Gas pipe for boiler?

[goooba769]

Just a quick question do the new type of condensing boilers need 22mm gas pipe as my old boiler looks to be 15mm coming out of the wall. The house is 1980ish so maybe there is a 22mm pipe under the floorboards.
Another question the gas box is sunk into the house wall and the pipe looks to be run in the cavity how do they run a new 22mm pipe if I need to to the boiler in the back of the house and any rough idea on cost????

 

[noonespecial]

I've seen boiler installations with 200mm gas supplies to them - it depends on the boiler type and size. You probably wont need 200mm gas pipes though

Check in installation instructions - these may say a minimum of 22mm up to within so many metres of boiler - if so that is a minimum requirements. The only way to determine it is by calculation / charts.

Normally the connection to a domestic boiler is 15mm gas.

Gas pipe should not run through cavity unless it is sleeved.

You can run a new gas supply to the back possibly by burying it in the ground or surface mounted on a wall.

You need to call in a CORGI registered person to give you advice on all these matters. Don't attempt any of it yourself as by the questions you are raising you would not be considered by the HSE as competent to do so.