Purging air from long propane line to pool heater


New member
Jun 2, 2021
Dorset, Vermont
I have an underground 1000 gallon propane tank. It’s at 85% full. One gas line feeds the house (H2O furnace, WH, oven/stove, a few gas fireplaces) and a separate line feeds my Pentair MasterTemp 400 pool water heater. However, right at the tank, there is a ‘Y’ fitting to each main feed, so all the propane used - for the house AND the pool - passes through one short length of what looks like a 1/4” or 3/8” copper line. Each line - after the “Y splitter” - has its own pressure regulator at the tank, and another just before entry to the residence house and to the pool house. I’m in-process of opening the pool, and I can’t get the pool heater to fire (it has no pilot, just a ‘glow’ igniter). The pool heater tries to go through it’s normal sequence of combustion chamber purge, gas valve open, and igniter glow. I can NOT see if the igniter is working. The heater will not ignite this year. It is a 2015 heater. There is a shut-off valve after the last pressure regulator at the pool house, and it looks like it has its own bleed port (the shut-off valve is inside the pool house, just prior to the connection to the pool heater). While trouble-shooting, I wish to rule-out low/no gas pressure, before I start buying new igniters and gas control valves and such. Any do-it-yourselfer advice on how to know that I am getting adequate propane and pressure to my pool heater? How does the little bleed port work on the shut-off valve? It is actually part of the body of the gas shut-off valve. It looks like maybe a 1/4” or 3/8” port, with a screw cap on it. I tried shutting-off all the propane consumption to the house, thinking that might be causing low pressure in the much longer gas line to the pool heater... but still, the pool heater would not ignite. Advice on bleeding the gas line from the propane tank? - Gary, in Vermont.


Well-known member
Mar 30, 2019
Las Vegas, NV
I am not sure that propane supply would be the first thing that I would check, especially since most people don't own a manometer to check the pressure. I would need to know the Make, Model & serial number of your heater. You would need to have at least a basic multimeter and be able to use it safely/competently in order to troubleshoot the heater at least minimally. Photos of heater overall with ther front cover off and photos of the wiring/components would be helpful in directing troubleshooting. Has the heater been cleaned and or serviced at all in the last 6 years?