Question about Hayward 100,000 BTU Pool Heater H100ID1 - Above Ground

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I have a Hayward above ground pool heater. It ran fine last year and the first month of this year. It starts fine and runs for about 20-30 min and then shuts off. The vent is still running but not the heater. The filter and the pool water are very clean. I have replaced the water pressure switch but still the same. The filter is pusing water to the heater at about 18 psi. It sounds like a previous question where the gas orifice was blocked but mine runs longer before it decides to quite heating.

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  • PHILLIP COOPER Aug 23, 2010

    Thanks for responding. Are you talking about the Hi Temp Sensors which are in-line next to the Water Pressure Switch? And, do you know where I can get these for less than $100. Do I need to replace both sensors?

  • PHILLIP COOPER Aug 26, 2010

    I thought the bridging thing solved the problem because right after I did it the heater ran for a good 4 hours. But the next day it was up to it's old tricks. Is it possible that dripping connections at both the inlet and outlet could be an issue? As I recall, the heater didn't start acting up till the leaks started. Is there something that senses that? I have already replaced the water pressure switch. Any other thoughts?

  • PHILLIP COOPER Aug 26, 2010

    Any thoughts on my reply to you last night?




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It would seem that the thermal protection is kicking in because eiter the unit is overheating or one or both of the sensors are faulty.
You obviously know where the water pressure switch is, so follow the red wire from the switch to the heat exchanger. There are 2 identical "nuts"(temperature sensors) with a yellow wire connecting them. Once the unit has shut down open the it. Remove the red wire from the water pressure switch and also the red from the air pressure switch. Measure the resistance between these 2 wires. They should measure close to 0 ohm. If not then one of them is open circuit and may need replacement but you will need to test each individually to determine which one.
This in no way proves a faulty temperature sensor. It just means the unit is shutting down due to overheating.
Make sure there are no obstructions to the air flow in or around the unit as this could also cause overheating. Since this unit was working before and is not a new installation I'd recommend replacement of the temperature sensors.

Posted on Aug 20, 2010

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  • Rene Rossouw
    Rene Rossouw Aug 23, 2010

    The high limit switch can be replaced individually. You will need to test it with the multimeter or bridge it(connect it's leads together) to confirm. The kit(part no IDXHLK1930) should be around $70 - $80.
    The 135 degree high limit switch(part no HAXHLI1930, Heaters built after Oct 2000) is universal to several Hayward units and can be obtained seperately for around $30.

    Here is one site that sells online:
    but if you search for the part numbers you will note a wide variety of suppliers and an equally varied price range.

    Note, but not recommended. The limit switches are there to prevent
    A/ the water heating to such an extent that it becomes dangerous to humans and
    B/ the water heating so much that it damages the plastic components of the unit
    however they can be bridged.

  • PHILLIP COOPER Aug 24, 2010

    I connected the leads together ( I can't tell you how without the Electrical Police coming to my house) last night and the heater ran for about 4 hours (PTL). Now the question is do I buy 1 135 degree high limit switch(part no HAXHLI1930 or should I buy 2 of them? Is it safe to assume that only 1 of them is defective? I found them on for $23 each.

  • Rene Rossouw
    Rene Rossouw Aug 24, 2010

    I'd suggest doing the same again with the switches but only one at a time.
    Below is a simplified wiring diagram for all the safety controls. You'll see the limit switches in series. Bridging one at a time will show up the faulty switch. Bridging v and it keeps running then vi is your culprit.

    i - Power
    ii - Panel locked switch
    iii - Thermostat
    iv - Water pressure switch
    v - Temp limit
    vi - Temp limit
    vii - Air pressure switch
    viii - Ignition module
    ix - Gas valve
    x - Induction blower and temperature switch

  • Rene Rossouw
    Rene Rossouw Aug 27, 2010

    A dripping water leak will not be detected by the water pressure switch(It's not that sensitive) but I think we're a step closer to solving this one. Have a look at the underside of the ignition control unit.
    Here are some pics I found on the net :
    Underside :
    Component side :
    They are prone to failure due to the solder points cracking at the connector causing an intermttant connection. Remove the module completely and resolder all the visible points on the board focusing especially on the connector. This may save you the cost of a replacement unit. You'll need an electric soldering iron and some solder. When soldering let the iron heat up, take the solder and touch the tip of the iron, this will melt some of the solder onto the iron. Now place the tip of the solder wire on the point you want to solder and touch the iron to the soldering point momentarily. This will let the solder already on the board melt and also the solder wire. Dont push down on the solder wire or you'll get too much of it onto the board. You'll get the hang of it pretty quick. If you do have too much solder on a specific point a solder ****** works well. If you dont have one handy use a paint brush to wipe away the solder and try again. A quick blow of breath will also do the trick. You'll now have little streaks of solder all over the board but these can be removed using the iron.
    Having water leaks inside the unit can lead to short circuit and possible electrocution at worst, and the earth leakage to trip at best. Get them repaired.



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