Heating Lost Pressure

clueless456 · Oct 25, 2023

Hi, I realise this is an electrical forum and not plumbing, but was wondering if somebody could help.

My heating is not working and the heating pressure guage has dropped to zero. The black valve you can see to the right of the photo cannot be turned and is locked in place. I cannot see any other valve, or screw to turn to increase the pressure back to normal. Should there be another valve switch somewhere?

Does anyone know what I can do to increase the pressure on the guage? I would really appreciate any help, as would prefer not to have to call out a heating engineer.

Many Thanks

DPG · Oct 25, 2023

The black tap will probably have seized due to lack of use. But if the pressure has dropped suddenly rather than just gradually over time, then it points to an issue somewhere in the system

clueless456 · Oct 25, 2023

DPG said:
The black tap will probably have seized due to lack of use. But if the pressure has dropped suddenly rather than just gradually over time, then it points to an issue somewhere in the system

The black tap looks to be screwed in place with a little screw stopping it from moving. I haven't tried unscrewing it, as I assumed it was locked in place for a reason?

DPG · Oct 25, 2023

clueless456 said:
The black tap looks to be screwed in place with a little screw stopping it from moving. I haven't tried unscrewing it, as I assumed it was locked in place for a reason?

The screw just holds the plastic tap on to the metal spindle of the valve. Try again with more force. The worst that will happen is the black tap will spin and do nothing.

clueless456 · Oct 25, 2023

DPG said:
The black tap will probably have seized due to lack of use. But if the pressure has dropped suddenly rather than just gradually over time, then it points to an issue somewhere in the system

Problem solved and pressure now sorted. The black tap was just stuck and extremely stiff, but just managed to turn it.

Thank you for speedy reply.

DPG · Oct 25, 2023

clueless456 said:
Problem solved and pressure now sorted. The black tap was just stuck and extremely stiff, but just managed to turn it.

Thank you for speedy reply.

Nice one. Keep an eye on the pressure over the next few hours/days to see if it starts dropping.

clueless456 · Oct 25, 2023

DPG said:
Nice one. Keep an eye on the pressure over the next few hours/days to see if it starts dropping.

Thank you. The pressure has dropped a little since it was reset - What things could cause this? Could it be caused by having heating up too high / too many radiators on / radiators o too high etc?

Should the pressure always remain at the same level, or is it normal to go up & down?

DPG · Oct 25, 2023

clueless456 said:
Thank you. The pressure has dropped a little since it was reset - What things could cause this? Could it be caused by having heating up too high / too many radiators on / radiators o too high etc?

Likely a pressure leak somewhere. Either in the heating system itself, or somewhere in the pipes/radiators.

Someone with better plumbing knowledge than me will hopefully be able to help a bit more.

Pressure vessels in combi boilers often leak, bit I'm guessing that red tank in your picture is an external pressure vessel?

littlespark · Oct 25, 2023

Bleed the radiators, then up the pressure again.

Air inside the rads compress more than water.

clueless456 · Oct 25, 2023

DPG said:
Likely a pressure leak somewhere. Either in the heating system itself, or somewhere in the pipes/radiators.

Someone with better plumbing knowledge than me will hopefully be able to help a bit more.

Pressure vessels in combi boilers often leak, bit I'm guessing that red tank in your picture is an external pressure vessel?

Thank you - I don't know if it's an external pressure vessel... I am a bit clueless with things like this.

clueless456 · Oct 25, 2023

littlespark said:
Bleed the radiators, then up the pressure again.

Air inside the rads compress more than water.

Thank you for the speedy replies. I'm sure I have a radiator key somewhere - It might be in a box somewhere in the garage.... I will try to find it.

littlespark · Oct 25, 2023

Bleed the rads when they’re cold.

Heating up the water increases pressure within the system anyway, but it expands into the air within the rads… and with the circulating pump running, it brings the overall pressure down.

If it’s like a combi boiler, optimum pressure should be between 1 and 2 bar when cold. Maybe a green mark on gauge showing good range.

clueless456 · Oct 25, 2023

littlespark said:
Bleed the rads when they’re cold.

Heating up the water increases pressure within the system anyway, but it expands into the air within the rads… and with the circulating pump running, it brings the overall pressure down.

If it’s like a combi boiler, optimum pressure should be between 1 and 2 bar when cold. Maybe a green mark on gauge showing good range.

Ok, thank you for the tip on bleeding them when cold. I have just ordered a radiator key, as not sure if I can find mine.

There is no green mark on the guage, but I reset it to the level marked on the bar which is set at just below 1.5... It has now dropped down to just below 1.

