boiler pressure suddenly and randomly lost

[longrob]

Over the last year and a bit, I've noticed the pressure in our worcester bosch greenstar 37CDi has dropped to near zero a few times. In the last couple of months it seems to be happening more frequently, so I've since been monitoring it daily - checking it several times every day when the system is cold. The pressure has been at 1.5 bar when cold and around 1.9 when hot consistently - except for when this problem occurs: the pressure drops to near zero, it does so overnight - one day it's at 1.5, the next close to zero. It's done this twice in the last 10 days.

There is no sign of any leaks under the boiler, or any sign of discharge from the overflow pipes. Nor is there any sign of leaks from the radiotors or the pipework (that I can get access to). Judging by the time it takes to refill the system back up to 1.5 bar, there should be quite a lot of water /somewhere/ when this hapens, but so far I haven't seen any evidence.

The whole system (boiler, pipes and rads) were replaced a little over a year ago. The installer came a couple of months ago to service it and I mentioned what had happened (at that stage it had happened twice in the year but I had not been monitoring it daily so didn't know it was doing it so suddenly), but he didn't say much about it and I wasn't really concerned as it had only happened twice. I called him out a couple of days ago and he came, but charged a call out fee plus time spent and couldn't find anything wrong So that was money down the drain that I can't afford. The next day the pressure was near zero. I called him again and he was talking about changing some kind of pressure valve to see if it fixed the problem (with more call-out fee, parts & labour etc)

I can't afford to pay more money so I really need to try to find the problem by myself. Can anyone help ?

 

[yerino]

The expansion vessel is your problem.

 

[longrob]

The plumber came back this morning, and "isolated" the boiler (whatever that means). We've had no heating all day. He's been back just now and restarted the heating, and said there is no problem with the boiler, and since the radiators/pipework lost almost all pressure during the day, he concludes that there is a definitely a leak in the system, which sounds suspicious to me as it often happens spontaneously/suddenly. It's also rather gut-wrenching as we have had solid wood floors put down a few months ago so there is no easy way to get to the pipework.

Any advice ?

 

[longrob]

Can anyone offer advice about how to proceed ? Are there some tricks to locating a leak ? The latest info is this: as far as I can tell, the system has not lost pressure at all during the night time (when it's off). It only happens during the day. We previously had it set to come on at 5AM, so this was not apparent, but lately I changed it so it would still be off when we got up in the morning. Every time I have checked since, the pressure in the morning has been the same as the previous evening (around 1.5bar). But by mid evening it's consisntently down to below 1bar. Once it was at 0, and once it has not changed.

Please advise.

 

[dcawkwell]

Firstly give your heating engineer the push.

Get the boiler reconnected and running.

If there is still a leak check that there is no leak from
the pressure relief valve. Most likely cause.

You mentioned wood flooring. Good clue possibly they used nails/screws and went through a pipe. The pipe may only start to leak when hot.

I would connect the boiler to just the heating pipes upstairs after checking
boiler heat exchanger for leaks and the like.
Then run the boiler like this. If that cures the problem there is a leak downstairs.
I believe there is a service where by they come around with microphones and thermal imaging cameras to find the leak which sounds your best bet.
Air pressure in the downstairs pipes and listening for air release is also another option.

 

[longrob]

thank you !

If the pressure relief valve were faulty, water would come out from the overflow pipe outside, the house, right ? That's bone dry. I've also had a bucket underneath, and it's completely empty. There is a pipe from the boiler that connects to the house waste water pipe. I thought this was something to do with draining away condensate, but could the water from the system be finding it's way down there somehow ?

There are no signs on ceilings or walls that there is any leaks from above, and given the amount of water I'm having to fill up nearly every day, surely this proves the leak is downstairs ?

Thanks again.

 

[dcawkwell]

thank you !

If the pressure relief valve were faulty, water would come out from the overflow pipe outside, the house, right ? That's bone dry. I've also had a bucket underneath, and it's completely empty. There is a pipe from the boiler that connects to the house waste water pipe. I thought this was something to do with draining away condensate, but could the water from the system be finding it's way down there somehow ?

There are no signs on ceilings or walls that there is any leaks from above, and given the amount of water I'm having to fill up nearly every day, surely this proves the leak is downstairs ?

Thanks again.

Ok pressure relief is fine no problem there.
There is the possibility that the heat exchanger in the boiler is leaking and
that is running into the condensate drain but that is unlikely.
So that only leaves a leak in the system. Best way depending
on pipe layout is to isolate or just connect in the upstairs while finding
the leak downstairs. If you have suspended woodflooring (joists and floorboards downstairs) it is most likely that there is a leak here and
it is running under the house. Only takes a few litres to go from 1.5bar to 0 bar. So you are only probably only have a dribble of water but over a few hours that is enough.

 

[longrob]

Hi and thanks again.

Yes, we have suspended wooden floors downstairs (no cellar), except in the kitchen which is concrete. I remember that they concreted over one of the ch pipes that was running across the kitchen floor (the kitchen was previously also suspended). It makes me wonder if the concrete has sunk a bit and that's what's causing the leak somewhere.

 

[dcawkwell]

Hi and thanks again.

Yes, we have suspended wooden floors downstairs (no cellar), except in the kitchen which is concrete. I remember that they concreted over one of the ch pipes that was running across the kitchen floor (the kitchen was previously also suspended). It makes me wonder if the concrete has sunk a bit and that's what's causing the leak somewhere.

Unlikely. If they concreted over a copper pipe I hope they protected
the pipe first. Concrete eats away at copper. But this does takes years.

There is your answer you have a leak downstairs under the floors.
Floorboards up time. My bet would be a joint near a radiator or
piping through a doorway edging strip screws.
If plastic piping was use perhaps a connector that isn't pushed home all
the way.

 

[Agile]

I have not done this yet but suspect that listening with a mechanical stethescope at each rad pipe might identify the leak source.

Its odd that I dont seem to get called to many leaks these days.

Tony

 

[ColinEllen]

Hello Longrob,
We have exactly the problem which you described and expensive flooring which we would not want to / be able to take up.
What happened with your situation in the end? Did you identify a leak / find a solution??

 

[ianmcd]

ColinEllen the post you Hijacked is over 4 years old you would be better starting a fresh post