Sealed system - Losing pressure every day... condensate??

[Jumpy]

I have a sealed c/h system with a Worcester Bosch Greenstar 24Ri boiler. But I lose all pressure every day, yes within 24 hrs or probably abour 5 hrs of heating and 1.5 hrs of hot water!!

Cant find a leak anywhere, and can see about 90% of all pipework.

Expansion vessel pressure is good.

Not coming from overflow, so pressure isnt building up and releasing water.

Put valves all over the place, so isolated upstairs, downstairs and each rad - nothing.

Seen a lot of posts on various forums about people moaning about losing pressure over a week or 2.. if only!!!

Latest idea has been the condensate pipe - so cut it and put a bucket under. After 1 hr of hot water and 2 hrs of c/h theres just over 300ml of water in the bucket.

Is this normal!? Seems a lot to me, but I cant find info on how much should come out.

Can anyone help???
Please - to make matters worse the vessel and filling loop are in the loft, so I'm getting fed up with going up at 5 every morning to let mains water in (about 5-10 seconds' worth) to let the system fill then heat!!!

 

[cross thread]

poss coil in cylinder leaking .try isolating flow return to cylinder to prove.if heat ex leaking it would come out of condensate with boiler off .so turn off and check

 

[Jumpy]

THanks for that - I had previously ruled out a leak in the coil as I thought I'd have noticed the hot water being discoloured due to inhibitor - but of course that's all long gone!

I'll put a couple of isolator valves on it and give it a go - wont be too popular going without hot water with a 2 yr old but hopefully worth it!!

Condensate doesnt com out when boilers off so prob not heat ex - still dont know how much condensate is normal though.

Thanks v much for the idea - it makes sense.

 

[45yearsagasman]

Maximum condensate rate is about 2 litres per hour. That's from the manual.
Please don't run the boiler with a cut condensate, especially if the cut is indoors.

 

[Jumpy]

Thanks for the reply and the condensate max, I must have missed that in the manual - I will be sealing the cut with a connector now I know its not the heat ex, but I dont understand what the risk is running with the cut / open pipe???

 

[JBPHS]

Thanks for the reply and the condensate max, I must have missed that in the manual - I will be sealing the cut with a connector now I know its not the heat ex, but I dont understand what the risk is running with the cut / open pipe???

Technically, the condensate pipe is part of the flue system. If the trap inside the boiler for whatever reason was not full, POC's (products of combustion) including gases such as Carbon Monoxide could spill into the living area.

James.

 

[Agile]

And when they spill into the living room then they could kill you.....

 

[stardanny]

Cant find a leak anywhere, and can see about 90% of all pipework.

What the other 10%? Is it buried? Under ground floorboard?

Also have you check water isn't coming out of pipe from PRV?

Daniel.

 

[Jumpy]

The other 10% is probably a lot less - its just where the pipework goes in the walls from upstairs to downstairs.

most of the rest is jointless runs of plastic that I've replaced over the years, and downstairs is in void under floorboards (30's build) so I can see it all.

Also put a bucket under the tun dish from the PRV.

I must be losing about 1 - 2 pints a day so I'm sure I'd see it leaking through wherever.

Only 2 places left are the coil in the tank or in the boiler somehow?

I'm stumped. Had plumbers out, but theyre not much more use as its just a case of finding the leak???

 

[stardanny]

When did it started losing water? Have you done any work prior to heating losing water?

I had a case where owner had nail a picture hook on wall and hit heating pipe in void behind plasterboard and it leak along the pipes down to ground floor and not seen till we found it.

Daniel.

 

[andytw]

Do you lose pressure when the system is cold and left alone ?

 

[ScottishGasMan]

The RI boilers don't have much of an Issue with internal hex/condensate leaks, it was the CDi heat exchanger that is known for that problem.

Silly one, but you checked round the outside of the house for a dripping drain off valve? There often not where the boiler is, and I know a few folk that have torn their houses in two looking for leaks to find the drain valve outside at low level dripping into stones or soil

 

[Jumpy]

Had the system changed to sealed 1 yr ago because it was too noisy (!) - told this was due to the pump being to close to the pipe that vented into the header tank - so it was drawing in air - seemed to make sense.

Anyway, had it sealed - just as noisy since then as the air gets in so pump is very annoying.

Now - here's the weird bit...

After heating has been on and noisy for 30-40 mins the noise gets louder for 5 or so seconds then it goes quiet. Still loses pressure but the annoying sounds go and heating works fine.

BTW - Have avoided using leak sealer chemicals as I've been told they can do bad things to boilers - but I may have to give it a go.

I havent left it off for any amount of time to check if still leaks - but all through summer with just an hour of hot water a day it still needed topping a couple of times a week, so not as often but still a pain.

Havent been hammering any nails into walls!

Drain off valve: If you mean the PRV - nothing comes from that, had it running into a bucket for 2 wks with no water collecting. If you mean the condensate pipe I ran that indoors a couple of years ago because when it was outside it kept freezing.

Thanks for all the ideas so far guys - It is definitely an odd one. I've been thinking about putting UV dye in the system to trace any leaks, anyone any idea of how much you should put in???

 

[Nozzle]

My plumber offered a good hint for trying to track down a leak - chuck in a bit of cheap aftershave and run the system - the smelliest room has a leaker!

Nozzle

 

[dreadnoughtheating]

My plumber offered a good hint for trying to track down a leak - chuck in a bit of cheap aftershave and run the system - the smelliest room has a leaker!

Nozzle

Hai karate or Brut45?, should have matured nicely lurking in a wardrobe somewhere?

DH