Low pressure but where’s filling loop??

[Siobhan]

Hi all and thanks so much in advance for any advice! My boiler’s pressure is below 0.5 but I can’t see where the filling loop might be. In the photo below I though perhaps I should attach one to what look like valves on the two identical pipes on the left, but these both carry hot water so I guess that’s not it. Excuse the beginner’s ignorance but I’m trying to get a grip on the basics here to maybe avoid having to pay for a plumber (if I can even get one) at this time of year! Also including photos of the hotvwater tank. Last 2 photos show the pipes leading into a pump for showers, don’t think this has anything to do with boiler pressure but including them just in case. Any advice would be much appreciated!

 

[centralheatking]

Hi all and thanks so much in advance for any advice! My boiler’s pressure is below 0.5 but I can’t see where the filling loop might be. In the photo below I though perhaps I should attach one to what look like valves on the two identical pipes on the left, but these both carry hot water so I guess that’s not it. Excuse the beginner’s ignorance but I’m trying to get a grip on the basics here to maybe avoid having to pay for a plumber (if I can even get one) at this time of year! Also including photos of the hotvwater tank. Last 2 photos show the pipes leading into a pump for showers, don’t think this has anything to do with boiler pressure but including them just in case. Any advice would be much appreciated!

Tell us what type and model of boiler and the set up. Then we will guide you to where and how to give your system a squirt. centralheatking

 

[Siobhan]

Tell us what type and model of boiler and the set up. Then we will guide you to where and how to give your system a squirt. centralheatking

Thanks for replying, it’s a Vokera Minute 35HE Gas boiler- does that help?
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Thanks for replying, it’s a Vokera Minute 35HE Gas boiler- does that help?

It’s a system boiler by the way with hot water storage tank upstairs in the hot press

 

[SJB060685]

I like all the compression fittings next to and above electrical components.

 

[Stigster]

I can't see a filling loop in any of those pictures I'm afraid. You are looking for something that most likely looks like this - https://www.wolseley.co.uk/wcsstore...roof-pdp-w/std.lang.all/12/91/171291_wpdp.jpg

 

[centralheatking]

I can't see a filling loop in any of those pictures I'm afraid. You are looking for something that most likely looks like this - https://www.wolseley.co.uk/wcsstore...roof-pdp-w/std.lang.all/12/91/171291_wpdp.jpg

I just checked your boiler it does not have an internal filling set up. So hopefully somewhere you will find
two x shut off valves a bit like washing machine isolators , even with a shiny silver flexy connector.
Now normally they are close together and under your boiler, but you might find them in a utility cupboard...sometimes and often the loop is missing or lost ...so look around for what Stigster has put up...and report back...we will get you there ...centralheatking

 

[Siobhan]

I can't see a filling loop in any of those pictures I'm afraid. You are looking for something that most likely looks like this - https://www.wolseley.co.uk/wcsstore...roof-pdp-w/std.lang.all/12/91/171291_wpdp.jpg

That’s what I thought, do you think that means I’ll have to get the plumber in?

 

[John.g]

Could it possibly be fed from a (the) tank in the attic with a NR valve, this would give the minimum required pressure of 0.5 bar if the boiler is on the ground floor, it should have its own dedicated tank for this but I think shortcuts (wrongly) are sometimes employed where it is taken from the cold water storage tank, if so then the NRV may be sticking.
It is often teed into the cylinder coil.

 

[SJB060685]

It's a system boiler and unvented cylinder Jong.G. shouldn't be any thanks in loft.

 

[Siobhan]

Thank you all so much for your comments, I’m learning a lot! I have searched everywhere but the attic without finding anything resembling a filling loop, but I’ll get up to the attic in a while (kids need feeding, multitasking here!) and will report back. This whole heating/plumbing system was installed about 10 years ago and has given countless problems, and every other plumber who’s visited has been bemused and unimpressed by the way the whole thing was set up - so I’m prepared for anything!

 

[Jamie Leask]

The thing is the flexi might mot be attached and you may have two isolation valves close to each other. Or one of them may be a dounle check valve which looks very similar. In other words the flexi might be hanging up waiting to to attach to the threaded ends of the two valves.

 

[centralheatking]

The thing is the flexi might mot be attached and you may have two isolation valves close to each other. Or one of them may be a dounle check valve which looks very similar. In other words the flexi might be hanging up waiting to to attach to the threaded ends of the two valves.

The flexi might not be in the house which is why people leave them attached so they dont get lost.
Water regulations permit the heating end of loops to remain attached when not in use.

 

[rpm]

Some people have found them behind the Cornflakes box before now, other have been found in different cupboards and locations and as said the silver braided flexi may not be on show anywhere.

 

[Siobhan]

Could it possibly be fed from a (the) tank in the attic with a NR valve, this would give the minimum required pressure of 0.5 bar if the boiler is on the ground floor, it should have its own dedicated tank for this but I think shortcuts (wrongly) are sometimes employed where it is taken from the cold water storage tank, if so then the NRV may be sticking.
It is often teed into the cylinder coil.

