Air in towel radiator

[Sammy1]

Our upstairs towel radiator keeps filling with air at the top. We had a new system boiler, new tank and new pipework fitted in October. The new tank is in the garage which is underneath the house and the new boiler is in the kitchen at ground floor level. We also had underfloor heating installed in our kitchen, the manifold is in the garage under the house. The 3 towel radiators come on when either the hot water is on or the underfloor heating is on, but not when the other radiators are on. We keep needing to let air out of the upstairs towel radiator and top the boiler up with water at the same time. The pipes in the walls and under the floors are no longer easily accessible. Where is the air coming from and how do we fix it? Please help!

 

[king of pipes]

There seems to be 2 x red exp. vessels and 1 x white, one red is adjacent to the boiler?, what volume is this.
You can tell easily if the installed exp. volume is sufficient by turning on all heating systems and noting the boiler pressure when all systems hot, if not > 2.5bar then OK from a expansion point of view but maybe other reasons for installing extra one?.
Can you also post a close up photo of the UPM pump, don't know if its running on one of its manual modes or is PWM controlled.

???

 

[Sammy1]

???

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There seems to be 2 x red exp. vessels and 1 x white, one red is adjacent to the boiler?, what volume is this.
You can tell easily if the installed exp. volume is sufficient by turning on all heating systems and noting the boiler pressure when all systems hot, if not > 2.5bar then OK from a expansion point of view but maybe other reasons for installing extra one?.
Can you also post a close up photo of the UPM pump, when its running, don't know if its running on one of its manual modes or is PWM controlled.

The photos of the red ones are not my house. Pressure does not go over 2.5. What is the UPM pump? The black box near the water tank?

 

[Sammy1]

I'll go into it later I'm now got to work 😉👍 regards kop

Thank you 👍

 

[John.g]

The photos of the red ones are not my house. Pressure does not go over 2.5. What is the UPM pump? The black box near the water tank?

Apoligies, the red ones are atypical as shown by KOP.

2.5bar is OK for the moment as long as you don't install any more rads etc.
Re Air venting, when you vent the air, then theoretically, if you don't top up the system, if air is entering the system the pressure should build up again, if it doesn't then perhaps air still in the UFH loops even though this might be unlikely since last October, anyway, after the next venting do not top up except that the pressure is excessively low and see what happens.

The Pump is on the UFH manifold as shown, you might post a close up photo of it when running to show the LEDs.
Also if you can see the UFH manifold, the flow rates for each loop and the manifold flow and return temperatures, if available.

 

[king of pipes]

Thank you 👍

One other thing to try is tie wrap a plastic bag on the end of the safety valve of the boiler for 24 hrs run the system heat the water and just monitor if any water is in the bag ? I am working on a large 5 bed house on a insurance job this is a more typical install I have to add I didn't install it but I know the Engineer who did 👍

 

[milleniumaire]

"We also had underfloor heating installed in our kitchen, the manifold is in the garage under the house. "

I thought it was necessary for a UFH manifold to be installed ABOVE the UFH pipes that it supplied? Usually, the manifold has an auto air vent, but if this is below the underfloor heating, it wouldn't have any effect as air rises to the highest point, possibly to the top of the towel rails.

I assume the affected towel rails are at the highest point in the heating system?

What would happen to an auto air vent on an UFH manifold that was installed lower than the UFH? Is it possible air could get into the system? I suspect not, but this is the only thing that jumped out at me regarding your setup.

 

[John.g]

Some towel rads also have electric heating elements which have been known to draw air in via the rubber gaskets.

 

[ShaunCorbs]

Aslong as it’s purged of all air the ufh will work fine if the pipe is above the manifold

 

[Sammy1]

Aslong as it’s purged of all air the ufh will work fine if the pipe is above the manifold

Thanks all, after letting the air out of the towel rails several more times the problem seems to have resolved. I think it may have been air trapped in the system from the installation but will keep an eye on it.

 

[John.g]

Thanks all, after letting the air out of the towel rails several more times the problem seems to have resolved. I think it may have been air trapped in the system from the installation but will keep an eye on it.

There have been numerous posts about air collecting in towel rails, is it because the top(s) of the towel rails are generally higher than any other rad top(s)?.

 

[Chuck]

There have been numerous posts about air collecting in towel rails, is it because the top(s) of the towel rails are generally higher than any other rad top(s)?.

Seems plausible to me. Another, not mutually exclusive, possibilty is that the towel-rail design means that a relatively small amount of air results in a cold 'top rail' and people notice this when they put the towel on or take it off.

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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