Boiler pressure loss after service

[Gorners]

Had the annual service on my WB Greenstar 37CDI last week, working fo ebut just decided to check the pressure last Thursday and noticed it at zero.

After some investigation the pressure is going into the red and expanding out of the PRV, I've had this issue before so I know this should be easily remedied by sorting the expansion vessel.

My worry is that I also think the condensate pipe is drilping when not in use, about 1 drop per minute. It's hard to keep a constant eye on this over a long period of time with the heating on all the time at this time of year, but it definitely drips for a while after the boiler has stopped. Can the PRV problem and this dripping be related?

Is there anything a heating engineer does in a service that could cause a small leak? Or am I just being extremely unlucky that the expansion vessel and possible heat exchanger has gone

 

[dilalio]

Only procedures and monitoring can give you the answer.

Check/recharge vessel with water side open to atmosphere. Recharge pressure to system and monitor for loss per hour/day/week. Clear plastic bag over discharge and over condensate outlet (when boiler is off).
Engineer may have used PRV to let pressure out of system - which he shouldn’t as they are prone to letting by when activated... plastic bag will prove if this is passing.
If system can be left off for a few hours and water is coming out of condensate then maybe there is an issue with the hex!

 

[Gorners]

Thanks for the reply. I'm certain the PRV Is the primary cause of the pressure loss as I've seen the water dripping out and the pressure gauge in the red.

So does the condensate still let out water after the boiler has stopped running for a while? I thought it should only run when heating or hot water running however if you're saying check after a few hours then I guess that's not the case? And if so I think I can relax!

 

[dilalio]

Any pipe that’s had water flow through it can drip for a while. Condensate run can hold this and a low fall might mean it takes a while to drip out. Repressurise the system and while it’s still off check the condensate and see if the drip becomes more frequent. Can you confirm that you have separate condense and discharge pipes.

 

[Gorners]

I've got one valve on the outside wall which is the PRV, and a pipe which runs outside into a drain which I assume is the condensate pipe.

 

[Gorners]

Ok, heating off for 3 hours, drop has slowed right down to about a drop every 3 minutes, but it's still there. Repressurised which didn't make it go any faster. I'll try and take a pressure reading overnight to see if it drops, that will give a clearer indication I guess.

 

[ianmcd]

PRV should be in copper and condensate will be PE

 

[Gorners]

PRV should be in copper and condensate will be PE

That's right.

 

[wig]

what fault does water collected in a bag over condensate pipe when boiler switched off indicate?

 

[Hot&Cold]

out of interest,who serviced your boiler ?

An independent or a national company

 

[Gorners]

what fault does water collected in a bag over condensate pipe when boiler switched off indicate?

As far as I understand, a pinholed HEX and not much else.

 

[Gorners]

out of interest,who serviced your boiler ?

An independent or a national company

Was an independent. He's ordering a new expansion vessel to fit and will check condensate pipe when he fits it.

 

[Madrab]

As far as I understand, a pinholed HEX and not much else.

Nope ... it could also mean that the PRV could have been lifted to test it and they tend not to seat back down again properly. Some older MI's ask that when a boiler is serviced the PRV is activated to ensure it's working but experience has shown us that doing that can cause a PRV to let by and it then needs to be replaced.

 

[wig]

What's a HEX?

 

[wig]

Nope ... it could also mean that the PRV could have been lifted to test it and they tend not to seat back down again properly. Some older MI's ask that when a boiler is serviced the PRV is activated to ensure it's working but experience has shown us that doing that can cause a PRV to let by and it then needs to be replaced.

Thought a PRV only leaks through the copper overflow?