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Thread: basic question - natural gas heater use

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    basic question - natural gas heater use


    I just moved into a house with a pool set up by the prior owner. It has a natural gas Pentair heater. The heater has an exterior thermostat and power switch.

    The AC is also powered on off by a remote switch.

    The gas line has an on-off valve.

    Here's my question:

    How do I shut off the heater safely?

    I was told that the heater cannot be on when the pump is not running. Is this true? I also know people who leave their heaters on all the time.

    My concern is the gas - if the heater is shut off remotely, what would keep the gas from building up? It's probably a stupid question, but the natural gas makes me nervous, yet I can't imagine having to open and close the gas valve all the time.

    22k gal, 1 HP Hayward Super II pump, Hayward (not sure which model) DE filter, in ground plaster

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    Join Date
    May 2011
    Orange County, CA

    Re: basic question - natural gas heater use

    Most likely, the heater uses an electronic circuit to light the heater each time it is turned on by the switch on the front, or by the remote. If it does, then it also has an automatic gas valve that will turn on or off the flow of gas as needed. The heater also likely has a flow switch that will only activate the heater when the pump is running and there is sufficient flow of water in it. You could tell us the model name and number, and that would help. Also, using this model number, you should be able to download the operator manual from the Pentair site:

    If you are still concerned, you can use a wrench to turn off the flow of gas to the heater, and it won't present any danger. A 1/4 counterclockwise turn should shut it off, at least on typical gas valves.
    38K in ground pool with attached spa. Current equipment: Easytouch 8 (521150) with IC-60 SWCG with web control by Autelis, 1x Pentair IntelliFlo 011018 pump (for filter), 1x Pentair 2HP WhisperFlo pump (for waterfall), 2X Pentair IntelliBrite 5G 12V lights, Pentair MiniMax400 NG Heater, Pentair SMBW2060 DE filter. Zodiac Barracuda MX8 cleaner on dedicated cleaner line. Lighting/home automation controlled by Insteon/ISY-99i.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: basic question - natural gas heater use

    Welcome to TFP!

    Typically the heater power is either turned on/off by the same timer that turns the pool pump on/off, or is wired to the timer using a fireman switch (which insures the heater won't come on unless the pump is turned on). As long as the heater is powered down or disabled by the fireman switch, it will not come on and will not leak gas. As CraigMW pointed out, there is also a flow switch that serves as a backup to make sure it won't come on in case the pump is powered up but isn't actually pumping water. You can leave the gas valve open all season, though it is a good idea to turn the gas off for the winter.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: basic question - natural gas heater use

    There is also a hi limit temperature probe that will shut down the heater if the temperature exceeds a certain temp (150 in my case), which will happen pretty quick if the water isn't flowing. So even if the water pressure sensor fails, there's some additional insurance against total meltdown.

    A typical "firemen's switch" has another purpose - it will ensure that the pool pump runs for a certain amount of time after the heater is powered down. This makes sure that the water flow runs for a while to take he heat away from the heater, preventing damage to PVC pipes. My in-ground spa was not installed with this feature but it's survived for 15 years without any ill effect.

    So this takes us back to your first question. The "best" way to operate your heater is to only run it while the pump is running, AND to shut it off a few minutes before the pump powers down.
    18' X 33' X 54" AGP Morada 54" (16,325 gallons) (July 10, 2011)
    Hayward Power-Flo Matrix 1-1/2hp (SP1593)
    Hayward Pro Series Top-Mount Sand Filter (S-210T)

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