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Thread: Hayward H250 troubles

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    Hayward H250 troubles

    Hello all,

    I having some trouble with my Hayward H250 millivolt heater. It worked the first day the pool was opened, about 3 weeks ago, but I haven't turned it on since I tried again yesterday. The pilot is on but the main burner won't come on. I turn the switch to "on" and turn up the thermostat but nothing happens. I don't hear anything. I have a manual and it says I can jumper the "TH" terminals on the gas valve and then work my way through the pressure switch, thermostat, etc. Is this the first steps I should take then? Are there any other things I can check first? There is some corrosion on the terminals at the gas valve. I'll try to clean those up.

    Thanks!

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    TFP Guide

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    Re: Hayward H250 troubles

    I am not real familliar with that particular heater but, the principles are ther same on all of these units. with that said, there should be 3 terminals on the gas valve. Generaly they are marked TH, TH/TR, and TR. The TH/TR is not connected to anything in the gas valve, it is just a connection point for one side of the power source (Power Pile in this case) and the themostat. The TR terminal is one side of the connection for the valve from the power supply and the TH is the other side of the power connection to the valve thru the thermostat. If you use a jumper wire to jump the TH to the TR the valve should open and light the burners. This will effectivly bypass all sensors and the thermostat as wellDon't wory about getting shocked as the voltage is less than a flashlight battery. If it does not light then you need to check the output of the power pile (sometimes called a thermocouple). you will need a digital multimeter to see if it is putting out 750 Mv (milivolts) if it is not puting that out then it (power pile)will need to be replaced. also visualy check it to see if it is clean. sometimes soot buildup can cause them to put out a weak voltage. If it does light then the problem is most likely somewhere up stream in the wiring of the various sensors. finding the bad one will take some work as some of them may be hard to get to or find. The theory on how they all work is simple though. Each one is essentialy a switch that is either off or on. When all of them are on the voltage flows thru the wiring to the gas valve and allows the burner to light. If any of them is off then the circuit is broken and the gas valve will not work. To chesk these you will need to remove both wires from each sensor and jumper across the wires to complete the circuit. If nothing happens, then hook those wires back up and move on to the next one and do the same. Again this is all very low voltage so there is no shock risk. Think of this as trying to find the bad bulb in a string of christmas lights where they all go out when one is bad. to test if it is a bad thermostat jump across the TH/TR and the TH terminal on the gas valve with the wires hooked up.

    good luck and let us know what you find. Dan
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: Hayward H250 troubles

    Check all of your safety switches first before messing with the gas valve. It could be just the pressure switch or one of the other safeties. Start their first as they all must be working before the gas valve will get signaled to open.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Re: Hayward H250 troubles

    It turns out it's a faulty on/off switch, so a relatively simple fix. I bypass the switch and it fires up every time. Thanks for the help. I haven't been able to find an online distributor in Canada for the part, so I'll check with my local pool store.

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    Re: Hayward H250 troubles

    Quote Originally Posted by poollover2012
    It turns out it's a faulty on/off switch, so a relatively simple fix. I bypass the switch and it fires up every time. Thanks for the help. I haven't been able to find an online distributor in Canada for the part, so I'll check with my local pool store.
    Check with any electronics stores that you might have. Here in the U.S. we have Radio Shack and they carry simple switches such as you're looking for.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Re: Hayward H250 troubles

    Quote Originally Posted by ps0303
    Quote Originally Posted by poollover2012
    It turns out it's a faulty on/off switch, so a relatively simple fix. I bypass the switch and it fires up every time. Thanks for the help. I haven't been able to find an online distributor in Canada for the part, so I'll check with my local pool store.
    Check with any electronics stores that you might have. Here in the U.S. we have Radio Shack and they carry simple switches such as you're looking for.
    Thanks. Finding alternate switches shouldn't be a problem, just not sure if they would be the same size, as to fit in the existing slot.

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    Re: Hayward H250 troubles

    Resistance would be the main concern for the switch on a millivolt heater. (just FYI)
    Mark McCrary

    25k Gallon pool/spa Hayward equipment, 3hp pump, DE6020, Goldline control panel, In house control and Poolside remote.

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    Re: Hayward H250 troubles

    You can always jump out the ON/OFF switch with an alligator clip just to get it running, while you're waiting on the replacement part. You're not bypassing any safeties that way.

    I have a YT channel on tips/tricks to diagnosing/fixing this heater: https://www.youtube.com/channel/UC0P...wd0OC4RUZfVflA

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