James · Oct 25, 2023

bear in mind that if you bleed air out of the radiators, the pressure will drop. you will have to add more water after bleeding to bring it up to the required pressure.

nicebutdim · Oct 25, 2023

Guage dropping to zero, then back from 1.5 Bar to 1.0 in a short space of time might be something more than air needing bled out of the system.

Is this the first time you've used the heating for some time or had it been working okay until recently?

clueless456 · Oct 25, 2023

James said:
bear in mind that if you bleed air out of the radiators, the pressure will drop. you will have to add more water after bleeding to bring it up to the required pressure.

Thank you - I have never heard of having to top radiators up with water after bleeding bleeding before... Please could you provide clear instructions of how this is done, and how much water?

clueless456 · Oct 25, 2023

nicebutdim said:
Guage dropping to zero, then back from 1.5 Bar to 1.0 in a short space of time might be something more than air needing bled out of the system.

Is this the first time you've used the heating for some time or had it been working okay until recently?

It had been working fine before last night.

James · Oct 25, 2023

nicebutdim · Oct 25, 2023

clueless456 said:
Thank you - I have never heard of having to top radiators up with water after bleeding bleeding before... Please could you provide clear instructions of how this is done, and how much water?

You don't top up individual radiators, but the system (as you did earlier) as pressure may drop if quite a lot of air has to be bled from it.

clueless456 said:
It had been working fine before last night.

There may well be air needing bled from radiators, and this is definitely worth doing, but I suspect something more is at play. Sudden loss of all pressure and 1/3 additional loss a short time later isn't normal. It may be a cheap and simple fix, but more than likely it's time to call a plumber/heating engineer.

clueless456 · Oct 25, 2023

nicebutdim said:
You don't top up individual radiators, but the system (as you did earlier) as pressure may drop if quite a lot of air has to be bled from it.

There may well be air needing bled from radiators, and this is definitely worth doing, but I suspect something more is at play. Sudden loss of all pressure and 1/3 additional loss a short time later isn't normal. It may be a cheap and simple fix, but more than likely it's time to call a plumber/heating engineer.

Oh Ok, thank you, I understand. I will bleed the radiators first and see if there are any further problems first. I have the hot water switched on constantly sometimes - Could that maybe be the cause of the problem?

There has been an issue with low water pressure in the bathrooms since moving home - Could that also be due to the radiators needing to be bled?

If I made the pressure guage higher (such as 2, instead of 1.5), would that increase the water pressure in bathrooms?

DPG · Oct 25, 2023

clueless456 said:
Oh Ok, thank you, I understand. I will bleed the radiators first and see if there are any further problems first. I have the hot water switched on constantly sometimes - Could that maybe be the cause of the problem?

There has been an issue with low water pressure in the bathrooms since moving home - Could that also be due to the radiators needing to be bled?

The house water pressure won't affect your heating system pressure - they are not connected, apart from when you top up you heating system using the black filling valve.

clueless456 · Oct 25, 2023

DPG said:
The house water pressure won't affect your heating system pressure - they are not connected, apart from when you top up you heating system using the black filling valve.

Ok thank you - Is there anything I can try to make the bathroom water pressure better?

DPG · Oct 25, 2023

clueless456 said:
Ok thank you - Is there anything I can try to make the bathroom water pressure better?

Might just be generally low in your area - speak to neighbours to see what theirs is like. If not then make sure your stoptap is fully open (but give it half a turn back in to prevent it sticking).

Sorry, is it just the bathroom? If so then do you have individual isolators for the taps?

clueless456 · Oct 25, 2023

DPG said:
Might just be generally low in your area - speak to neighbours to see what theirs is like. If not then make sure your stoptap is fully open (but give it half a turn back in to prevent it sticking).

Sorry, is it just the bathroom? If so then do you have individual isolators for the taps?

When you say stoptap, do you mean the main water stopcock?

Yes just the bathrooms, the other sink taps in bathrooms and other areas of house have an ok pressure... There is an electric shower in the WC and another electric shower in en-suite, and the main bathroom has shower attachment to taps on the bath. Both of the electric showers have very poor water flow pressure, and the shower attachment on the bath taps is very poor pressure too.... The bath taps themselves and the sink taps are ok.... I have replaced the shower head on the bath with a new "power shower head", but still very poor water pressure through the shower heads.

I am not sure what you man about isolators for the taps? Do you mean electrical isolators?... The shower attachment attached to bath taps has a switch to alternate between taps & the show head. The other 2 showers are electric wall fitted shower units.

littlespark · Oct 25, 2023

He means something like a ball valve on the pipework that can shut off individual taps.

Your heating… the boiler, radiators and pressure vessel is a closed system that has nothing to do with the pressure at your taps and shower.

We do have a sister forum here so maybe register and ask the question there?

We’re clever, but we do like to let the plumbers answer a few questions now and again.