ASHP settings help please?

[MrG]

Hi there all,

 

I am new to this site so please point me in the right direction if i am barking up the wrong tree! For about a full year i have had an 8.5kw Ecodan ASHP running for my bungalow. I have a separate 300L tank and all the control and internal components reside in my attic. For reasons only really explained by a long night in my local pub, I cannot get the help of the original installer. I have phoned Mitsubishi and they have said that for their service contract (around 265 per year Ish), that they can come and service the unit itself but cannot help with the non-Mitsubishi plumbing and configuration. So, here we are, with a unit that keeps either L9 faulting or simply appears to be working but no heat is generated in the radiators! The way I have been struggling on for some time is to visit my loft (daily now) and when the control is trying to pump around the system, gently push the diverter valve to release the main ASHP primary circuit into the radiator circuit. This all works fine until the radiator circuit shuts off due to being up to temp, or the water DHW heat circuit cuts in. Regardless, each time the diverter needs to release the water heated by the ASHP, it doesn't. This happened within about 2 months of the new install, and as my installer was still communicating at the time, he sent someone to check it out. and i assumed he replaced it. I now believe he did the same as i now do daily! Anyways, fast forward to now and I have read so much, that I am nearly there I believe but need your help. These Honeywell diverter valves were new when installed, but I am guessing that the rad circuit one may well be defective but want to check that the settings on the rest of the system are correct first and that I have not missed something really important. All the research I have done cannot find any more answers.

The Milo Piko pump, that pumps heated water from the ASHP up into the bungalow attic, is set on underfloor heating setting on the small house symbol.

The Milo Piko pump for the radiator system, is on the radiator setting, set now just above small house setting (I have 7 large radiators all on one floor)

I have a pressure release valve (the yellow thing. I think this is to circulate water back to the ASHP if there is no other open option?). I think that is roughly what it is called. It is set to 2. Nowhere could I find out what the correct setting is.

I have 20psi (1.5bar) on the radiator circuit pressure dial and I have checked the expansion tank for this circuit, and it reads 19.5. I assume this is okay?

I have tested my mains water pressure, and it is around 63psi (4.3 bar). The pressure in its expansion tank is 50psi. Do I need to pump this up to match that? Also the Commercial 315iPRV is set to exactly this mains pressure. Is that correct. This is for the DHW for the main pressure hot water.

Mitsubishi told me to that they would advice running on constant 45 rad temp rather than compensation curve for some reason. This was on the phone a while back. It was better but has not solved the issue.

If I know that these are all pretty standard settings, I think I can get on with simply asking a plumber to change the Diverter Valve for the rad circuit. Unless anyone can advise what I need to do to test further? I have no air in the rads btw.

Thanks for taking the time to read this amateur waffle and any help much appreciated. I have attached a few images. Apologies for the blurry rad pump but you can see where the dial is.

 

[ProDave]

If you have fallen out with your original installer, probably the best thing you can do is seek out a local to you heating engineer, or dare I say an electrian that understands heating system would be the best person.

 

It is a question of first understanding how the system is plumbed and wired and then methodically going through everything to make sure the right demands are in place and the correct motorised valves actually open and pumps pump when they should.

 

Remote diagnostics on a forum I fear are not going to resolve much.

 

And someone that knows the Ecodan heat pumps care to enlighten us what an L9 fault means please.

 

P.S I don't rate your original installer very highly.  He has never heard of pipe insulation up in a cold loft.

[MrG]

Thanks ProDave.

 

I don't rate him either tbf- have the lagging and doing it myself. L9 is a flow sensor fault so ties in with pressure or a faulty valve i should think. Thanks again.

[Beelbeebub]

You could use a multimeter to check if the control signal to the radiator valve is going live or not, and then if the valve is moving when it gets that live signal. 

 

What you described sounds like a dodgy valve actuator and/or valve. 

 

Regarding your expansion vessel, I assume you mean the one for your hot water tank. The pressure on that should be set when the mains are shut off and the pressure in the water system is relieved. The "at rest" pressure can be calculated by your plumber. 

[MrG]

Thanks all 🙂

 

[IGP]

Local Heat Geek rated tradesman?

https://www.heatgeek.com/find-a-heat-geek/

[JamesPa]

Given that you can fix the problem by manually operating the diverter valve, you appear to have isolated it, and it doesn't sound at all ashp specific.  Surely any plumber should be able to diagnose and fix