Potterton Promax 28HE+

[polo1]

Hi guys, can I pick your brains? The above boiler was installed in my mother's house about four weeks ago. She calls me to say the heating isn't working. Go down to see the fault code (118/9?) for low pressure, and sure enough the gauge is at <0.5 Bar and no heating/hot water. The filling loop hadn't been connected and I didn't have tools to loosen the end caps to allow me to fit the loop. So, I go back tonight and find that the heating is working. The pressure gauge is reading just >1Bar. So before I contact the installer, how can the pressure recharge in the way it appears to have and second, is it normal/correct that the boiler can reset itself after locking out due to low pressure? Thanks!

 

[Poxi]

Its called expansion..You need to top the pressure up to 1.5bar when the boiler is COLD. (True pressure reading)

 

[polo1]

Thanks, but I still don't understand, when the boiler has locked out due to low pressure and is stone cold, how the pressure can then increase enough to allow the boiler to fire again! To be clear, I'm not looking to sort the problem myself, the company who installed it can do that, but I just like to understand how/why problems occur and what the solutions might be:book: