Heater Gas line size

gatorson

Member
Sep 18, 2018
17
Fort Lauderdale
My previous plumber installed my sediment trap about 6 feet away from the inlet of the heater (directly out of the source line). He also installed a regulator/governor and reduced down to 1/2" pipe for a length of about 6ft to my 400k NG raypak heater (the distance from the meter to the dedicated regulator is about 75 ft and is 3/4" pipe). The heater then goes back up to 3/4" pipe into the gas valve. My question is it ok to have this short distance of 1/2" pipe and also have the sediment trap a short distance from the heater? Every video and manual shows the sediment trap directly outside the heater. The heater fires up properly, but am I starving it for gas? The plumber stated that he has high pressure and that's why he had to install a dedicated regulator right after the source coming from underground and that the 1/2" pipe is "fine".

Should I request to replace the 1/2" 6ft pipe section with 3/4" or is the way it is currently plumbed ok?

Thanks!
 
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PoolGate

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Jun 7, 2017
5,413
Damascus, MD
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I'd say your plumber probably knows what he's talking about. Fuel starved heaters are actually dangerous so I doubt he'd do something that caused this condition.
 

JamesW

TFP Expert
Mar 2, 2011
23,314
reduced down to 1/2" pipe for a length of about 6ft to my 400k NG raypak heater
1/2" pipe is too small.

Have the plumber do it correctly.

Below is the quote from the manual, which has to be followed.

*A 3/4" gas line can be used for up to 5' (1.5 m) maximum length from the gas valve in addition to the sediment trap
 

Futuresvt

Member
Mar 7, 2020
13
Georgia
What pressure is your gas line? 7 inch water column or 2 psi? If you have a regulator just before the heater than you might have a 2 psi setup. Do you have a regulator on each appliance in the home?
 

JamesW

TFP Expert
Mar 2, 2011
23,314
What pressure is your gas line? 7 inch water column or 2 psi? If you have a regulator just before the heater than you might have a 2 psi setup. Do you have a regulator on each appliance in the home?
They indicate that it is a two stage system with 3/4” pipe at 75 feet from the meter to the second stage regulator. Based upon an inlet gas pressure of 2 psig at a pressure drop of 1 psi, the first stage at 3/4” is good up to 150 feet. From the second stage regulator to the inlet of the heater gas valve can be 3/4” up to 5 feet assuming an inlet gas pressure of 10 in-wc at a pressure drop of 0.5 in-wc.

1/2” is unacceptable. Any warranty can be voided based on improper installation.

Note that the pipe length is “total equivalent length”, which is the length of all straight pipe plus a standard length equivalent for each fitting.
 
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