Potterton Puma 80 - low pressure repeated problem

Hi,

I'm new here but tried to search for this problem first with no luck.

I have recently moved into a house with a Potterton Puma 80 combi boiler and on several occasions the 'low system pressure' light has come on and prevented the system from working and meaning no central heating in this cold weather.

I have found a manual on the internet and located the tap on the top of the boiler to top up the pressure and this works temporarily until the heating is on timed and off for any period of time then the light comes back on and the pressure gauge drops into the red and it shuts down.

The time between the warning light coming on is getting shorter, started a few days apart but now it doesn't even stay pressurized over night. Are there any common problems with the boiler or components which may be faulty causing this problem?

Thanks for reading this and look forward to your suggestions to keep us warm

low pressure = leak check prv and all radiators

There are no obvious leaks from any of the radiators, would the next step be to change to prv then?

Am i right in assuming prv is pressure release valve in the boiler??

Yes, but check it first. When the System is hot, check the pressure please.
Never assume anything. It makes an ASS outta U & ME. Corny but true.

Scott.

you need to check if there is water leaking out of the prv and any othe robvious leaks

IF the prv needs to be replaced ,then you need to also check the pressure in the expansion vessel,if you look FAQ section there will be write up on how to re pressurise it

Thanks for your replies so far, I have double checked and there are no radiators leaking. I have placed a bottle under the overflow pipe from the boiler and the pressure release valve and yes it is letting out water.

I have re-pressurised the boiler to 1 bar and this was when the boiler was cold and not firing. I have then switched on the heating and the pressure according to the pressure gauge goes up to over 3 bar!

Once over 3 bar the prv does let some water out to lower the pressure to under 3 bar. Then when the boiler is switched off it cools down the pressure is in the red and the low pressure warning light illuminates again.

Any ideas why such a big difference in the water pressure from when central heating is off to when on? Surely this is not normal and the difference should be less, does this indicate some other fault rather than the prv?

you have been told twice before

check FAQS for advice on how to re charge the boilers inbuilt expansion vessel, this has failed , that is why the pressure is rising to 3 bar

I have now found the FAQ section and located the guide for re-pressurizing the expansion vessel, thanks for your replies.

Shame about the unhelpful attitude of the last poster though