Boiler losing pressure in winter only

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Like_knowlege
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Boiler losing pressure in winter only

Post by Like_knowlege »

I have a boiler (Vailant Ecotec 838 plus) installed in May 2016. It kept losing pressure in 2017 on an off to the point where almost every 2 weeks it went below 0.8 bar. There was a leak from one pipe from the boiler which was fixed. The following winter Vailant were called out as pressure was being lost and they replaced parts and still pressure kept being lost. Vailant came back (around November/December 2018) and a different part was replaced as the engineer stated that there was deposits on it which meant water was escaping. This was around winter time and no problems until last October (2019) when it became cooler and boiler on more for heating etc and I had to intially top up the pressure every 6 weeks and then 4 weeks and then 3 weeks. I did not call out the engineers and last topped it up in early Feb 2020 to 1.5 - 1.6 bar. It has lost around 0.3 bar since then (3 and a half months) and I do not expect it to be below 0.8 bar until the winter. It does not seem to be a leak in the pipes (ground floor are all under the ground as a raised floor and cannot see visible leaks at 1st and 2nd floor) so cannot confirm, but surely as it seems to lose pressure more in winter when boiler is on more than spring/summer when the boiler is on less for heating purposes means the problem is within the boiler itself rather than the pipework?

The property has wet underfloor heating covering an approximate area of 40 sq metres and then there is also 9 radiators (some double) in the 4 bedroom property (there are 2 two-port valves). Do boilers need topping up every 6 months or so depending on size of property and the associated length of pipes?

Any ideas as my warranty runs out in May 2021.
andy48
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Boiler losing pressure in winter only

Post by andy48 »

1. In winter you are likely to use the heating more, which would suggest to me the water is being lost in the heating circuit, not in the boiler.
2. Have you tried isolating the boiler flow and return pipes, thus isolating both UFH and radiator heating circuits? If pressure doesn't fall while isolated, issue is in the UFH or radiators. If it does fall, issue is within the boiler.
3. The flow and return are the two 22 mm pipes, one at each end of the group of 5 under the boiler. They already have isolation valves fitted, but be aware that these valve sometimes leak after they have been used, and replacements are expensive.
4. You can try wrapping a "bow" of tissue (the blue stuff is best) just under the nuts which connect each radiator valve to the pipework. Slight leaks, which may not be visible to the naked eye, dampen the tissue and cause the bow to sag.
Like_knowlege
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Boiler losing pressure in winter only

Post by Like_knowlege »

Thank you for your reply. In the past I have tried to turn off the valves and pressure did not drop but did once turned back on. I last did this over a year ago. This means that problem is in the pipes (either radiator or UFH).

The thing I do not understand is that pressure is pressure irrespective of it being winter or summer so why is more pressure lost in winter than summer. Is it not more to do with the boiler itself losing pressure as apposed to the pipes etc.

My understanding is that if the leak is below ground I cannot located it. The distance from pipes to tiles on floor is about 70cm so I cannot find it and all the area has UFH so even if the pipes that feed the radiators are leaking I cannot find out without ripping up the floor in one area and then ruining the UFH. This would be a massive cost to remedy.

Surely the leak cannot be too bad and I have been told that leaks will only get worse in time in pipework and they do not seem to be getting worse. i have been told losing 1 bar of pressure is maybe only 500ml to 1000ml of water.
andy48
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Boiler losing pressure in winter only

Post by andy48 »

1. The most likely place for leaks is in connection fittings. If you are lucky, the leak(s) will be in a joint to a radiator, hence the suggestion of the tissue "bows".
2. There are ways of locating leaks underground. It's a specialist field which I don't know about, but there are specialist leak detection companies.
3. Your insurance might well cover the cost of track and trace, i.e. finding the leak, including any digging. Might cover restoration to status quo, but won't cover cost of fixing the actual leak, but this is usually pretty cheap.
Like_knowlege
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Boiler losing pressure in winter only

Post by Like_knowlege »

Thank you for your reply. I think I am fully covered by my insurance company but really want to avoid the hassle and I can live with a potential small leak, unless it means I have to re-pressurise on a regular basis including spring and summer. I am covered for track and trace and making good. I estimate this will cost around 10K as tiles alone were £100 per square metre.

I have used a leak detection company before and they could not find the leak and I did in the end. I bought a cheap camera probe linked to an iphone off ebay and put it down a void from the main heating pipes coming down from the boiler and noticed brown marks on the white plastic pipes and stuffed a tissue there and in 24 hours there was around 50ml of water (as it weighed 50g more). That is how it was fixed initially. The leak detection company added gas to pipes and had a probe that detects it and found nothing. the engineer was also gas safe registered, and said it had to be the boiler. I have always used gas safe engineers and unfortunately found that they come up with different answers which do not always solve my problem
gas4you
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Boiler losing pressure in winter only

Post by gas4you »

Get the expansion vessel checked for its pressure.

Sounds as if it may have gone flat and boiler is over pressurising and letting water out of the safety valve when heating is on.
Dave

www.drlgas.co.uk
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