ProDave

That's not the way the regs work. Under 5kW you don't need to provide an air vent but above you do. It is certainly a wise thing to provide regardless. And I always understood the air vent should equal the area of the flue pipe.

Yes, imagine the terminals on the meter are labeled 1,2,3,4 then swap 1 and 4 and swap 2 and 3 Turn off AC isolator DC isolator and solar PV MCB at consumer unit first.

Yes if it shows a solid red light when generating, not a flashing red light, and still has not counted up, then it is wired backwards.

I have never encountered one like that. Why would you want to control the return temperature? usually you set the flow temperature and the return will be a bit lower.

When you took the picture, was the red light on the meter on all the time, or was it flashing and you just happened to get the picture when it was on? and is it still reading zero?

When you looked "earlier" was it very much earlier? Before the sun gets high enough to start generation, the Etoday figure will still be showing what it generated yesterday. On a dull day in winter it can be quite late before it starts generating, and you can even get really dismal days when it generates nothing in winter. As soon as it starts generating Etoday will reset to 0 and start counting up. From this I deduce you have had a very dull day today, but yesterday was much brighter.

Just a thought: If anyone wants to build a garden office on wheels then I might shortly have a very old tired caravan for sale that would make a good chassis to rebuild something new onto.

You can't even see them from Lands End, so where were you? On the stomach pump?

Short version: Another member had a free ASHP heating system fitted for free by some grant scheme and it has failed to work properly, failing to heat his old cottage to a sensible temperature. The manufacturers and installer have failed to resolve the issue and the forum has been trying to understand why it does not work. Ongoing..........

now you have done it @PeterStarck

So, Pro's: System installed for free, and assuming it works, it saves you having to fix the cylinder so saving £1500 Con's: The running cost WILL be higher by perhaps 1/4? So on that rough basis, how much is a 1/4 of a years heating bill? and how many years of paying that higher cost would it take to cover the £1500 repair bill if you were to stick with gas? Also, would you still be using gas e.g for an oven or hob? If so if those were the only thing using gas, the standing charge for the gas might be a significant fraction of the bill and you might want to swap those to electric and scrap the gas supply?

If you are going to do that, them make sure you get a written comitment that the system supplied will maintain a specified internal temperature in the house under all weather conditions with a comitment to upgrade it if it does not. You would not be the first to get a "free" system installed and then find it wanting for performance. so you have raved about your Octopus tarif but are switching to Ovo instead?

It's "return flow" that confused me. It's the flow temperature that is usually of interest and the one that is controlled. Return temperature is what it is and may be of interest to note, but it is not the one usually controlled.

What is wrong with a 5 year old tank that it needs replacing? As much as I like ASHP's I would not be swapping in this case. I would fix (assuming it is faulty) the boiler or replace it. You will not get cheaper heating than mains gas and an ASHP WILL cost more to run.

but the installer or Vailant engineers should have checked all that. So various engineers have visited multiple times and none has got it so it will heat the house properly. I think it is time for a different tack. This was installed by a grant scheme who then sent an installer to fit a system. It does not work as expected and it appears the installers have washed their hands of it, after all, they have been paid. I think what is needed now is forget the installers or the manufacturers, go higher up the chain. Go the the company / organisation that you first dealt with. They are the people your "contract" is with. Tell them that the system that they organised to be installed is not fit for purpose, and you need it sorted out so it works. Point out that the installers or designers of the system appear not to have done the job properly because after multiple visits they have failed to make the system work properly. Point out that it is your opinion the grant money they provided has been miss spent paying an incompetent installer to install an inadequate system and then fail to make it work.

At the risk of sounding like a stuck gramophone record, if we had the result of the "only 1 radiator on" test we would know which of those it was.

I would say this is the bit that has been done wrong at the bottom joint from flue to stove hence the water is getting out of the flue.

It will be condensation running down the inside of the pipe. Get your installer back, one of the joints is not right.

Blimey, 8 months. I am going to submit mine shortly, looks like I will be lucky to see it much before the end of the year. I can see this holding up my completion. BUGGER.

But we agreed a free trade deal with the EU. There are no tariffs. Yes you will have to pay UK VAT but surely not EU VAT as well? So the only justifiable extra costs are some extra forms to fill in. So either we, the great British public have been lied to and we do not have a free trade deal with the EU? Or the company are using this as an excuse to make extra charges?

Okay @zoothorn Now you have the thermometers to put on the pipes, just get the Vailant man to visit and demonstrate to him that the radiators can barely get to 40 degrees, tell him that is not hot enough to heat the house, and you need it made so that the radiators can get to at least 50 degrees, preferable 55. Tell him that is the problem you need fixing.

I take it you told them not to bother? I am just ordering some Rationel windows and not heard anything as ridiculous as this.

Re flow temps. Mine is set to 39 degrees in heating mode. Lo and behold, after a short warm up period once it has got all the water in the heating circuit up to temperature is delivers water at 39 degrees. It modulates the speed of the compressor to vary the power it is delivering to maintain that temperature. Once the rooms get up to temperature each room shuts down, and when there is little left actually heating,the ASHP will shut down it's compressor completely, only occasionally starting up to keep the flow temperature at it's set point. DHW is a bit more complicated. I have my water tank setpoint set to 48 degrees. I also have set the maximum flow temperature to 55 degrees. If the tank is cool when the SHW comes on, the flow temperature typically runs7 or 8 degrees higher than the tank temperature with the return perhaps 5 degrees lower and they slowly ramp up as the tank heats up. Like I keep saying, your low temperatures might be because the unit is set up wrong or faulty, or it might be because it is overloaded (too many radiators) and can't keep up. That much mentioned 1 radiator test will give us a clue. Once we know the answer to that we can advise what to say to the installers to get them to put it right.

On a bay window (so only a small job) the builder just cut the end off every brick at the correct angle.

One last try. The "only 1 radiator on" test will tell you if the heat pump is actually capable of delivering really hot heating water. If it is not, then something is wrong with it which may just be a setting. If with only 1 radiator on it gets piping hot, then try 2, then try 3 etc. I am trying to determine if the problem is wrong settings, or the unit just can't deliver enough power for all the radiators together (because it is too small)