I'm looking to have few gas appliances including a natural gas dryer
installed in a house which uses natural gas for heating and hot water. I've
been reading information on the net trying to make sure that what the
contractors are proposing will work, and right now, I can't see how.
It seems the rules are "measure the longest run in the house, and use a
given column in a table to find out what each diameter pipe can carry," and
"once you restrict a passage with a smaller diameter pipe, that limits how
much gas will ever pass beyond it no matter how large pipes beyond the
narrowest segment are."
I know for the measurements, I'm starting at the meter, but it's unclear
what the "end point" is. The point where the gas dryer would attach would
be just about 60' from the meter, but there will be a flex hose of a few
feet between that point and the dryer itself. Do I have to use the 70'
column because of this flex hose, or do I use the 60' column?
Once I go to the 60' column, I see that the 1" pipe off the meter will carry
enough gas for everything I need (259 cu ft/hr.) So far, so good. The
problem is, the furnace needs 90 cu ft/hr, and the internal regulator takes
a 1/2" pipe. About two feet of 1/2" pipe are run from that internal
regulator to the outside of the furnace, which attach to an elbow, which
attach to a 3/4" to 1/2" adapter. Now the 3/4" pipe can carry 127 cu ft/hr
to a point near the furnace, which is enough, it would appear the 1/2" pipe
going into the furnace (because the longest run in the house is 60') can
only carry 66 cu ft/hr. How can this work?