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John Rumm John Rumm is offline
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Default How do I calculate gas pipe size?

Toby wrote:

In the process of installing a new boiler, but am not really sure how I
should calculate the gas pipe size to the boiler.


You need two things - the maximum gas flow rate (in m^3/hour) the boiler
will draw (this will depends on its max power input). and the tables
from this document:

http://www.cda.org.uk/megab2/build/p...tallations.pdf

The gas meter is just under 5 meters away (as the pipes will run) and
this will be the only gas appliance in the house (the Kitchen is the
opposite direction to the boiler too, so if any gas is needed or there,
it won't need to branch off of the run the the boiler)

Can someone possibly help me understand how to calculate this!?


Basically assume the boiler needs at least 20mBar dynamic pressure at
its input. The governor at the meter will be set to supply at 21mBar,
therefore your pipe needs to drop no more than 1mBar dynamic pressure.

(There will need to be two bends in the pipe, I assume swept bends are
going to be preferable here?)


From memory, an elbow counts as an equivalent length of 0.5m of pipe,
and a bend as 0.3m equivalent. So if you have five meters of pipe with
two bends, then that is an effective length of 5.6m.



--
Cheers,

John.

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