Boiler pressure dropping

[Emnick]

Good evening all ,
Our boiler constantly loses pressure and needs topping up weekly or hot water goes off etc, the boiler has been replaced and the pressure still drops the same,
There is no obvious sign of leak anywhere so a bit lost what to do ,
A plumber has put a leak fix substance down the pipes but didn’t seem to have made a difference- any advice much appreciated

 

[Last Plumber]

What kind of boiler do you have?

 

[SimonG]

It doesn't take a lot of water loss to cause a pressure drop. Have you checked all radiator valves for any signs of dampness? Are there any damp patches on ceilings?
Do you have pipework under floors downstairs? Are they timber or concrete?
Although it's a new boiler have you isolated the boiler from the system to identify whether it's a system issue or boiler issue?
If it's a combi I wouldn't want to be chucking leak sealer in.
Leak needs to be found and repaired or bypassed by re piping if it's in a concrete floor.