Thank you all for your comments. I suspect what John.g. says might be the case. I’ve searched high and low in kitchen and utility and nothing. There’s no sign of a filling loop but I can’t even see anything that I could connect a loop to if I went out and bought it. In the attic I have 2 cold water tanks and nothing resembling a valve either, wonder what a NR valve looks like in case I don’t know how to recognise it. even if I find it, would i be able to fix it? Thanks again!
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Thank you all for your comments. I suspect what John.g. says might be the case. I’ve searched high and low in kitchen and utility and nothing. There’s no sign of a filling loop but I can’t even see anything that I could connect a loop to if I went out and bought it. In the attic I have 2 cold water tanks and nothing resembling a valve either, wonder what a NR valve looks like in case I don’t know how to recognise it. even if I find it, would i be able to fix it? Thanks again!

Going back to the hot press, could this have something to do with it?

 

[centralheatking]

Thank you all for your comments. I suspect what John.g. says might be the case. I’ve searched high and low in kitchen and utility and nothing. There’s no sign of a filling loop but I can’t even see anything that I could connect a loop to if I went out and bought it. In the attic I have 2 cold water tanks and nothing resembling a valve either, wonder what a NR valve looks like in case I don’t know how to recognise it. even if I find it, would i be able to fix it? Thanks again!
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Going back to the hot press, could this have something to do with it?

This is strange, you have two active water tanks in your loft ! go take a picture immediately please
we could all be barking up the wrong tree here. centralheatking

 

[SJB060685]

This is strange, you have two active water tanks in your loft ! go take a picture immediately please
we could all be barking up the wrong tree here. centralheatking

Exactly CHking.

I looked at pictures again. Initially I thought it was an unvented cylinder but on closer inspection it looks like it is but an open vented system?

 

[Siobhan]

Hope these help clarify things!

 

[John.g]

What is the PRV for that's showing almost 0 pressure?.

It also seems strange to have a TPR valve in a vented cylinder.

If one of the tanks in the attic is much smaller than the othner then that would point to it being a Feed & expansion tank.
If so and a NR valve is fitted then it would be installed on a horizontal section of piping and will look like that attachment, If fitted vertically it will be a spring loaded poppet (and IMO should not be used).

 

[Siobhan]

What is the PRV for that's showing almost 0 pressure?.

It also seems strange to have a TPR valve in a vented cylinder.

If one of the tanks in the attic is much smaller than the othner then that would point to it being a Feed & expansion tank.
If so and a NR valve is fitted then it would be installed on a horizontal section of piping and will look like that attachment, If fitted vertically it will be a spring loaded poppet (and IMO should not be used).

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.
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What is the PRV for that's showing almost 0 pressure?.

It also seems strange to have a TPR valve in a vented cylinder.

If one of the tanks in the attic is much smaller than the othner then that would point to it being a Feed & expansion tank.
If so and a NR valve is fitted then it would be installed on a horizontal section of piping and will look like that attachment, If fitted vertically it will be a spring loaded poppet (and IMO should not be used).

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?

 

[John.g]

Maybe should have asked, has the boiler pressure always read 0.5 bar?.

Maybe that's your filling Loop?, you may have a vented hot water cylinder and a unvented heating system? there is a black knob (v/v) on the back of the PRV, you might just see if this is shut, if it is just crack it open a touch to increase the pressure HERE to a a max of 0.3 bar, if it is the filling loop then the boiler pressure will/should increase by the same amount and due to the static head should read ~ 0.8 bar. You may find that the PRV is set to give o,25bar or so here so that (black) valve will be permanently open and the red isolating valve above it is also open so you have a auto fill PRV, I would just check out the status of any isolating valve around this PRV before adjusting anything though.

 

[SJB060685]

This is a very strange setup if I'm honest. As John says see if that tops it up and I agree if that gauge were to read 0.2-0.3 bar then the boiler gauge should read more due to the head, roughly 0.5 more at the boiler if its 5 metres below that gauge.

 

[John.g]

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

 

[Siobhan]

The heating was just been on for nearly an hour and the pressure on the gauges has risen to approx 0.5, it’s slightly higher on the boiler gauge which is approx 3 metres below the hot press one, but there wouldn’t be anywhere near 0.5 difference between them. I was told the pressure should register somewhere between the pencil lines on the boiler gauge. Boiler is off now, should I go ahead and try to open the PRV to increase pressure a bit?

 

[SJB060685]

When pressurising a combi/system boiler you need to allow for lift. I would say those pencil lines are a bit high. Let the system cool and then see if that does increase a little

 

[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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When pressurising a combi/system boiler you need to allow for lift. I would say those pencil lines are a bit high. Let the system cool and then see if that does increase a little

Thanks. System is cooling now and pressure has dropped to 0.2 again

 

[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.