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Oct 10, 2021
2
0
1
MANCHESTER
Member Type
DIY or Homeowner
Hoping someone can help. Moved in to our new house a week ago. The boiler is a Potterton Promax Combi 28 HE. Discovered it was losing pressure overnight and we'd get the E119 message and no heating or hot water until we repressurised.
Checked all radiators and discovered a few small leaks which have been fixed. Checked under floorboards and discovered a large leak which again has been fixed. Been around whole system and radiators again and now confident there are no leaks. But boiler still losing pressure.
A plumber has replaced the PRV and confirmed no water escaping from overflow pipe.
Today we have isolated the boiler by turning the valves to separate it from the central heating system.
When hot water was called for the pressure gauge rapidly drops by 0.5 bar then recovers a little when hot water is shut off but not all the way back to its previous level.
In the 8 hours since we isolated the boiler from the central heating the pressure has dropped from 2.5 to 1 bar and we now have the E119 message again (at 1 bar).
Does this sound like a faulty diverter valve? If not, does anyone have any ideas??
 
your boiler should not show e119 at 1bar for a start, gauge at fault, and have you also checked the expansion vessel.
 
I think I’d be suspecting the pressure sensor too. If it’s losing pressure whilst the boiler is isolated it’s obviously at the boiler.
 

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