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Laars Lite 125k Natural Gas Burner Problems!

Laars Lite 125k Natural Gas Burner Problems!


Old 06-22-09, 07:16 PM
Thread Starter
Join Date: Jun 2009
Location: Macomb, Michigan
Posts: 3
Question Laars Lite 125k Natural Gas Burner Problems!

OK. I need some real help now. I have a Laars Lite 125k Natural Gas pool heater that will not remain lit.

The electric start works, the burners kick on and after 5 minutes or so the gas shuts off.

Two years ago I replaced the dual thermostat control panel and the ignitor control panel. Last year I replaced the pressure switch.

I am fairly good with electronics so I completly removed the dual thermostat, pressure switch, temperature sensors and jumped out the high temperature limit switches. THIS IS ONLY FOR TESTING! I understand the safety implications, I just wanted to isolate the problem.

So, all that is connected is the 240V to the ignitor control panel, gas valve and the little transformer.

Now the ignitor heats up, gas valve clicks and starts for a few seconds, and then shuts off. This cycles over and over.

Do I have a gas pressure problem, or is that small transformer that likely controls the ignitor likely going bad?

I really don't want to spend $100 just to get the pool guy here to tell me what I think I already know.....but I am not certain.

Any help would be very much appreciated!!!!!!!
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Old 06-23-09, 04:56 PM
todrut's Avatar
Join Date: Jun 2007
Location: USA
Posts: 1,212
could be flame proving rod, low gas pressure, or ignition control. You will have to eliminate one at a time
Old 06-27-09, 01:05 PM
Thread Starter
Join Date: Jun 2009
Location: Macomb, Michigan
Posts: 3
I replaced the tranformer, that didn't change anything but the heater stayed on for more than 5 minutes this time.
I changed the ignition control board a year ago, I hope that isn't it. Where is the flame proving rod? Is that what ignites the gas? There are two white wires from the 240V going to an ignitor, but I can't see anything else and there are no other wires connected to the ignition control. Just the gas valve and that kicks on. I will see what can be done about checking gas pressure, but nothing changed since I been here (unless there is spider webs in the valve...).
Old 06-27-09, 07:50 PM
Thread Starter
Join Date: Jun 2009
Location: Macomb, Michigan
Posts: 3
OK, I found a site that said that the Hot Surface Ignitor (This is the non-pilot version heater) serves two purposes, one to start the flame and the second to verify the flame is there by monitoring the heat.
To check if it is woring properly you need to verify the resistance is between 30 and 75 Ohms, mine is reading 95 Ohms, but still lights the burners.
I am curious hous the ignitor control module can tell that the fire is burning, since the only two leads going to it is the power lines. It must check the resistance through the circuit as it changes (resistance should change as temperatures change) but I am not sure. This is an $85 part, I will try to get one on Monday and check it out......

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