15mm upgraded to 22mm for Vaillant Combi

v20law

Hi - we are keen to get a combi installed and after much deliberation and help from this site (thank you), we are going for a Vaillant. I thought we'd cracked it when we decided on the Vaillant 837 plus which is an extra £100 on the 831 quote ( quoted £2800 for the 831 model) but now the plumber needs to come back out cos' the 837 needs an inlet of 22mm not 15mm.

I think we have an inlet of 15mm - anyone got any idea what work is involved to increase the inlet and the cost? I want to go in with my eyes wide open when he comes round!! Thank you.

adaze

I'd imagine a fair bit, though it depends on your current setup. If you are on 15mm at the moment chances are this is 15mm from where the water enters your house, so to get 22mm to the boiler he would need to remove all the 15mm from where the water comes in to the boiler. And that could be a lot of pipework that may already be hidden away. I am assuming that you mean the CW inlet?

adaze

... Just thought you might mean inlet for the gas, and we had to have this done, basically the plumber went back to the meter and took a 22mm feed from here and ran this all the way to the boiler, was a fair bit of work but we were having other work done so could hide the pipework. It is possible to just go along the outside of the building to cut down on mess etc...

Razor

Depending on the length of the run, how many bends are in it and what other appliances it serves you may well find that part of it needs to be in 28mm, ask the corgi registered engineer (not plumber) to show you the pipesizing calculations that he will need to make