I am scratching my head with this one. Our house has full downstairs UFH, towel rads in 3 lower onsuites and 2 recent upstairs on suites that appear to be connected to the primaries, and 2 standard rads in the upstairs rooms. One of the upstairs towel rads seems to continuously collect air. Definitely not hydrogen. Most of the plumbing appears to be in speed fit and I can only assume I must have a leak although I have not had to top up the water at all and pressure seems ok.i did have an issue with the pressure increasing although since I had the boiler pressure vessel topped up as it was empty of air, I am debating adding some UV dye to try and check if I can spot any weeps at all. Tried paper towels on rad connections and not spotted anything although there is a lot of pipework in the eves that I have checked by hand only. Does anyone have any suggestions on where to start with this or any experience with dyes(including recommendations)
Air in sealed system
- Thread starter zooankski
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If you have central heating pipework in the loft, it could be worth fitting air vents up there.
If you are releasing air and not having to top up, then water must be entering the system from somewhere. Check your pressure vessel again.
I will check the vessel again next week when I am off of my work shift pattern. It was empty previously and the boiler pressure would rise to a point. On one occasion I bled the towel rad and pressure dropped to back to normal. Filling loop is disconnected so not adding any water.
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This issue is seriously doing my head in! EV is ok. i still have air in the rads although i suspect i may have a tiny leak as pressure on the boiler is a fraction lower when cool.
Has anyone had any experience using dyes to locate leaks? Is fluorescien suitable for this purpose? I have visually inspected as many of the pipe joints etc as possible and found nothing.
All rad tails and the UFH manifold connections wrapped in paper towel and all seem dry.
99% of the pipe work is in barrier pipe so a dye might work well?
Only thing i need to try is the balloon over the boiler PRV pipe and check of condensate pipe although both look dry.
Has anyone had any experience using dyes to locate leaks? Is fluorescien suitable for this purpose? I have visually inspected as many of the pipe joints etc as possible and found nothing.
All rad tails and the UFH manifold connections wrapped in paper towel and all seem dry.
99% of the pipe work is in barrier pipe so a dye might work well?
Only thing i need to try is the balloon over the boiler PRV pipe and check of condensate pipe although both look dry.
When charging air side of EV, the water side must be empty and open to atmosphere. Isolate boiler from CH and drain boiler, if EV is inside boiler. If separate then isolate EV from pipework.
Looks like I must have a very small leak I think -
System pressure appears to drop slowly, only after I bleed the towel rads.
I have been over the system from top to bottom but cannot see anything obvious.
The other possibility is that our UFH downstairs has an issue although I think the chances of that are slim unless it is at the manifold.
I have wrapped most joints in kitchen towel but not found anything although the water could easily be evaporating off before detection.
I am considering either a UV dye, although this seems expensive, or fluorescein which is readily available and apparently also shows up better under UV?
I have not found much info using the normal search methods so hoping someone may have experience of using a dye and what type?
System pressure appears to drop slowly, only after I bleed the towel rads.
I have been over the system from top to bottom but cannot see anything obvious.
The other possibility is that our UFH downstairs has an issue although I think the chances of that are slim unless it is at the manifold.
I have wrapped most joints in kitchen towel but not found anything although the water could easily be evaporating off before detection.
I am considering either a UV dye, although this seems expensive, or fluorescein which is readily available and apparently also shows up better under UV?
I have not found much info using the normal search methods so hoping someone may have experience of using a dye and what type?
Draw straight lines on tissue paper using water based ink ( not ball point ) and wrap the tissue where you suspect there is a leak. Leaking water will smudge the lines even if it does evaporate before you can inspect the paper.
, will give it a go.
That is normal, if you bleed any part of your sealed system then you will have to top the pressure back up even if it is only water that comes out
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True but if it was air that came out, how did the original water get replaced by air! Could be sucking in air via a leak but the water still came out somewhere.
The Venturi effect can happen anywhere there is a fitting, the action of a circulating pump can reduce the system pressure to less than atmospheric in localised spots.
R
rules&rulers
Sounds like the system is pulling in air and dumping it in the towel rail (highest part of the radiator circuit) seen it a few times. usually down to a micro water leak suction side of pump But system design,system components,corrosion,boiler type,and a few more also need consideration.
My entire UFH manifold is now wrapped in loo roll covered in blue felt tip lines. Next step, all rad tails which i have nipped up and do show some signs of corrosion. If this doesn't give me a clue to what is going on then i have no idea.
I am starting at the UFH manifold as it is mounted in a cupboard and there is always a warm moist smell there. No visual signs and perhaps due to a large lump of metal in a small space but worth a shot.
Once it warms up a bit more then i might isolate the UFH completely and see what happens.
I am starting at the UFH manifold as it is mounted in a cupboard and there is always a warm moist smell there. No visual signs and perhaps due to a large lump of metal in a small space but worth a shot.
Once it warms up a bit more then i might isolate the UFH completely and see what happens.
@jeff the gasman is the expert on this subject
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