are you paying the utility bills for a rental?

My cylinder was in a summer sale so several hundred off normal price (currently selling at £1200) Heat pump was on eBay a distributor selling excess stock normal price around £4500, I paid £1300 after some bargaining. I got no warranty, but was willing to take the risk, it was still in the manufacturers box unopened. My labour is free.

If the quoted unit is capable of 600m³ and it's being asked to sub 400m³ at boost I see zero issues. I would expect to drop to level 1 (220m³) once the house has dried out - unless there are 10 people living in the house. Also get a humidity sensor, in winter you don't want to drop below about 40% RH.

Because building regs tell you too. It's also based on number of people that could be living there. Passivhaus have a figure for single bedroom and a different one for double rooms. Wet rooms have have there own figures. BR sort of do the same.

For building regs compliance you need a given volume flow, this is calculated differently in England and Scotland. So go to the relevant page in the building regs. But passivhaus work on approx 0.3ACH. The issue with a big house (you have a big house) is over ventilation and the house air getting very dry in winter. Ventilation is nothing to do with bedroom volume - it's all about how much CO2 and humidity is being generated. Two people in a big or small room generate the same amount of each. They have include volume and the ventilation mode is cascade. Cascade is a pretty standard way of ventilation. So imagine air being pumped in to a bedroom and being extracted via bathroom, the hall is being ventilated via cascade.

If it's solar PV you heat via the immersion, using a diverter. Wouldn't bother with solar thermal these days, it's an expensive one trick pony. But if you are getting an MCS solar PV then just export excess and get paid for it. If a self install divert to hot water via immersion. Either way a 2 coil cylinder is for solar thermal. It also takes away a chuck of cylinder volume dedicated to solar thermal.