Another Potterton Puma 80e request for help

[Etch]

Hello all

I am a keen reader of these forum and have picked up a few tips that have saved me a lot of money in the past.

I have recently developed a problem with my boiler. A week ago, the radiator was coolish and i decided to bleed it. It let out a lot of air and naturally the boiler low pressure valve tripped. I repressurised the system and turned on the unit.

The machine fired up fine and the pressure rose from 1.5 bar to 3 bar (red line). The heating sits at this until it is timed to go off, then over night the pressure drops again to below 1 bar and the low pressure light comes on. I have then got to repressure the system again.

I thought prehaps the pressure relief valve had not shut properly as I notice some water coming out the waste pipe (not a flow but some slight drips) so i opened it up to try adn wash any debris, but this does not seem to have solved it.

Someone suggested checking the pressure vessels pressure via the valve at the top but not sure what this should be.

I would appreciate any thoughts. I dont think i have a leak as i cannot see any water (its been about 1 week ) and it runs fine when heating is on.

 

[Gasguru]

Read the FAQs on expansion vessels and then replace the safety valve.

 

[ChrisR]

See Boiler Pressure Problems, in the FAQs.

 

[Etch]

Thanks guys for the quick repsonse. Can i ask for clarification of a couple of things.

When repressuring, I let the pressure gague drop to 0. Then repressurise the system to 1 bar cold.

The bit im stumped at, is when repressurising, i have to allow the air and water to escape.

In our systems there is no drain cock outside ( i have looked, the plumber has loked but cant see it. Can i let the air and water escape by simply leaving a radiator bleed valve open?

Do i also drain the water in the expansion tank via the presure reflef valve?

Thanks once again for any help. It is greatly appreciated.