Gurgling radiator after using tap

[Ade75]

Hello,

A slightly strange one, that a heating engineer has yet to work out - hoping that someone could offer some guidance!

I have a combi boiler, located downstairs in the kitchen. Whenever certain taps (esp downstairs cloakroom) are used, air bubbles up into the radiator in our attic bedroom. Clearly, hot water and heating systems are (/should be) completely separate. Is there an obvious cause for this happening? Perhaps the 'shock' of the tap being shut off, or the brief fire up of the boiler when hot water is requested?

Thank you,

Adrian

 

[Jurassicspark]

Hmm, I am probably wrong, but the only think I can think of is if the diverter valve inside the boiler is malfunctioning, it could allow the slightest amount of hot water to mix with the central heating circuit potentially causing air to be carried into the radiator system when you use the hot water taps...

 

[Ade75]

Hmm, I am probably wrong, but the only think I can think of is if the diverter valve inside the boiler is malfunctioning, it could allow the slightest amount of hot water to mix with the central heating circuit potentially causing air to be carried into the radiator system when you use the hot water taps...

That's a good thought, thank you.

 

[vitor710]

That's a good thought, thank you.

Hi! Did you find the root cause?

Have a similar issue. One radiator has a gurgling or rushing water sound after the hot water tap is turned off.

Thanks.

 

[Ade75]

I haven't found a cure yet. Boiler has just been serviced, and all seems OK on that side. I'm checking the entire system for leaks. Fearing that perhaps there is a problem somewhere not easily accessible...

 

[Madrab]

It will be to do with the boiler switching over and the flow starting up again in the system and it's moving past a noisy valve, especially given it's at the top of the house where any air in the system will naturally gravitate to. Do you find that rad needs bled more often?

 

[CountryFan]

Does the radiator heat up with the others? Is the filling loop still connected?

 

[Ade75]

The radiator heats pretty well. I am venting it every few days, but only a small amount of air. I'm not sure re the filling loop (apologies, I am definitely a plumbing novice!). The filling key (if that's the right term) has been stuck in place for years.

 

[CountryFan]

The radiator heats pretty well.

Then I doubt it’s connected to the water side

I'm not sure re the filling loop (apologies, I am definitely a plumbing novice!). The filling key (if that's the right term) has been stuck in place for years.

Loop/key same outcome different connections. It does say in the instructions to remove the key when filled, if there’s backflow prevention then this may have failed.

I am venting it every few days, but only a small amount of air.

Then you have a leak or there’s a hydrogen buildup in that radiator

 

[Ade75]

Thanks. The radiator in question is relatively new, so do you think a pipework leak (or perhaps issues in the boiler itself) is most likely? I will recheck all visible pipework. There is some green staining around some connections, which I assume means a small leak (either current or historic). Would that be enough to pull in air, or is there potentially a larger issue, would you think?

 

[Ade75]

Once I've rechecked and tightened all connections, I assume my next step is to bring in the experts?

 

[CountryFan]

I would certainly give it a looking over, it’s losing water/generating hydrogen somehow.

Once I've rechecked and tightened all connections, I assume my next step is to bring in the experts?

You could do, but see how you get on first.

 

[Ade75]

I also have an issue with dampness under a wooden block floor. We live in a low lying area that floods on occasion, so I have put that down to rising damp rather than a leak. It could of course be linked to the heating system issue, but I am reasonably confident that no cental heating pipes run under it (all ground floor rads are fed from above). If everything else looks OK, I may need to get a specialist leak detection company to see if there's an issue under that floor..

 

[Madrab]

Do you get frequent pressure drops @ the boiler, have to top up regularly?

 

[Ade75]

No, nothing substantial in term of pressure drop