Potterton Promax 24HE problems....

floss2

We had a Potterton Promax 24HE (aka Baxi Bermuda) fitted Feb 2003 by British Gas, and took out their central heating service & repair cover. In Oct 2006 we had our first call out, then it was OK until Feb 2008. October 2008 we had 2 more callouts, March-April 2009 we had 7 and the boiler was virtually rebuilt from the inside out. We had a further 2 call outs in January this year, and yesterday had our 4th in 2 weeks.

The problem is always an inability to fire followed by lock-out. It also makes a loud bang when it does ignite, which I presume is gas build-up. It's also arcing inside the case when trying to light, which I presume is not helping the ignite/small explosion scenario! Tomorrow we are due to have a new ignition cable & insulation fitted which I am told should rectify this ingition issue.

However, yesterday I discovered from the BG engineer that the gas pressure at the boiler inlet is only 15 mB, yet at the meter it is 22 mB. The boiler was fitted by BG, to existing pipework that is not 22mm. He is requesting a new governor for the meter to be fitted tomorrow, FOC by Transco, and thinks that may resolve the problem.

Is he right to think this, and could the low inlet pressure be contributing to the problems we have had? And what is the likelihood of BG rectifying the problem with new pipework, or replacing the boiler as they do not appear to be able to repair it?

gas4you

If you have 22mbar at the meter already, then a new govenor is not going to help one little bit.

Your problem is that it has never been installed properly.

Your gas pipe work is way undersized as you should only have a maximum of 1mbar drop across the carcass to any gas appliance when the are ALL running.

With your 7 mbar drop I would class this as At Risk and turn it off especially if you also have a gas cooker or hob.

Report BG to Gas Safe for an illegal installation, then get BG to replace the gas pipe to the correct worked out size.

floss2

gas4you wrote: »

If you have 22mbar at the meter already, then a new govenor is not going to help one little bit.

Your problem is that it has never been installed properly.

Your gas pipe work is way undersized as you should only have a maximum of 1mbar drop across the carcass to any gas appliance when the are ALL running.

With your 7 mbar drop I would class this as At Risk and turn it off especially if you also have a gas cooker or hob.

Report BG to Gas Safe for an illegal installation, then get BG to replace the gas pipe to the correct worked out size.

This isn't as easy as you imply - the work was done in 2003, not within 6 months as the Gas Safe website says.

gas4you

Who cares when it was installed. It is still an illegal installation due to the pressure drop between meter and appliance. End of.

ollski

Your 7mb drop could be due to a blockage / restriction in the pipe in the last 7 years. It won't be the cause of your problem either.

floss2

Yesterday's visit from BG resulted in the boiler being isolated as it is unsafe - the explosions we have been experiencing appear to be backfiring of exhaust gases.....

Tomorrow's visit should bring the engineer and his area manager to decide the verdict.

Am not sure how we could have got a restriction / blockage over the last 7 years, nothing has been added / removed / no work done in the house to affect the gas pipework....

ollski

What happens on these is that the faulty electrodes tend to cause explosive ignition in the boiler which causes the red seal on the front combustion panel to fail. If this continues without being remedied the seal between the sump and the combustion box fails aswell, causes a strong gas smell from the flue and lots of ignition lockouts.

floss2

BG engineer been today, has been supplied with 2 pcb boards which are both faulty, now waiting for Potterton engineer to come out on Thursday.

ollski

Bet you 2 pcbs aren't faulty unless they broke them, that's clutching at straws.
Blockages in gas pipes can be caused by dust and debris blocking the gas valve inlet filter over time, especially if nat. grid have been working on the mains.

floss2

ollski wrote: »

Bet you 2 pcbs aren't faulty unless they broke them, that's clutching at straws...

There are no straws to clutch - both boards have been acknowledged as part of a faulty batch by Interpart & recalled.

TBH BG are now stumped, boiler has been rebuilt from inside out (some parts twice over), they are paying for Potterton visit not us.