Jandy Laars LX Pool Heater / 400,000 BTU / Natural Gas Logo
Posted on May 26, 2009
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5 year old Laars 25,000 LX won't ignite.

As a test, I have installed this used pool heater on our pool with a 1.5 hp pool pump. I get no LED problem read out, but the gas won't ignite. The blower comes on for about 30 seconds, then goes off completely, at which time the screen says "Low Pressure". This heater sat unused for about 3 years, and had only a summer's jacuzzi use prior to that. Good shape.
Is there a pressure problem? What is the problem?

I am intending to use this as an external heater to heat a small jacuzzi with a 1 hp motor. Will the jacuzzi pump provide enough pressure to fire the heater?

Thank you!

  • tbutz111 May 27, 2009

    The gas line is new and gas is available. How can I know if the heater gas valve is malfunctioning? Thanks!

  • tbutz111 May 27, 2009

    The LX model has an electronic igniter, not a pilot. I'm not sure I can hear if there is gas over the sound of the pump and the blower. There is a glass circular window the size of a quarter on the front wall of the heat exchanger. I'm guessing I can see flame through this. Can I also see the igniter and spark through this window? Thanks for all the helpful comments!!

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  • Posted on May 26, 2009
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The low pressure indicator is for the gas pressure not the water pressure. The heater won't ignite because it's not getting gas to the igniter. Check gas supply, if okay, check gas connections, valves, etc.

The 1 HP motor should be fine on the jacuzzi.

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  • Anonymous May 27, 2009

    Accurate testing would require some equipment and expertise which is best provided by a pro.



    Although the screen is reading low pressure, this may be an erroneous error msg, and the igniter may not have a hot enough spark.



    About the only thing I could reasonably suggest is to listen when the gas is turned on to see if you hear any gas moving, and watch the igniter to see if it sparks.



    If you can't do this without taking the unit apart, I would not suggest doing it -- this can be very dangerous, and needs a pro to do it safely.

  • Anonymous May 27, 2009

    It occurred to me that instead of an (spark) igniter, you may have a pilot light -- do you know?

  • Anonymous May 27, 2009

    Yes, I would say you should be able to see the spark through that window.

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  • Posted on Aug 19, 2009
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SOME OF THESE DO NOT USE SPARK THEY HAVE GLOW RODS REMOVE DOOR AND LOOK AT THE BOTTOM OF THE HEATER AND SEE IF THERE IS A GLOWING RED LIGHT ( IS THIS A TRUE LX OR LXI )

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  • Posted on Jun 23, 2009
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The ignitor is a hot surface type it does not spark. If you look in the "window" during start up you will see a glow best done when it is dark.
The problem sounds like the air flow switch You said the fan comes on for 30 seconds and stops. You are not going any further into the start cycle becaues it is not sensing fan air flow and shutting down.
Look for the air tube clear or white about 1/2 wide make sure it is connected and does not have any holes in it. Mice/rats chew trough it all the time. Don't blow in the tube this will damage the air switch

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