Excessive air in pressurised system

[Mark kennerley]

Looking for some advice about my pressurised CH. Had an extra zone added on for UFH and needed to have a 3 port valve replaced by a 2 port valve to prevent the rads being turned on when the UFH called for heat.

When the plumbers changed the pumps over they also installed a bypass to prevent boiler overheat (which made sense to me). Since then (and not saying it has been any fault of the plumbers who carried out the work) 2 towel radiators have been constantly filling with a substantial amount of air and need bleeding once a day at least.

I am also getting a very strange noise that is pretty disturbing as it happens early in the morning and sometimes late at night. It sounds like a fog horn and i have tried to reproduce the situation to produce the noise but have been unsuccessful.

Any advice to help with the noise and the stop the constant air ingress.

Thanks

 

[Best]

Fog horn noise is most likely a ball valve / fill valve on your cold water tank, or on a toilet cistern. Sometimes just a new washer needed.
The air in your system might be normal for a while after the system has been drained. Towel rails do gather the air first. If you have no auto vents on system that could suck air in, then just a case of keeping bleeding air for a few weeks. Do keep pressurising the water in heating system to correct bar pressure every time you bleed air out

 

[Mark kennerley]

Fog horn noise is most likely a ball valve / fill valve on your cold water tank, or on a toilet cistern. Sometimes just a new washer needed.
The air in your system might be normal for a while after the system has been drained. Towel rails do gather the air first. If you have no auto vents on system that could suck air in, then just a case of keeping bleeding air for a few weeks. Do keep pressurising the water in heating system to correct bar pressure every time you bleed air out

Definitely not a toilet cistern and we do not have a cold water tank. Yes i have been checking the pressure on the system each time and refilling as required. Think the work was done at the end of Jan so would the air be still coming out after this length of time?

Thanks for your thoughts

 

[Best]

It can take a few weeks to get all the air out of some systems.
Does the system stay in pressure?
And the fog horn noise issue, - do you have an unvented hot water cylinder?

 

[Mark kennerley]

It can take a few weeks to get all the air out of some systems.
Does the system stay in pressure?
And the fog horn noise issue, - do you have an unvented hot water cylinder?

Yes the pressure in the system seems fine even after bleeding of the rads. Yes i do have an unvented cylinder.

 

[Best]

Perhaps the noise is from the cylinder.

 

[heatservice]

Its possible that you have a micro leak on the inlet side of the pump, air is sucked in but water doesn't leak out, try adjusting pump speed or call back the installer.

 

[Mark kennerley]

Its possible that you have a micro leak on the inlet side of the pump, air is sucked in but water doesn't leak out, try adjusting pump speed or call back the installer.

We do not have a pump as it is a pressurised system. The only pump I have is on the UFH and OGB is definitely not that causing it. We have AAV’s fitted so could it be air escaping from those?

 

[Best]

We do not have a pump as it is a pressurised system. The only pump I have is on the UFH and OGB is definitely not that causing it. We have AAV’s fitted so could it be air escaping from those?

Heatservice I believe did mean your heating circulating pump.
The AAVs can suck air in if fitted on a pipe on suction side - like on a return pipe or just before a circulating pump.
To rule them out, hand tighten clockwise the wee air shut off screw on top or side of top of any auto vents that are on pipes. Remember some AAVs (like on boilers) are important to remain open to remove air, so might need to be opened again eventually. Although some are really only for convenience and manual vents are fine.

 

[Riley]

System boiler??

 

[heatservice]

We do not have a pump as it is a pressurised system. The only pump I have is on the UFH and OGB is definitely not that causing it. We have AAV’s fitted so could it be air escaping from those?

Sorry I didn't realize pressurised systems didn't use pumps, guess I wasted 45 years thinking I was a heating engineer 🙂

 

[Mark kennerley]

Sorry I didn't realize pressurised systems didn't use pumps, guess I wasted 45 years thinking I was a heating engineer 🙂

WHere would the pump be? I am assuming that it must be in the boiler unit itself so hence why I assumed no pump. The noise is definitely coming from the airing cupboard so I believe it is not the pump

 

[Riley]

You’d be surprised how sounds resonate on a heating system

 

[Riley]

What boiler is it

 

[Mark kennerley]

What boiler is it

Glow worm 30 sxi. I had wondered that but I have been downstairs when the noise has occurred and it was obvious that it was it was upstairs and not from the boiler

 

[heatservice]

WHere would the pump be? I am assuming that it must be in the boiler unit itself so hence why I assumed no pump. The noise is definitely coming from the airing cupboard so I believe it is not the pump

The moral of this story is: NEVER assume anything!

 

[Mark kennerley]

The moral of this story is: NEVER assume anything!

Thanks for that nugget of advice, have been looking at schematics of a condenser boiler and cannot see a pump in them. Where would a pump be?

 

[Riley]

So it’s a system boiler and will definitely have a pump in it

 

[Riley]

There are different types of condensing boiler system, heat only and combi, some will have a pump some won’t.

 

[Mark kennerley]

So it’s a system boiler and will definitely have a pump in it

Thank you for confirming.

 

[heatservice]

The noise is possibly from a fault with your combination valve, mains water pressure will often rise at night when there is less demand, can water be seen flowing through the tundish?

 

[Riley]

That’s a good shout. Is there a time that it’s more apparent

 

[Mark kennerley]

The noise is possibly from a fault with your combination valve, mains water pressure will often rise at night when there is less demand, can water be seen flowing through the tundish?

You assume that I know what a tundish is! Just googled it . Nothing seen outside where the overflow pipe is, I have been watching this as the expansion tank in the boiler failed and had to be replaced.

 

[Riley]

No guarantee that the boiler would terminate through the same pipe. Tundish tends to be for the unvented cylinder as a visual indicator of discharge.

 

[Riley]

I think the answer you need here is to get another Gas Safe and G3 registered engineer in to investigate as we don’t seem to be getting anywhere very quick with this