L
lame plumber

You let your old camray 5 non condensing flue warm the single skinned plastic tank, as the single skin allows for a quicker heat transfer than a bunded one would :bomb2:
still the explosive ignition problem became clear once I extracted the lowest baffle

and changed the nozzle and started setting it all up, first drop the pump pressure from 150 psi to 115psi!!, then shut down the
air inlet from 10 to around 2 to get the CO2 back to 11 fm 14.
Obviously the customer admitted the boiler hadnt been serviced for a bit!!!!!!!!!, but hey ho it took 3 & 1/2 hours to scrape out the soot and get it looking normal, but the scary bang on start up had gone!, so they couldnt tell whether the boiler had come on anymore. And the last advice given was prehaps they ought to have a flue guard put over the flue to stop the toddlers putting their little hands anywhere near it. Still a great little earner and I still have to go back and swap that baffle that is sitting further up in the boiler now. Happy xmas to all the gas engineers out there you just dont know what your missing.