Every boiler change has a gas side, and this photograph is where it starts.
That is a gas meter in a cupboard on one of our jobs. The regulator with the blue cap sits on the incoming pipe, the two flexible connections run in and out of the top of the meter, and the green and yellow cables clamped to the pipework are the earth bonding. Everything a boiler burns comes through a cupboard like this first, and the pipe that leaves it has to reach the boiler big enough to carry what the boiler asks for.
Why the pipe matters
A new boiler is very often bigger, in gas terms, than the one it replaces. A combi heats hot water as the tap runs, so when somebody is in the shower it burns gas at its full rate, and that rate is usually higher than an old boiler that only ever heated a cylinder. The pipe between the meter and the boiler has to carry that much gas and still have the pressure up when it arrives. Gas loses pressure along a pipe the way water does, more over a long run, more round every bend and fitting, and more in a narrow pipe than a wide one, and a boiler starved at the end of an undersized run cannot do what it was bought to do. So on a boiler change we do not assume the old pipe will feed the new boiler because it fed the old one. We look at the size of the pipe, the length of the run and the bends in it against what the new boiler needs, and once the boiler is in we check the pressure with it running flat out, at the boiler as well as at the meter. If the two are too far apart the pipe is too small, and the fix is a bigger pipe, not a hopeful one.
15mm or 22mm
People ask whether every new boiler needs a 22mm gas pipe. It does not.
It depends on how much gas the boiler burns at full rate and how long and twisty the run to it is. A short run in 15mm can feed a smaller boiler without trouble. A combi at the far end of the house is a different matter, and on plenty of changes the answer is a new run in 22mm.
Part of the whole job
Our boiler page says a replacement is the whole job or it is not worth doing, and the gas run is part of that, alongside the flush, the filter and the controls. The combi installation on a bare wall shows the other end of the same kind of job, the boiler and its pipework once it is on the wall.
A boiler change
Ring 07546 185778 if your boiler is due for replacing. We look at the gas side as well as the boiler, and you get it in writing before anything is agreed.
