slow pressure loss vailliant turbo max plus

[domo]

Hopefully someone can offer best course of action!
have slow pressure loss of approx 0.5 bar over 1 week on the title boiler above.

Have british gas homecare and they have now visited 3 times without finding cause of problem.
first two visits they just re-charged expansion vessel and re-filled,pressure holds for 24-36 hours boosting nicely when c.h is on at first until pressure starts to drop slowly.
on third visit some leak sealer was added to system which made no difference.

have checked all visible pipes and fittings and no leaks found,ground floor pipes are wrapped but are in screed,but no visible wet patches but i appreciate that if a leak,then it is small.

just wondered on best advice for solving this leak or possible causes?
Just dont feel that reassured that boiler is being checked correctly and currently no parts have been changed.boiler is now fitted with external expansion vessel as internal one failed about 2 years ago.boiler is approx 10 to 12 years old.dont want to start chopping screed if possible fault with boiler/expansion vessel,i do appreciate that this will be hard to locate?

Dom

 

[Last Plumber]

With all due respect to you, At the rate BG charge for homecare I would either insist they find it or Cancel the homecare and employ a recomended Heating Engineer

 

[Darren Jackson]

Could be that the system is in need of a cleanse and a power flush. There could be an hydrogen build up causing the pressure to drop.

 

[tamz]

Get them back. Thats what you are paying for
In the meantime if you like
There should be a pipe with a couple of bends back to the wall outside through the wall from the boiler. Find it and stick a balloon or tape a bag on the end and check it in a couple of days

 

[domo]

With all due respect to you, At the rate BG charge for homecare I would either insist they find it or Cancel the homecare and employ a recomended Heating Engineer

Yes i aim to do this but wanted to gain some probable causes to suggest to them and recommend they send someone who knows what they are doing!

 

[domo]

Get them back. Thats what you are paying for
In the meantime if you like
There should be a pipe with a couple of bends back to the wall outside through the wall from the boiler. Find it and stick a balloon or tape a bag on the end and check it in a couple of days

Yes have already tested this and prv seems sound and not letting by

 

[ShaunCorbs]

Yes i aim to do this but wanted to gain some probable causes to suggest to them and recommend they send someone who knows what they are doing!

its simple really either leak inside boiler or under floor

 

[domo]

Could be that the system is in need of a cleanse and a power flush. There could be an hydrogen build up causing the pressure to drop.

would there be any other symptoms of this as heating appears to be functioning correctly with no air in rads or cold spots?
heating also appears to warm up quickly with no loss of performance?

 

[Last Plumber]

You need to ask them to test to identify whether it is the system or boiler that is loosing.

That is always a good place to start

 

[tamz]

Next time you ring them demand a visit from a lead engineer as you are fed up with numpties

 

[domo]

ok so re-visit booked for monday and insisted on senior engr!!

also can anyone tell me if the expansion vessel would lose its pressure if a small leak is present as boosts well for a day after re-pressurizing and then the pressure does not go up much after that when heating comes on?

 

[domo]

With all due respect to you, At the rate BG charge for homecare I would either insist they find it or Cancel the homecare and employ a recomended Heating Engineer

I agree but finding a recommended heating engr in my neck of the woods is not easy!
and appears that alot of posts on here seem to be north of my border:rolleyes2:

 

[Billy Bob Bob]

ok so re-visit booked for monday and insisted on senior engr!!

also can anyone tell me if the expansion vessel would lose its pressure if a small leak is present as boosts well for a day after re-pressurizing and then the pressure does not go up much after that when heating comes on?

tell him to check the diverter valve carefully ,they leak in the middle