Potterton Powermax HE85 query

[ianosull]

Our boiler keeps locking out with the code A15 showing on display, indicating pressure loss. Having topped up the pressure with the filling loop I watched the boiler for hours and have found the following happens:
When CH comes on, it heats up and pressure increases as expected, then pressure continues to increase to around 3.2 bar on display and manual gauge and the pressure release valve operates which cause it to drop to around 2.8 bar. The heating then continues to work, maintaining this pressure until it switches off at which point the pressure drops as the temperature cools. This in turn drops so much that the boiler locks out, and i understand that this is because of the water loss through the pressure releif valve - which is not dripping until 3.0 bar is attained.
I have gone through the full commisioning instructions and followed them to the letter with regard to draining water until it runs air-free, bled the rads, checked the expansion vessel pressure with no system pressure- 1.1 bar etc, but with no success to curing this fault.

Sorry for the long winded nature of this but any advice from anyone would be greatly appreciated

Many thanks, Ian

 

[stevetheplumber]

Our boiler keeps locking out with the code A15 showing on display, indicating pressure loss. Having topped up the pressure with the filling loop I watched the boiler for hours and have found the following happens:
When CH comes on, it heats up and pressure increases as expected, then pressure continues to increase to around 3.2 bar on display and manual gauge and the pressure release valve operates which cause it to drop to around 2.8 bar. The heating then continues to work, maintaining this pressure until it switches off at which point the pressure drops as the temperature cools. This in turn drops so much that the boiler locks out, and i understand that this is because of the water loss through the pressure releif valve - which is not dripping until 3.0 bar is attained.
I have gone through the full commisioning instructions and followed them to the letter with regard to draining water until it runs air-free, bled the rads, checked the expansion vessel pressure with no system pressure- 1.1 bar etc, but with no success to curing this fault.

Sorry for the long winded nature of this but any advice from anyone would be greatly appreciated

Many thanks, Ian

sounds like you need to check the preasure in the preasure vessel which is done from the shradervalve on it and replenished with a foot pump or compressor boier has to empty to do it

 

[ianosull]

Hi steve, thanks for reply. I know that the expansion vessel can lose pressure, but I had checked it with no water pressure in system. That is what is strange, and I am no wat my wits end!!!

 

[LIFES A GAS]

Hi Ian, I would suspect that the pipe that conects the expansion vessel is maybe blocked, this would stop the expansion vessel from doing its job, as the temprature rises there should be very little increase in system pressure if it working OK, had this problem a few times with Glow Worm ci and found that the flexi hose connecting expansion vessel to pump housing had a internal bore of only a couple mils and was easely blocked by sediment, worth looking at as maybe the same on your Powermax I think I had this problem with one of them a couple of years ago.
Hope this helps, Martin

 

[ianosull]

Hi Martin, thanks for the advice. Checked that pipe and found a slight kink in it which appears to have trapped a small amount of sediment from system. Sorted that out, now works a treat! Now just have to flush etc and refill!

Many thanks