Question about Hayward H Series Millivolt 250,000 Btu Pool Heater H2501

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Cannot tell where pilot, on or off is on gas valve

The plastic part that you push down was broken. I took it to a pool place to get a replacement and they could not get one. In the mean time they lost my broken one. I have a Hayward H250 series natural gas heater. My problem is that I can't tell where the pilot is compared to the on or off spots on the valve.

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I assume you have a W-R and should see a small notch down around 5 o'clock or so. That position is where you depress the knob to light the pilot.

Posted on Jul 04, 2009


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Jandy lg250n changed temp control still won't fire. any way to check millivolts

Yes, with a meter.
To check only the pilot generator, to see if producing enough Milivolts to operate heater, 'Clip' your meter leads to the ends of the pilot generator wires. Now push down on the gas valve knob in Pilot mode, and after a minute, the Milivolts can be read. Because the leads are NOT on the gas valve (most accurate way), you will need to hold down the knob, during the test.

To locate where an open circuit may be, why heater is not firing...
place one meter lead on one of the TH connections at the gas valve. The other lead will start at the next sensor in line away from the gas valve. Place on each side. If MV's present on 'in' side, and not on 'out' side that sensor is the reason. If no MV on 'in' side, but had it on 'out' side of previous sensor, then that wire is the reason for no fire.

Jun 08, 2015 | Jandy Pool & Spa

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The Hayward H Series Pool Heater with standing pilot uses a standing flame to safety initiate combustion, and the standing pilot flame is uses to generate about 0.400 to 0.450 volts DC to operate the gas valve.

CAUTION: Your Hayward H Series Pool Heater is essentially a furnace. Only qualified technicians with proper training and tools should repair your heater.

Once you have completed the pilot start procedure in your heater manual, the pilot flame should be visible but it is difficult to see. The pilot is located at the bottom of the heater, to the left side of the burner chamber, about half way between the front and back of the heater. Before attempting to verify the pilot, it's wise to turn the thermostat to the full counterclockwise OFF position. There are two useful methods to verify the pilot: 1) Before you initiate the pilot procedure, place a small mirror on the floor of the heater on the left side of the burner chamber, just inside the combustion area. CAUTION: DO NOT attempt to place or remove this mirror while the heater is in combustion mode! After placing the mirror, you should be able to see the pilot assembly. Follow your pilot start procedure, then you should be able to see the pilot flame in the mirror before you turn the gas valve knob into the ON mode. Be careful to remove the mirror before initiating combustion. 2) Only when the pilot flame is on will the thermocouple generate the circuit voltage required to operate the gas valve. During the pilot start procedure, while the gas valve knob is still in the "pilot" position and the pilot flame is on, the circuit voltage can be measured at the gas valve without danger of initiating combustion. Using a volt meter, measure the voltage between the RED and WHT wires on the gas valve terminals. This measurement should be between 0.400 and 0.450 volts DC. If below, the gas valve will not operate even if the pilot is ON.

After verifying the pilot, be sure to remove the mirror (if used) and the voltmeter (if used), turn the gas valve to "ON", and return the front heater cover before initiating combustion.

May 24, 2014 | Hayward 250kbtu Ng Pool Heater - Inground

1 Answer

Why won't the pilot light stay lit?

You have a "pilot generator" that sits in the flame of the pilot light. This generates a low voltage output from the flame of the pilot light. This voltage goes to the gas valve and tells the valve that the pilot is lit and to keep the pilot gas line open.
In almost all cases replacing the pilot generator will resolve the issue . They run about $60-$75.
Other causes may be the gas valve itself or a short in the safety loop, in either case should be looked at by a pool tech.

Jul 10, 2013 | Jandy Lite 2 Natural Gas Pilot Light...

1 Answer

I am a new homeowner. I have an H400IDLunit that is a pool/spa combo. The code reads "00" in the heater window and does not change when the unit controlls are pressed. I have an aqualink...

