I have a Baxi Platinum 33kw boiler installed pressured up by a mains feed to 2.0 bar. When the central heating is switched on the pressure in the boiler approaches 3.0 bar and the PRV releases water through the pressure release pipe outside.When the boiler has switched off and cooled several hours later, the pressure remains high at 2.7 bar.... no PRV release. Again, when switched back on it goes back up and releases again.The filling loop remains in place but is isolated and has been checked that is is working ok.Every so often, the boiler cuts out and shows a low pressure warning as after a couple of weaks the pressure drops to 1.2 bar.Any ideas what the problem could be becuase i'm baffled. How can the system maintain 2.8 bar when cool? All radiators get hot with no cold spots.Thanks
Shut off the make up water supply valve and release the pressure manually by opening the PRV by hand after the boiler is cool. If the pressure drops, there was air in the boiler. If not, the gauge is out of caliibration. Don't forget to take static head into consideration.
