Anyone know why a plumber would tell me that the pipes that run from my gas mains/meter to my boiler need to be changed to 22mm (they're currently 15mm)? These are gas pipes, not water pipes. We're having a new boiler and shower installed, hence the reason for the works. I thought maybe that all new boilers (ours has got to be 15 years old) may only take 22mm pipes, but then why not leave the existing pipes in place and attached a 15/22mm adaptor at the boiler end instead of having all the floor boards up to replce the 8 or 9 metre's of pipe we have.
15mm from the meter has never been acceptable, regs stated 22mm to within 1 metre of appliance.
Basically you have know about pipes, sizes, appliance gas rates etc - it's not as simple as just connecting up.
If incorrect pipe size is used - if you have a gas fire, oven or hob and the boiler comes on, the other appliances could be starved of gas. When the boiler goes off - the gas is back at hob/fire etc but not lit - extremely dangerous.
22mm is the minimum size of any gas pipe from the meter, longer runs/more appliances 28mm and so on.
Thanks for your reply and the info. I understand the concept of what you're saying, about one appliance being starved of gas when another one is switched on if the pipes are not big enough. What i dont understand though is that the current set up (15mm pipes from mains) has been in place for years and years (proberly about 15 years). We are not adding any additional appliances, so the demand on the gas supply will remain the same. All we're doing is having a new boiler put in, so I dont understand why the pipe work thats in place now and has been for years needs to be made bigger.
so I dont understand why the pipe work thats in place now and has been for years needs to be made bigger.
Because it doesn't meet todays regulations or adhere to manufacturers instructions - simple as that.
Just because it's been like that without problems for years is irrelevant. It may have worked - but not efficiently. Your new boiler will be a condensing boiler - the only way it'll work efficiently is if the gas supply is correct.