Gas Pipe Calculation

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Hello,

Jus a quick question for any gas engineers. Have been working this out in my head but really need a second opinion.

Basically I have looked at a job to replace an old Ideal 2CF100 boiler with a Conventional Greenstar boiler.

Job is very straight forward but boiler is a fair distance from the meter so I need to run some 28mm.

It is about 25 mtrs and the only appliance is the boiler. At the moment it is all piped up in 22mm from the meter to the boiler.

I can get access to everything and run 28mm as far as needed but my question is regarding the first meter or so of pipe.

It is in an old victorian style house in Edinburgh with rally fancy floor tiles and the only way I can get to the pipe is to rip them up.

Can I run the first meter and a half in 22 then go upto 28 right to the boiler?

Looking at the chart 2 mtrs of 22 can allow plenty of gas through but this is a scinario I have never had before as usually I would take 28 straight from the meter.

In theory the correct amount of gas could get through a 2 mtr length but it just doesn't seem right.

Would appreciate any advice.

Thank you.
 
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If the theory says 22mm is ok, then 22mm IS okay. Why charge a client more cash, or waste your own just because you gut disputes the chart?

If th eold boiler is a si,milar input, and still working, why not jack it up to maximum gas rate, and measure it, just to reassure yourself?
 
To answer the actual question, you CAN run 22mm and then 28mm. I'm not sure how would calculate this, but you obvously don't trust the calcs anyway.
 
Hello,

Thanks for the reply.

Sorry I should have been clearer.

The existing pipe comes out in 22 but at some point changes to 15mm. The pipes have been boxed inide a false sealing with no access and end up under tiled floors, again with no access.

From my calculations regarding the new route I can get away with about 11 meters of 22mm from the boiler then will need to take 28 back to the meter.

I can get to within about a meter and a half of the gas meter so it would mean 22 from the meter , then 28 for a fair bit then back to 22.

I know I cant get emough gas through if the full distance is in 22 but by having say 2 mtrs of 22mm pipe then I would have thought there would be enough gas available.

Sorry if it does not make sence.
 
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If your are allowed 11mtrs of 22mm pipe it doesnt matter where that pipe is so a short length of 22mm at the meter will be fine
 
This question, as well as the answers, belong in the CC and nowhere else.
 
Yea well if anyone actually got back to some of us regarding the big CC, that might actually help a lot.........been waiting since before xmas.......
 

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