Why size of gas pipe?

[stratobuddy]

My boiler needs 22mm pipe from the meter, this I understand.

So why is the gas connection on the boiler only 15mm, needing an adapter from 22mm to 15mm close to the boiler.

Why isn't the boiler connection 22mm?

[Simon F]

if the manufacturer has made the gas connection 15mm then that's sufficient for connection to the boiler.

its all to do with resistance from the pipe walls affecting the flow of gas, which is very low pressure (19-23mbar )
the longer the run of pipe the bigger pipe size needed to compensate.
so the fact that the connection at the boiler is 15mm does not mean that 15mm would be acceptable for the complete run.

gas is not water which would be fine in 15mm due to a pressure probably 100-200 times higher!

[stratobuddy]

Thanks for the above, but wouldn't it be easier for the installer if the boiler connection was also 22mm so the pipe could be connected straight in?

[Simon F]

some boilers particularly combi's do have a 22mm connection for the gas,
its no great challenge to fit a reducer on the last stretch of pipe

depending on the length of pipe and what its supplying could need to come from the meter in 28mm even 35mm and then be teed of to whatever appliances or reduced down as needed

[tamz]

My boiler needs 22mm pipe from the meter, this I understand.

So why is the gas connection on the boiler only 15mm, needing an adapter from 22mm to 15mm close to the boiler.

Why isn't the boiler connection 22mm?

Why does your gas hob come with a 15mm connection when the size of the burner jet is smaller than a pin hole?

[Koogatubac]

Haha Newer boilers require bigger size gas pipe,

Older boilers werent as big in demand for gas, therefore alot have been on 15mm.

Nowadays its good practice to come off the gas meter in 28mm (all depends how far the boiler is and how many appliances is going to be run off it.)

Just as those guys above have mentioned

[REDSAW]

Why does your gas hob come with a 15mm connection when the size of the burner jet is smaller than a pin hole?

why does a duck spend most of its time with its head and mouth under water when there is a smaller hole in the rear, can they mimic a wave runner?........!...............

[AWheating]

the appliances connection has no bearing on the size of the pipework required to supply the gas to it. The gas pipe is sized on a number of factors like route and length of pipe run, appliance size/rate, type of material use ect.....

[kirkgas]

Thanks for the above, but wouldn't it be easier for the installer if the boiler connection was also 22mm so the pipe could be connected straight in?

who says the boiler needs 22mm for every install? if it has a 115mm connection there will be situations where 15mm is adequate, in different houses with different layouts 22/28/35 might be needed, as others have said some have a 22mm connection so they need

[peteheat]

The real answer to your question is available after serving a five year apprenticeship, working on gas for a few years then proving competence by completing never ending expensive courses in Gas Safe procedures, you don't really expect a detailed answer free of charge?

Or do you?

[Howsie]

Why don't you ask the manufacture the question? Only they know the answer as they designed the thing.

[Koogatubac]

Lol howsie, i like you 'DESIGNED THE THING' HAHA

[stratobuddy]

All 4 plumbers that gave me an estimate said the existing 15mm supply would not be big enough and they would have to run a 22mm pipe.

[croppie]

There are far too many reasons which we know and you won't. Satisfy yourself with this answer.

Because it does.

[mfgs]

All 4 plumbers that gave me an estimate said the existing 15mm supply would not be big enough and they would have to run a 22mm pipe.

What are the chances of all 4 qualified gas engineers being wrong?