DIY Doctor UK DIY Forums

I posted this question about 18 months ago and had many helpful replies,thank you all.

Shortly after installation I noticed the boiler pressure was rising slowly(it got to 3 Bar).After bleeding the rads.(it's only the two u/stairs ones which need bleeding)the pressure dropped,as expected, but then started creeping up again,bleeding the rads led to a pressure drop,then a pressure increase etc.
I contacted the installer who scratched his head and avised me to call Ideal
I telephoned Ideal,they sent an engineer.
Over a week,at first disconnecting the old filling loop which had been left in, then changing one part at a time,he changed the heat exchanger,the expansion vessel? - and the pressure gauge.
This hasn't cured the problem.Over time,during which the boiler has been serviced, I've monitored the pressure and as the pressure rises I've bled the rads which reduces the pressure,I've done this about once a month. This last time the pressure gauge dropped to zero and the boiler shut down - advising me to re-pressure the system or call an engineer.As an experiment I did neither, but waited,after 5 hrs.the boiler had self pressured up to 1Bar !

Before I contact Ideal Standard again can anyone give me some idea what might be happening?

ps.the filling loop on the boiler is not left connected so that can't be the problem

Hi, as the filling loop is not connected that removes first thought!!
I wonder if you have a conventional system with a hot water storage tank ie not a combi? if so most likely thing would be a pinhole in the heating coil inside tank allowing mains pressure from hot water to get back into heating system pipework,
You don't say what the set up is so not much to go on,
regards

Hi "sparks"
Thanks for your reply,sorry it's taken so long to get back to you.

The installation is a conventional combi boiler- no hot water storage tank nor header tank.The filling loop is disconected(the old one from the previous boiler was disconected on installation of the new boiler)

The expansion vessle has been changed as has the heat exchanger and even the pressure gauge.

We have recently been away for a week - on return I found the pressure had increased from 1b to 2b even though the boiler had not been in use