Combi losing pressure

[Simon Hill]

Hi
I have a Combi boiler that keeps losing pressure. I top up, up to 1.5, but this drops within 6 hours and the system switches off.
We have looked everywhere and cannot see a leak. I have used the Fernox F4 leak sealer, but this hasn't helped.
Any ideas?
(Yes I have had a Gas Safe Engineer out before you post that)

 

[Harvest Fields]

Hi
I have a Combi boiler that keeps losing pressure. I top up, up to 1.5, but this drops within 6 hours and the system switches off.
We have looked everywhere and cannot see a leak. I have used the Fernox F4 leak sealer, but this hasn't helped.
Any ideas?
(Yes I have had a Gas Safe Engineer out before you post that)

Then I would get him back out. As it is clearly not fixed and you have looked at the external parts of the system. It maybe within the boiler? Is the copper pipe outside dripping?

 

[Simon Hill]

No, no problems with the pressure release
He suggested the leak seal, so I've tried that. Was just looking for advise before getting him back out.

 

[Scott_D]

What boiler?
Top up the pressure
Turn off the power to the boiler
Shut the flow and return valves
If the boiler looses pressure it's the boiler
If the system looses pressure it's the system.

 

[Simon Hill]

Perfect, thank you. I'll give that a go

 

[neil grimes]

Hi,
please can you offer me some advice. I have a greenstar 37CDi boiler losing pressure. I charged to 1.5 barg and closed flow and return 90 degree boiler valves to shut position. Overnight the pressure had dropped to zero by the morning. I have already fitted a new expansion vessel and checked bladder pressure is still OK with no water on bladder side. I have left a container under the pressure relief valve and observed no water over 24 hrs leaking from it. Any other ideas for me to check?

 

[Harvest Fields]

Are you Gas Safe Registered mate?

 

[neil grimes]

Hi,
im not gas registered, this id my own boiler. I thought i had a leaking pipes but not sure now after checking the boiler last night.

 

[Harvest Fields]

Hi,
im not gas registered, this id my own boiler. I thought i had a leaking pipes but not sure now after checking the boiler last night.

I would get a Gas Safe in mate. You shouldn’t be taking the case off your boiler.

 

[daWilko]

Yes - no playing with the boiler or its controls please. I had a couple of slow leaks that were in the CH plastic distribution pipes to ground floor rads at home. The rising connection to the rad was copper but there was a transition to plastic (90 deg elbow) in the concrete. Weep weep, ho hum. My first step was to put in valves to isolate the rads one at a time and locate the leak.