Boiler losing pressure

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Purple

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My Vokera gas boiler is losing pressure over a 5-7 day period. It drops from 1.5 bar to zero and then the boiler knocks itself off. When I open the value and increase the pressure it works again. Does anyone have any suggestions as to why this is happening, does it mean that there is a leak in the system?
 
The water is going somewhere, if the leak is on the boiler you will see evidence of it under the boiler, if it's going out the discharge pipe you will see it dripping from the pipe outside (if it's fitted), you can put a bottle under it to monitor it, if it turns out it's coming out of the discharge pipe then there may be issues with the boiler building up to much pressure and discharging itself for safety, if so call a engineer, if it's none of the above then the chances are you have a leak on your system pipework, which a good plumber should be able to deal with, remember to have your system water checked as refilling all the time can cause the inhibitor(if added) to be diluted or ineffective leading to dirty water which is a big problem in it's self.
 
Gary71 pretty much sums it up: a drop in pressure over a short period of time is a pretty good indicator of a leak in the system. Check all radiators and valves for tell tale signs. If you're lucky it may just be a leaking gland packing on a valve; this would be a quick and cheap fix.
 
Thanks guys, can anyone recommend a good plumber in south Dublin (Rathfarnham area)?
 
you can get a leak sealing agent that you can put into your system, it comes in a silcone type tube. all you need to do is close one rad using the valves on either side of it, unscrew the vent at the top of the valve and let the water out into a container. there won't be much water, then smiply and very slowly add the agent through the vent hole, be careful not to lose the vent. when its all in, screw the vent back in and turn on valves both sides to let agent circulate around syste. this works on very small weeps and leaks. If you do decide to get a plumber ask them to check you expansion vessel as this may need to be pressurised,
 
Tried leak sealing agent before - but no good. I think it only works on pin-hole leaks. More for car engine stuff than heating system.

Look for signs of leak.
- Damp spot on skirting board.
- walk on bare feet when heating on - look for warm spot in floor.

And then starting digging to fix leak.

I went through this 2 years ago - its painful. Especially if you have wooden floors.
 
its true, that it only works on small leaks but if the pressure is dropping over a 5-7 day period, then its only a very small leak. I have about an 80 per cent success rate with the agent. its def worth a try first. If that fails you can hire a company that will find the leak using ultra sound and basically put an x on the floor so your plumber has a starting point. very expensive tough, 600 euro and beyond.
 
DavyJones said:
its true, that it only works on small leaks but if the pressure is dropping over a 5-7 day period, then its only a very small leak. I have about an 80 per cent success rate with the agent. its def worth a try first. If that fails you can hire a company that will find the leak using ultra sound and basically put an x on the floor so your plumber has a starting point. very expensive tough, 600 euro and beyond.
Click to expand...
Thanks Davy. I suppose it would still be cheaper than finding it any other way.
 
Investigating the pressure vessel is a most sensible suggestion indeed

Domestic type leak sealer will not work if the pipe is not open to air
rarely works on burried pipes

Let building fabric cool down for two days then run heat and use infra-red thermometer to detect hot spot remember concrete will only be hotter where water seeps from end of lagging if armaflex type

remember when fixing allow for the original expansion and contraction that caused the leak in the first place.
 
I had a similar problem in my last house, pressure would drop to zero over a week or so - took a bit longer to drop when the CH was not in use (summer time). Eventually tracked it down (by chance) to a tiny pinhole leak in a poorly soldered capillary joint under a rad. Repressurising the system took all of 20 seconds or so, once a week. Faced with a huge bill from an ultrasound detective, I'd live with the leak and just repressurise regularly meself ;)
 
If a pressure vessel has a little air in it you will have to pressureise the system less often. I earn my living putting air into depleted pressure vessels.
 
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