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Ask The Trades › DIY Forum › Plumbing Questions › UFH airlock?

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UFH airlock? (Read 5527 times)

OrdinaryJo

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UFH airlock?
Nov 14^th, 2010, 12:15pm

We have UFH - 2 sets of manifolds, 1 dedicated boiler (hot water and radiators are on another boiler/sysem).

Its been in for 4 years. The circuits off one manifold are not heating up. The thermostats are sending a signal to the manifold which is then sending the signal to the boiler & pump. I can see these lights switching on etc.

The boiler is cycling. I thought that sealed UFH systems dont get airlocks, but this looks like it does.

The boiler is sending hot water to the manifold which is not working. The pipe is hot to touch just as it comes out of the boiler, but a few metres away, the pipe is lukewarm and not warm at the manifold.

Any tips? I dont know how to refill the system.

The various pumps are now making lots of noises, especially after I opened and closed a few valves (whoops!)

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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: UFH airlock? Reply #1 - Nov 14^th, 2010, 12:34pm You use the filler loop that fill the boiler/system, what is the pressure gauge reading, possibly the two problems are related. There's a vent and a drain on the manifold (may look like a drain cock)
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OrdinaryJo

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Re: UFH airlock?
Reply #2 - Nov 14^th, 2010, 3:20pm

thescruff wrote on Nov 14^th, 2010, 12:34pm:

You use the filler loop that fill the boiler/system, what is the pressure gauge reading, possibly the two problems are related.

There's a vent and a drain on the manifold (may look like a drain cock)

Thanks - the pressure had dropped to zero.

I upped the pressure, went back to the manifold & saw a big leak !!!

Its from the top of the temperature control valve. See pic below

I've turned off the system, de-pressurised but not sure what to do next. Its not a diy job I think !

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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: UFH airlock? Reply #3 - Nov 14^th, 2010, 3:29pm I assume you mean the blender, is there a gland under the cap that can be pinched up. Do you know how to re-pressure the boiler with the filling loop or whatever it has, if not post the make and model.
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OrdinaryJo

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Re: UFH airlock?
Reply #4 - Nov 14^th, 2010, 4:20pm

thescruff wrote on Nov 14^th, 2010, 3:29pm:

I assume you mean the blender, is there a gland under the cap that can be pinched up.

Do you know how to re-pressure the boiler with the filling loop or whatever it has, if not post the make and model.

It was the blender - I had opened it when there was no pressure, and when I pressured up again, it started leaking.

I've tightened it now.

There is hot water now up to about 5 metres from the manifold, but it cools down, and no hot water still at the manifold.

The boiler is a Halstead Eden vB - does that need re-pressuring?

I've repressured using pressure tank - see below

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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: UFH airlock? Reply #5 - Nov 14^th, 2010, 4:26pm The gauge should read 1.2ish bar. Is there a fitting on the manifold to let the air out, the MV should be open manually.
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CWatters Super Member Offline "Daddy fick it" says James Posts: 5150 Total Thanks: 58 For This Post: 0 Gender:	Re: UFH airlock? Reply #6 - Nov 14^th, 2010, 5:11pm Is that valve on the left in the photo working?
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OrdinaryJo

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Re: UFH airlock?
Reply #7 - Nov 17^th, 2010, 10:33am

thescruff wrote on Nov 14^th, 2010, 4:26pm:

The gauge should read 1.2ish bar.

Is there a fitting on the manifold to let the air out, the MV should be open manually.

Thanks very much for the advice. I didnt have the hose to release the airlock, so I had to get a plumber in.

It turns out that the system just needed re-pressuring - but before I had done that, I had closed down a couple of by pass valves which meant the hot water was not getting to the second manifold.

There is a problem with the system - the temperature regulator on the blender is stuck - so thats why when I was turning it, water was leaking out as I was effectively opening it up, rather than increasing the temperature. Plumber says I need a new one, and hes gone to get one.

Morale is - for any pressurised system - check the pressure first before opening valves etc.

Thanks for all the advice on here from "thescruff" - much appreciated.

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