ProDave

So to ensure a silent night time, set the set back temperature to 5 degrees and accept if there is an off period in the middle of the day the house might get very cold. If you can't accept a very cold house in the middle of the day then make the morning heating time stay on for longer and make the afternoon heating time start earlier.

A couple of points. I think we determined that although @zoothorn unit is a split unit, it has the gas compressor in the outside unit, so all that i in the inside unit is a heat exchanger, water circulation pump, expansion vessel and some controls. Apart ftom the pump in there it should be no more noisy than my monoblock unit. +1 to the time settings being wrong. Before you next get Vailant out, write down on a bit of paper what times you want the heating on and what temperatures you want and ask them to set it to that. For instance my heating comes on at 6AM and stays on all day until 9PM with a set temperature of 20 degrees. Of course that does not mean it runs all day unless it is really cold, it will turn on and off as the room thermostat dictates but after 9PM will not come on even if the house goes cold. In your system you would achieve that by setting the temperature between your required times to 18 degrees or whatever you are comfortable with and setting the night temperature to say 14 degrees. If you want to ensure it NEVER comes on at night, even when it's damned cold, set the night time temperature to 5 degrees, but then you must accept after a really cold night it might take longer to heat the house in the morning. That is the price you pay for a silent night. Now hot water time settings. One feature of heat pumps is they usually only heat the rooms, OR hot water, never both at the same time. I have my hot water set to come on at 11AM and then stay on until 8PM It is not often anyone showers here in the morning but if they do there is enough hot water for one shower in the morning still in the tank. the not coming on until 11AM is to ensure maximum use of solar PV and we have some shading issues that mean much before 11AM generation is low due to the shading, Now your dilemma between wanting a warm house when you get up and wanting it silent at night, is it WILL need to come on before you get up. So you have to accept a time in the morning where you are prepared to accept the noise it makes to warm the house before you get up.

The basic "control" into the heat pump is heating on or heating off. That is the only "control input" that my ASHP has. From that you can derive any operating mode you want. I chose simple time control with a programmer and simple fixed temperature room thermostats. but you could instead have one or more programable room thermostats that would set different temperatures at different times of day. You seem stuck with people that do it their way and are not open to making changes so it suits what you want. Hence why I suggest you might try someone else. You would be surprised how many times I have to go and sort out the wiring of heating systems that are not operating as the customer wants because so many installers to be honest don't actually understand what they are doing.

And a mild climate.Mine has been on for a month.

Yes the only noise I hear from mine is the gentle hum of the water circulating pump. That is the same type of water circulating pump you would use with a gas or an oil boiler, so the noise would be the same regardless of what heating system you had, and is not a heat pump issue. It does not bother me asleep and it does not wake me up in the morning, but at night i prefer to go to sleep in a silent house without even that low level noise. My controls are simple. A normal type of central heating time clock to set what times the heating and hot water functions are on (can be set to different times) and a room thermostat in each room. If you wanted to profile it for different temperatures in different rooms at different times of day or night, you would simply have a programmable thermostat or just a master programmable thermostat instead of the time clock. I suspect the issue here is you got a basic install by a team of fitters that just do basic installs. If tou want better more versatile controls perhaps you are going to have to pay someone better to change things?

It's all done with a conventional central heating type programmer. It comes on at 6AM to ensure it's warmed up by the time we typically get up about 8AM

It goes off at 9PM and comes back on at 6AM

Are you saying the issue is the joists are sagging mid span? Or they are not level at the ends? Or both?

If a Hep20 one fits, that's what @pocster wants to use isn't it?

To stop condensation forming and dropping onto a ceiling below. Up here at least, the incoming mains cold water can be VERY cold in winter.

And I will bet a standard tap connector will be too fat to go down the tube hence it will need the special one that should have come with the kit.

Nail hit on the head. Just pester those installers until they come back and fix it.

Okay, another try. With that end off, screw the "end" onto the tap. How much tap thread sticks out the other end? Is there enough thread to get a tap connector on? And if so will a tap connector fit down inside the tube?

Mine is 5kW and all under floor heating.

So your "shroud" screws onto the tap and will seal (with ptfe tape?) What do you see looking into the bottom end of the shroud then? What is the function of that grub screw I see? Is that at the top end or the bottom end? I am still not convinced this is going to look right? It is still going to be a deck filler mounted onto a couple of poles. you should have bought a proper floor standing tap, e.g.

Do let us know how you get on. With say a 200L UVC, you fill the tank with water at say 50 degrees, then turn on the hot tap and you will get 50 degree hot water up to the point you have drawn all 200 litres out of the tank and it will then quickly go cold. Now fill your 200L thermal store to 50 degrees. Turn on the hot tap and you will get 50 degree hot water. but by the time you have drawn say 100L from the hot tap you will have removed half the stored energy from the tank, so the water that is left in the tank will be a lot less than 50 degrees now and so the hot water temperature will be lower. So you either need a very much larger thermal store, or you need to store the water at a much hotter temperature with a thermal store. They usually have a thermal mixing valve to regulate the delivered water temperature. As Heat pumps don't do much over 50 degree hot water, the results with a thermal store are likely to be disappointing.

Perhaps it's time just to bite the bullet and pay a different, competent plumber to come and sort the niggles if you are convinced the supplier can help no more and are not prepared to fight with them?

This is a garden room. What's wrong with raising it another 100mm to get more insulation under the floor?

Are the 2 rooms in the garden room completely separate? I would be tempted to fit one of the cheap air conditioner units that can be bought for not a lot over £500. They are a small air to air heat pump that can do heating and cooling. I believe you can for not much more buy them with two inside fan units so one for each room. I would keep garden room and house heating separate.

Yes just call the installers back. Don't even mention Vailant replaced part of the HP. That will not have cause the loss of pressure and dribbling tundish issues.

How should I know, I was not there? If you don't know, nobody does.

In hindsight, in such an exposed position, an outward opening door would have been a better choice, more likely to be intrinsically waterproof.

I am struggling to understand what actually happened here. You had a new heating system installed or so you say, with new radiators, new pipes, a new hot water tank and a new air source heat pump. It has NEVER been quite right, the noise issue and this losing pressure issue(s) So get the INSTALLER back to fix it. What is difficult about that?

Well SOMEBODY installed it. That SOMEBODY needs to come back and fix it. We can't help you determine who that was. A clue might be who signed the commissioning paperwork for the unvented cylinder? But it is hardly the fault of Vailant that the blow off valves are passing water. They didn't make or fit those did they?

Take a picture of the shroud offered up to the bottom of the tap, and a picture of the bottom end of the shroud If the shroud has a female thread that screws onto the bottom of the tap, then there is no way you can connect another pipe to the tap and run it up the inside.