I am about to have a new Combi fitted (Worcester Bosch 30cdi). The installer and I cannot see the existing gas pipe to the current Worcester Highflow Heatslave so are not sure if it is 22mm or smaller. (obviously we will see it when the boiler is removed)
A neighbour in the same type of house found when his Heatslave was replaced that the pipe was only 15mm and had to have a new (ugly external) 22 pipe run installed. This neighbour never had much success with his Heatslave - but mine has always performed well and has been inspected every year by B Gas.
I told the installer I was concerned that the pipe could be 15mm so he offered to perform some sort of drop check. He took a reading at the meter with a manometer with the gas cooker and boiler running - he then repeated the test at the boiler and phoned Worcester Bosch. They confirmed that the pressure was acceptable. I think the drop was 2 milli-bar. (from 21 down to
19)I realise there is some risk and uncertainly and that I may have to run a new 22mm pipe - but what do you think. Does the 'evidence' point to the hidden pipe being 22mm - or is this irrelevant because the pressure is okay?
Do you think the installers approach is reasonable?