I don't know if there is a pilot light, spark ignitor or thermal ignitor. I would determine by inspection what kind it has. If you open the front cover you will find a gas valve. It can be identified by following the gas pipe that enters the side of the heater and attaches to the gas valve. If the valve has a control knob on it that has an off, on and pilot position then it is a pilot type. If this control is not on the valve then the unit includes an automatic ignitor.

To light a pilot equipped system place the knob in the pilot position, push it down, and use a flame to light the pilot. If you hear gas flowing from the pilot but it won't light then there is air in the line and it needs to be purged. Holding the pilot lighting valve down long enough will purge it but may take a long time. Periodically you can check it by trying to light it. If it lights watch it for a while before trying to turn the heater on to make sure it is fully purged. Once the pilot is stable and the thermocouple is heated the pilot valve can be released and it should stay lit. If not, try again.

Don't get down and look into the burners while you are trying to start the system because it could flame out and burn your face. If you turn on the heater again then the gas valve should come on and the burner should light. You can usually hear a loud snap when the gas valve come on. You should then hear the gas flow to the burner. If the burner doesn't light you should be able to smell the gas. If it lights exhaust will be coming out of the vents in the top of the heater.

I am sure you will have more questions so please respond with them. I hope this helps.

Sep 04, 2011 | Hayward H-series Electronic Gas Pool...

1 Answer

Can't light my Raypak Pool Heater.

Often you can see the pilot if you use a small mirror. With the button on the gas valve pushed down you should get pilot. Once the pilot is lit it warms the TC(thermocouple) creating the static charge to open the gas valve on it's own. The TC is set in the pilot assembly. It will be a small tube like piece with the wires coming from it. Some times you can pull and replace it but I will usually get the whole pilot assembly and just replace that. It will probally be rusted and can be cloging the tiny orface on the pilot itself.
If you have a milivolt meter you can check the TC by pulling the wires that come from it at the gas valve and with the button on the gas valve pushed in and a good flame you should get 500-700 MV from the TC. This is 1/2 a volt+ so you will need a MV meter. But this will tell if your TC is bad or if your valve is bad.
Good luck.

May 12, 2010 | Raypak Free Hydraulic Lift Gate Delivery -...

1 Answer

Raypak boiler nat gas for domestic hot water model W2-0514BEARDAA or 334-056197 having problem with no gas to gas valve, trying to diagnose gas selenoid valve that is pre-gas valve. Pilot lights but...

Guessing you have a milivolt heater. While your pilot will light when you push the pilot light button down you need to generate 200mv to open the selenoid for the pilot and another 300mv for the main valve. This can be checked by removeing the leads from the pilot generator (wires from the pilot), Push the pilot button down and hold in place (a small screwdriver wedged in becide the button will do this) Then check the milivolt reading from the generator. This reading should be between 500 and 700mv (1/2 to 3/4 of a volt) If you don't have this your pilot generator is bad.
If you do then you need to hook the leads back up to the valve and unhook the saftey circut leads and try to light the pilot again. If the pilot still won't light your gas valve is bad. If it does then you have a problem in your saftey circut and you will need to check each item in the circut by removing and jumping past.
This would be more in line with just the main side of the valve not opening. So I'm sure you will find it to be the pilot generator or the valve being bad. As I stated before this system only runs on 1/2 a volt so all connections need to be clean and tight also. Could be other problems but this should cover the common reasons. Good luck.

Mar 12, 2010 | Raypak Free Hydraulic Lift Gate Delivery -...

1 Answer

Can light it but it won't stay lit

The thermocouple is not producing enough voltage to keep the valve open. Try holding down for a longer period of time to allow the thermocouple to heat up, or you could have a loose connection on the gas valve. Loosen then Tighten all connections on the gas valve and try it again, if that doesnt work replace your thermocouple.

Jul 10, 2009 | Hayward H Series Pool & Spa Heater 200k...

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