Why Do New Boilers Need A 22mm Supply?
- Thread starter nashville
- Start date
Sponsored Links
Coz the manufacturer says so 
Sponsored Links
To meet regulations you are only allowed a 1mBar pressure drop between the gas meter and the appliance.
The more powerful the appliance the more gas it is trying to draw from the supply, hence the pipe size has to increase with the more gas being used.
Some may need even larger pipes than 22mm.
The more powerful the appliance the more gas it is trying to draw from the supply, hence the pipe size has to increase with the more gas being used.
Some may need even larger pipes than 22mm.
I want one of them pots
thats a bit like asking why a motorway has 4 lanes.
lets just put a 35mm gas pipe in be safe.
lets just put a 35mm gas pipe in be safe.
New boilers do not necessarily need a 22mm supply. Some commercial burners have a 15mm inlet.
The size of the gas supply pipe is worked out on the basis of the flow and pressure drop from the pipe resistance, at the volume needed to sustain the appliance.
Therefore there is no blanket size, it depends what you are fitting and where you are fitting it. Calculation is involved here.
And finally, in the case of a few manufacturers, it depends on what their stated minimum inlet size is (such as Worcester Bosch, but strangely not Buderus Bosch, in the UK).
The size of the gas supply pipe is worked out on the basis of the flow and pressure drop from the pipe resistance, at the volume needed to sustain the appliance.
Therefore there is no blanket size, it depends what you are fitting and where you are fitting it. Calculation is involved here.
And finally, in the case of a few manufacturers, it depends on what their stated minimum inlet size is (such as Worcester Bosch, but strangely not Buderus Bosch, in the UK).
I just fitted my first vaillant 438 this week, which only has a 15 mm inlet, which struck me as odd.
The manufacturers keep the price of their boilers down by using very small gas pipes internally. Nevertheless their boilers still need the minimum gas pressure and pipe resistance at the inlet connection.
Boilers over 24 kW usually need a pipe size greater than 22 mm unless the gas meter is within a few metres.
Tony
I have never fitted a 438 as yet, but I too find this strange, as the 837 and the 637 both have 22mm tails for the gas.
You probably had a Worcester Bosch 24ri fitted and the installer only fits Worcesters.
Therefore he would have unquestioningly followed their instructions, and you paid for a new pipe that you probably didn't need.
Therefore he would have unquestioningly followed their instructions, and you paid for a new pipe that you probably didn't need.
DIYnot Local
Staff member
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.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
