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.

 

[Dotty]

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?

 

[stevetheplumber]

well they could have met in the pub before they went to stratos and decided to have him over for a few quid

 

[Koogatubac]

well they could have met in the pub before they went to stratos and decided to have him over for a few quid

Hahaaa

 

[Nostrum]

If the boiler is suitable for LPG changeover then 9 times out of 10 it will have a 15mm inlet so you could be moaning that you need to use a reducer for your 15mm LPG supply because they put a 22mm inlet on it! like I used to on Worcester Juniors, especially when it says in the book the minimum size must be 22mm with no exception for LPG. That was until I phoned them and kicked up stink for them to confirm it was actually ok! The annoying thing was that Worcester are one of the minority who still sell an LPG version where as most just give you the option to adjust.

 

[REDSAW]

If the boiler is suitable for LPG changeover then 9 times out of 10 it will have a 15mm inlet so you could be moaning that you need to use a reducer for your 15mm LPG supply because they put a 22mm inlet on it! like I used to on Worcester Juniors, especially when it says in the book the minimum size must be 22mm with no exception for LPG. That was until I phoned them and kicked up stink for them to confirm it was actually ok! The annoying thing was that Worcester are one of the minority who still sell an LPG version where as most just give you the option to adjust.

good answer

 

[Mike Jackson]

If the boiler is suitable for LPG changeover then 9 times out of 10 it will have a 15mm inlet so you could be moaning that you need to use a reducer for your 15mm LPG supply because they put a 22mm inlet on it! like I used to on Worcester Juniors, especially when it says in the book the minimum size must be 22mm with no exception for LPG. That was until I phoned them and kicked up stink for them to confirm it was actually ok! The annoying thing was that Worcester are one of the minority who still sell an LPG version where as most just give you the option to adjust.

Have you ever tried converting a Worcester from NG to LPG? Before they started selling the dedicated LPG versions you bought a kit with a new code plug and a little sticker. Getting the thing set up with the correct readings was an absolute mare. It also bugs me that you buy a boiler for LPG and it comes with a brass olive in the gas connection.

 

[Nostrum]

No the firm i used to work for were fitting vaillants which had a changeover kit you had to buy that consisted of a sticker and an A4 piece of paper!

We only changed over to Worcesters because of the accreditation business and the 5 year warranty and they were always the yellow stickered ones pre adjusted.

Nothing surprises me with Worcester, they've gone right done the pan and IMO the CDI was the last decent range they made. Wouldn't class them any better than Chaffeteaux or Ariston now with the all plastic internals and the way in which they are sold (mass to contractors and builders, B and Q etc) will see their reputation go down the pan in the next few years as they start dropping like fly's because of how they were fitted.

 

[Dotty]

What really worries me is that they've taken over Buderus and have included a rebadged GB162 in their range. I like the 162, It's a well made bit of kit that rarely gives any problems. How long before wb start pushing them into cutting corners to increase the bottom line?

 

[stratobuddy]

The only point I was making was that if boilers needed at least a 22mm supply, why did they have a 15mm connector!

 

[Mike Jackson]

They don't if a boiler has a 15mm connection all they need is a minimum of a 15mm connection. It's then up to the gas engineer to work out the pressure losses on the pipe run and size the rest of the pipe work accordingly. There's a lot more to gas work than just joining pipes together.

 

[stratobuddy]

The only point I was making was that if boilers needed at least a 22mm supply, why did they have a 15mm connector!