Low pressure but where’s filling loop??

[SJB060685]

That pipe to right of the valve is 22mm and it's a gate valve, I'm presuming it's the cold fill to cylinder but it's hard to make out from the photos

 

[Siobhan]

Very strange and would be stranger again if the supply for that PRV was/is fed from one of the storage tanks and is acting like a NRV, unlikely but one never knows

I don’t think that PRV is fed from storage tank, don’t think there’s any water going through it, heat from the boiler seems to be rising up towards it but that’s all. This would be the normal expected function of it I guess?

 

[John.g]

Its relatively easy to check, with black valve open, adjust the pressure adjusting screw clockwise (directly opposite the black valve) and see if the pressure rises, if it does its mains fed, if not its from the tank and check your boiler again if it rises.
Are those two tanks the same Volume and is the level higher in one over the other.

 

[centralheatking]

Just to restart this thread apart from the fact your heating system shows 0.5 bar does it work ?
Are you getting Hot Water and CH ? when its gets long its best to refresh the issues as everbody can see whats going on and help more directly ...centralheatking

 

[Siobhan]

Well, curiosity got the better of me and I decided to try turning the black knob anyway, but it was already a bit loose and nothing happened when I heard it, theres no water flowing through it. This pipe is cold above the PRV and gets steadily hotter as it approaches the hot water tank. What about the pipe beside itwith the red “tap” on it (technical term?!) ? As it goes down it turns in the direction of the boiler downstairs.
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Thanks. System is cooling now and pressure has dropped to 0.2 again

Sorry guys, I’ve misled you here, it’s a bit of a maze but now I realise the pipe to the right with the gate valve is not going towards the boiler downstairs, it attaches to the cold water inlet of the shower pump. The narrower one on the left splits off into two pipes, one going into the hot water tank, the other splitting again into 2 pipes, one going to valves for upstairs and downstairs radiator and the other going downstairs in the direction of the boiler. Sorry for the confusion.

 

[John.g]

Just to restart this thread apart from the fact your heating system shows 0.5 bar does it work ?
Are you getting Hot Water and CH ? when its gets long its best to refresh the issues as everbody can see whats going on and help more directly ...centralheatking

Yes, was just thinking the same, what was the problem? but now it would be nice to know exactly where the boiler make up is originating.

 

[Siobhan]

Its relatively easy to check, with black valve open, adjust the pressure adjusting screw clockwise (directly opposite the black valve) and see if the pressure rises, if it does its mains fed, if not its from the tank and check your boiler again if it rises.
Are those two tanks the same Volume and is the level higher in one over the other.

I’ve done this now, adjusting the screw as you said but I can feel no water flowing through this pipe at all. The two tanks are exactly the same size they’re placed on a plywood board at same level and the water level looks the same too.

 

[John.g]

Very good then, I think that "proves" that the PRV is fed from a tank, and is wide open, last test, if you wish, just close the black valve fully and see what happens to the pressure(s) I think your boiler has a 10 litre E.vessel so would expect to see a rise/fall of ~ 0.5/0.7 bar between hot/cold if no expansion is passing back through the PRV. (maybe that's why the pipe was warm)

 

[Siobhan]

Just to restart this thread apart from the fact your heating system shows 0.5 bar does it work ?
Are you getting Hot Water and CH ? when its gets long its best to refresh the issues as everbody can see whats going on and help more directly ...centralheatking

Thanks for the tip. The initial problem is that while the boiler works, it’s not heating the rads well (it takes 2 hours to get the house to 19 degrees C in the morning). The boiler pressure doesn’t go above 0.5 with heating on, is usually at 0.1 with heating off. I’m afraid it’s going to drop further and cause the boiler to not turn on at all. Some rads get hotter than others but are usually all cold at the bottom. I possibly need to get the whole system bled to clean out the rads, and the control valves for the rads are broken so I can’t isolate upstairs/downstairs/HW, it’s all or nothing. So that’s on the list for after Christmas. But if I could just sort out the pressure maybe the house would be warmer! Thanks again everyone!

 

[John.g]

I presume you are talking about the boiler gauge pressure, if so, and if fed from a tank there should definitely be ~ 0.4 to 0.6 bar when cold, ideally you should have 1.0 bar (cold) to comfortably overcome the static head but you would have to feed that PRV from the mains to achieve this.

 

[Siobhan]

Very good then, I think that "proves" that the PRV is fed from a tank, and is wide open, last test, if you wish, just close the black valve fully and see what happens to the pressure(s) I think your boiler has a 10 litre E.vessel so would expect to see a rise/fall of ~ 0.5/0.7 bar between hot/cold if no expansion is passing back through the PRV. (maybe that's why the pipe was warm)

Sorry for my ignorance, to close the valve do I lock it clockwise or anti? The lower part of the pipe is now cooled quite a bit and the pressure gauge is at 0 (the gauge on the boiler is at nearly 0.2)

 

[John.g]

To close the water supply off you shut the black valve clockwise. To try and increase the pressure open the black valve anticlockwise and screw in the adjustment screw clockwise, the pressure will then increase if mains fed.

 

[centralheatking]

The tanks are identical but the one on the right Has a ball valve and seems to be fed by the mains, the one on the left has a pipe from overhead that drips into it - this pipe goes down behind the hot water storage tank in the hot press, maybe to downstairs where the boiler is but I can’t see.View attachment 41873View attachment 41874View attachment 41875View attachment 41873View attachment 41874View attachment 41875
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The PRV beside the hot press that’s showing almost zero pressure? Not sure what it’s doing there but the pressure rises slightly when the heating is on (the same as the pressure gauge on the boiler)

However I can’t see anything that looks like a swing or poppet valve near the cold water tanks - is that where I would find this?

This system seems a normal vented set up ..its a real puzzle ..chking
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This system seems a normal vented set up ..its a real puzzle ..chking

anyway we are off to North Cornwall for a few days soon , to stay in my last property there
before we buy my forever home in West Cork.then its hello Holyhead ferry terminal uck
..centralheatking

 

[Siobhan]

This system seems a normal vented set up ..its a real puzzle ..chking
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anyway we are off to North Cornwall for a few days soon , to stay in my last property there
before we buy my forever home in West Cork.then its hello Holyhead ferry terminal uck
..centralheatking

Sounds like a great plan, enjoy and thanks a million for all the help!
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To close the water supply off you shut the black valve clockwise. To try and increase the pressure open the black valve anticlockwise and screw in the adjustment screw clockwise, the pressure will then increase if mains fed.

Ok I’ve just done this now but nothing happened. It’s a mystery alright! Thanks so much for all the advice, even if the problem hasn’t been solved o e learned a ton and can now face a plumber with some idea of what they’re talking about!

 

[SJB060685]

To be honest what/however this system is configured it's going to baffle most

 

[John.g]

And the final pressures?

 

[Siobhan]

And the final pressures?

There was no change to the pressure when I adjusted the PRV - 0 when the boiler is off, nearly 0.5 when on for nearly an hour. Rte boiler gauge is 0.1 or 0.2 when off, nearly 0.5 when on.