ProDave

The overall flow temperature you are seeing is the result of the return temperature, the flow rate, and the power you are putting into it with the heater. I would wager if you valved off the "off" heater, you would see exactly the same figures as you are still putting in the same amount of heat.

Download the heat loss spreadsheet from this post, it proved very accurate for my build. I would be looking to improve floor insulation in your build. We have suspended wooden floors with UFH but wood or slate flooring throughout and that achieved a U value of I think it was 0.13 and works well with the UFH. Carpets will slow down heat delivery

1) What U values are you expecting to achieve for the walls, roof etc? your house is about 92 square metres. Ours is 150 square metres and has a heat demand of about 2.3Kw at -10 outside. What dis you use to calculate your heat loss? Why not UFH? Easy to design and build at construction stage, leaves all your walls free of clutter and runs at a lower temperature than radiators so more efficient for the ASHP. Typically out HP will spend an hour per day heating DHW, so your HP would need to provide the required heat in 23 hours to allow that. Heat pumps generally do heating or hot water, never both together, and most allow different flow temperatures from the HP for each. 2) heat loss through the roof is exactly the same calculation as the walls, you just have to work out the surface area of the sloping roof, which will be more than if you had put a flat roof on the building. 3) depends where you are. I calculated worst case heat loss for -10 outside and +20 inside. The cold spell a couple of weeks ago we got to -12 here and some parts to -16. You don't want average coldest unless you are prepared to be cold, or use another heat source (e.g. wood stove) when it gets really cold, which is why I designed for -10. the average is much higher than but a winter anticyclone and the cold can hang around a long time.

My point was I believe (correct me if I am wrong) you can only get the BUS grant is cooling is not enabled? When you dig into the exemptions and conditions, you could be forgiven for thinking the government want to make it appear they are promoting heat pumps, but then put in conditions that restrict the number of installs, and then at some future point they will say something like we had the policies but people did not take it up, so not our fault there are not enough.

Let them get built in. If they even notice and complain, apply retrospectively, and if refused fit some ON roof ones over the top to demonstrate what nonsense it is. During my planning, I only realised at the last minute that I needed PP for the ASHP so quickly added that at the last minute. All these sort of green updates should not be needing PP imho.

I find it absurd that they exclude heat pumps that "can be used for cooling" for being eligible for any grant. The objective is to get people to reduce fossil fuel usage. Someone with a gas boiler has the incentive "it might be very slightly cheaper to run if the install is perfect" but even with the grant it will cost you a big wad of £££. That is it. No wonder they are not queuing up. If they were offered a system that not only would cut your fossil fuel use, might be a bit cheaper to run, AND could cool your house in a heatwave, they might be a little more interested?

Is that a warm roof, or do you have insulation to go in first?

Yes picture of what you are trying to board onto. It does not matter if the last support of the PB is not right at the edge, it is not that bendy. One of our gable ends (closest we have to a hip) before the counter battens went on And after plasterboarding

Hot having seen all the floor plans, if you went got 5 bedrooms all en-suite, would there be any shower or toilet that was NOT accessed through a bedroom?

Just to avoid thread drift, if we want to discuss failed government projects, perhaps someone could start a separate thread for that.

I would say build for your expected occupancy and use, not resale value.

Remarkably yes. Now compare that with trying to procure a couple of ferries.

Pictures of this "door with no sill" would aid understanding of the situation.

The guys that did our driveway, heated the pitch in a metal watering can using a blowlamp, and poured it out of the spout of the can (no rose fitted to the can) You need a well insulated glove to hold the can. Probably a more accurate pour than a saucepan.

The noise will obviously be more if standing in the air flow, and of course you will be blown by cold air. It is a theoretical question really. The ASHP won't be on doing heating when you are trying to sit in your garden, and if it happens to come on to heat the hot water while we are in the garden, I go and turn it off, the hot water can wait.

Good news about the replacement and good service by SA. Hopefully the changes to the start up sequence mean they have learned from failures and it will be more reliable, but the only real solution to prevent failure of the PCM vessel is a stronger PCM vessel. Is there any kind of vent on the actual PCM containment vessel, something to vent pressure if by chance some of it did reach it's boiling point?

My first boat was a "Frolic 18" a boat only made in small numbers by a small boat builder in Poole. Searching for "Frolic 18" got some unexpected search results.

Where is the boundary? I would have thought the middle of the grass strip? If so build it you the wall is just your side of the middle. Or with agreement from the neighbour buils it exactly in the middle as a party wall.

Did the plumber make any changes to the plumbing like different or extra expansion vessels, pressure reducing valves, over pressure valves etc?

This bit requires some joined up thinking. For my house max overall energy would be limited to 6000kWh pa. To match that with solar PV would require probably 8kWp of solar PV. While I would have no objection to installing that much, the DNO may have other ideas. I already know for just 1W over the 3.68kW allowed by default, there would be a network upgrade charge, and there is no guarantee that they would even allow 8kWp of solar PV. So if that sort of requirement is going to become normal, then it also needs to become normal that DNO's will accept that much without punitive upgrade charges.

I thought stone chippings were used on mineral felt roofs as a way of protecting them from UV. Do modern roof coverings need that protection?

About 6 years.

The 2 pack vsarnish had some odd restrictions on application, something like each coat must be applied no more than an hour after the last coat otherwise you then had to wait 25 hours? We gave the underside 2 coats, then next day turned it the right way up and gave the top 3 coats. And spilled red wine does not bother it either.

I will have to look that up. It's a pair of contacts on the main ASHP not the controller, and you have to enable that with one of the DIP switches in the control board. Do you have the installation manual for the HP itself, it should be there, if not I can photograph the relevant pages of my manual.

I have a 5kW version of the same era with that same controller. I concluded very early on that the controller was the most illogical thing known to man and there was no way the average "man in the street" could program that and set heating schedules etc. So mine is controlled from the "room thermostat" input and that connects to the UFH controllers and a perfectly normal central heating time clock that everyone understands. So I don't even bother to set the time on mine, let alone anything else. So I honestly can't say if forgetting the time and mode is normal or not. The main thing for me is, do any parameters that you have customised remain after a power cycle? THAT would be a right royal PITA if they all needed resetting after a power cycle.