ASHP low pressure help pls

[Nickfromwales]

3 hours ago, canalsiderenovation said:

We had not noticed any issue with pressure dropping or leaking tundish til after then so maybe....

....they didn't top back up and run the system to bleed it after topping up the glycol....

 

That's what my money is on if this issue never previously existed, and has now 'gone away'. Will be interesting to hear you report back as it is best to now check it every other week and note any drop. Check it when the system is cold if you can, so the readings aren't of hot (expanded) and then cold (contracted back).

 

 

43 minutes ago, SimonD said:

Needless to say, I'd always test the safety valves. And it is actually a requirement of G3 servicing.

Amen.

[canalsiderenovation]

6 minutes ago, Nickfromwales said:

they didn't top back up and run the system to bleed it after topping up the glycol....

 

I don't think they topped up the glycol, this is on their quote to do with the expansion tanks. They noted the glycol was low.... they are doing it on Friday.

 

The system will be cold (we have not turned the ASHP hot water on since yesterday and won't be turning it on before they come Friday AM. The heating will be off at that time too.

[JohnMo]

A service is supposed to test stuff and then fix and replace items needed. A standard item is test glycol and top up as required. They are also supposed to clean the condenser (finned heat exchanger you fan blows through), clean the casing, inspect expansion vessel pre charge pressure and top up as needed. A cylinder that has got a defective expansion vessel should not be put back in service, as the expansion vessel is a safety item, and be an item to fix asap, as the home owner would no longer have hot water.

 

If you took your car for a service and it came back with a service invoice stating your oil and filter needed to be replaced, and you will need to book that in as it's additional cost, you would be well pissed. That is the service level you have just experienced with ASHP.

[sharpener]

6 hours ago, Beelbeebub said:

Upshot was, there wasn’t anything to "service" - you look at the valve, make sure nothing is blocking the pipework etc and there are no visible signs of leak/degradation. 

 

I have an OSO cylinder fed from a rainwater harvesting system and it suffered from low pressure which I thought was the crap Stuart-Turner pump. Turned out the inlet reduction valve spring had been corroded away by the acid rainwater and was providing no counterforce for the valve.

OSO could only sell me a complete valve block but a 3rd party dealer had a replacement Reliance cartridge which was a lot cheaper.

 

The next fault to come along was the pump, cracked plastic impeller shroud. S-T regard them as unmaintainable but I had the bits of a previous pump which had failed with a leaking shaft gland so was able to fix, no thanks to S-T.

 

Will buy DAB if it fails again, you can get replacement glands for them.

6 hours ago, Beelbeebub said:

 

I asked specifically about turning the knob to activate the valve and he said you could but there was always the risk it wouldn't seal back properly and you'd have a persistent drip, which would mean the valve would need replacing. 

 

Other house has an Ariston cylinder with ?their own valve group which has a mesh debris screeen in it, MIs say to check this annually and I do this though I have never found anything significant in it.

 

+1 for always giving the knobs a twist when I am up there and it is always reassuring to hear the water gurgle away proving the D2 pipe is not blocked with spiders.

[Nickfromwales]

24 minutes ago, JohnMo said:

A service is supposed to test stuff and then fix and replace items needed. A standard item is test glycol and top up as required. They are also supposed to clean the condenser (finned heat exchanger you fan blows through), clean the casing, inspect expansion vessel pre charge pressure and top up as needed. A cylinder that has got a defective expansion vessel should not be put back in service, as the expansion vessel is a safety item, and be an item to fix asap, as the home owner would no longer have hot water.

 

If you took your car for a service and it came back with a service invoice stating your oil and filter needed to be replaced, and you will need to book that in as it's additional cost, you would be well pissed. That is the service level you have just experienced with ASHP.

Yup. Shite service. 

[Nickfromwales]

56 minutes ago, canalsiderenovation said:

 

I don't think they topped up the glycol, this is on their quote to do with the expansion tanks. They noted the glycol was low.... they are doing it on Friday.

 

The system will be cold (we have not turned the ASHP hot water on since yesterday and won't be turning it on before they come Friday AM. The heating will be off at that time too.

Ok. Once the glycol has been topped up, ask them to pressurise when cold to exactly 1.5bar so you can use that as a benchmark to monitor by.

[Nickfromwales]

They’ll have to raise the red vessels, as that’s on fixed pipework, but the white ones are on flexible hoses so make sure that if they just bend the hoses instead of lifting them that the hoses aren’t kinked.

 

If you can ask them to raise the brackets for all the vessels, to accommodate the Tesla valves, then I’d do so to ensure as good job has been done as possible for the fee. 

[Beelbeebub]

I guess the problem with a prv test is a proper test is to stick the immersion on and boil the tank, but that isn't really safe or practical. 

 

The units we had fittednhad a knob on the top you turned and that would lift the valve, which isn't really a test of the system only to see if the valve would open. 

 

TBH fitting a burst disc would be the safest way but i've never seen one on a domestic system. 

 

They do need to get around to sorting the g3 regs so that a system only connected to a HP without any immersion can be treated as a vented cylinder since there is no possibility a HP can boil the tank.  That would make installs easier 

[JohnMo]

28 minutes ago, Beelbeebub said:

do need to get around to sorting the g3 regs so that a system only connected to a HP without any immersion can be treated as a vented cylinder

Absolutely out of date nonsense.

 

Just bought an ASHP that does 80 Deg flow temp, unassisted.

[JohnMo]

32 minutes ago, Beelbeebub said:

TBH fitting a burst disc would be the safest way but i've never seen one on a domestic system. 

Too many heat cycles to keep it reliable without regular replacement. Plus some numpy would see a hole in it, and replace with some random bit of metal from the shed.

[Beelbeebub]

10 minutes ago, JohnMo said:

Absolutely out of date nonsense.

 

Just bought an ASHP that does 80 Deg flow temp, unassisted.

Still not enough to boil a cylinder tho? 

 

And if someone fits a co2 HP capable of boiling a cylinder - then it's g3 as per usual. 

 

The exemption would only apply to HPs deemed unable to boil cylinders. Could even be a tick box in the spec where the manufacturer declares the HP unable to reach 95C in all fault conditions. 

[Beelbeebub]

9 minutes ago, JohnMo said:

Too many heat cycles to keep it reliable without regular replacement. Plus some numpy would see a hole in it, and replace with some random bit of metal from the shed.

Good point! The old "nail in the fuse box" fix. 

[JohnMo]

15 minutes ago, Beelbeebub said:

Still not enough to boil a cylinder tho? 

 

And if someone fits a co2 HP capable of boiling a cylinder - then it's g3 as per usual. 

 

The exemption would only apply to HPs deemed unable to boil cylinders. Could even be a tick box in the spec where the manufacturer declares the HP unable to reach 95C in all fault conditions. 

still don't agree, one rule for all appliances, then you don't someone deciding to fit an inline immersion or adding a gas boiler later and then blow their house up. If you want vented rules install a vented cylinder, if you want unvented then G3, simple.