Depends on length of pipe run, and number of elbows or bends,
as rule of thumb pipe size should NEVER be less than the boiler inlet connection, you will need to consult a gas engineer to survey and deign and install the pipe work
Thank you for responding. The reason I ask is that I have had two gas engineers look at the job , and one says 15 is ok, and the other says 22 will be needed!!
I think I've got it sussed. It's not really exact science, but the 22 needs to go to within 1 metre of the boiler if the boiler is not bigger than 15Kw or 25Kw. That SHOULD be ok but a test would need to prove it, and 22 put in if 15 was inadequate.
10mm should do it .. its cheaper
you may as well save money on material cause you dont have value for life if your doing it yourself.
GET A GAS INSTALLER/ENGINEER
sorry mis-read the post a enigneer who knows what he is doing
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local