I have a combi system (Baxi 224) in a rented 1st floor maisonette that is losing pressure and by losing I mean dropping to 0 overnight. I first had a problem three weeks ago but assumed that it just needed topping up (was low but not 0). Yesterday the system failed ( 0 pressure) so I filed and reset - same thing this morning. I asked downstairs if there was any evidence of leaks in the ceiling (none visible) and none were visible in/around the boiler or radiators plus the pipe for the PRV didn't look as though it had extracted any water. After I had filled this morning, I waited for 5 minutes or so with the heating on and the pressure remained constant. The tenant will use the hot water later and will check to see if this affects the pressure. Not sure if there is anything else I can check - any ideas?
Combi system losing pressure
- Thread starter craig1234
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If the boiler has an expansion problem , nothing will show on that combi when only running HW, it will only show when running the CH, put the CH on for an hour and see what the pressure rises too.
If the pressure does not rise, with the boiler turned off disconnect the condensate discharge and see if a small amount of water appears, this would show a pinholed main heat exchanger and would account for no water leaks showing up, also if you can access the PRV discharge outlet, tie a small ballon, or freezer bag or similar and see if any water gathers in the bag over a 24 hour period or so
If the pressure does not rise, with the boiler turned off disconnect the condensate discharge and see if a small amount of water appears, this would show a pinholed main heat exchanger and would account for no water leaks showing up, also if you can access the PRV discharge outlet, tie a small ballon, or freezer bag or similar and see if any water gathers in the bag over a 24 hour period or so
Thanks Ian. I was perhaps slightly incorrect in saying that the pressure remained constant with the heating on - whilst I was there, it did rise slightly but then remained constant (but I was not there for long so don't know if over time it would have risen further). I can get access to the PRV outlet so will put a bag over it. I will also check the pressure (what am I looking for here - excessive rise and then a sudden drop (PRV) or something else?) and also disconnect the condensate and look there.
I just went round with my ladder to check the PRV outlet and it's bone dry so definitely nothing has been flowing through there. I will check the pressure rise, condensate discharge and will also isolate the flow and return on the boiler for a period of time to see what happens.
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yes good thing to do, but just be aware many boiler isolation valves will start leaking when they have been operated, but simply, if you do isolate them and the pressure still drops it is boiler side, if it stays constant and then when you open one of the valves the pressure drops immediately, the leak is on the system and not the boiler
So, received a phone call from the lady downstairs this morning to say that there was water coming through her light fitting! Real pain as that meant the problem was under the tiled bathroom floor. Took me ages to locate the problem (luckily I only had to break one tile as the others lifted). Can only blame myself as the problem was a dry joint on an elbow feeding the radiator - i did the plumbing over a year ago so surprising it's held up this long. Will check on the system in the morning.
Anyway, thanks very much for your help Ian - I have learnt a lot about combi systems and how to fault find in the future!
Anyway, thanks very much for your help Ian - I have learnt a lot about combi systems and how to fault find in the future!
I had a job this week a smell of gas, house was 39 years old and same owner since new, origional fitting never soldered , flux had held it all this time, dont beat yourself up these things are more common than you would think
Removing a cloakroom hand basin and pipework yesterday, one of the elbows on the cold water piping just pulled off as I moved the pipe. There was a small blob of solder under the fitting but none inside it. That had held for more than 20 years at mains pressure.
Reminds me of a rad change I did - drops from above , large system so I hired a freeze kit to save draining down . Pulled back the carpet - lucky I did - as I grabbed the pipe an old joint above the freeze point just fell apart. So I stood with my thumb over the pipe ! Luckily my M8 the decorator was there and between us we part drained and re did the failed joint . It was only his paint that was holding it ( and the other coats before )
I checked the system today and the pressure has not moved so all looks good. There is one thing that is nagging me though. When I replaced the elbow, (I use solder ring) and I couldn't get the solder to flow out the ends no mater how well I cleaned or fluxed (also no evidence of water before soldering). After the second attempt, upon removal, there was some tinning of the pipe so I think the joint would have been good. On the third attempt (this is the elbow that is currently in place), again no solder flowed out the ends but I think that both sides are good. Should I be concerned and have another go or leave it as it is?
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You must be doing something wrong if you don't get a visible ring of solder at both ends of the elbow.
- Joined
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Did you use a new Yorkshire elbow onto the tinned pipes ?
As well as cleaning the pipe, did you clean/polish inside the elbow?
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