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Cant seem to get my Laars lite 2 to work. I changed the pilot, generator pile, on/off switch, thermostat, pressure switch, temp sensor board. I've jumped out high limits, fusible link, fireman switch. It will fire and stay lit as long as TH/TH is jumped out. As soon as I release the TH jump wire it shuts down. Please help with any suggestions. I have 530mv at valve from thermopile. It's a LG325N -THANKS
"generator pile"
Ah-h-h, yes. The much-hated (by pool service guys) millivolt heaters! You have perfectly described the miserably process involved in fixing those misbegotten pool heaters.
Putting a super-low voltage low-amperage millivolt controlled heater in a pool environment was a bad idea from the get-go. Millivolt systems barely run when they are new and corrosion free. Add a bit of corrosion at a terminal -- any terminal -- and they fail. And, when you put those heaters in a pool environment with all the moisture, chlorine fumes and acid fumes, corrosion is going to happen.
The only way I know to make those SOB's work is, after you've verified that gas valve works AND DOES NOT REQUIRE MORE CURRENT than the miserable thermopile can provide, you have to take a good digital voltmeter, and chase voltage drops around the wiring harness.
That said, I've have not worked on gas valves and heaters enough to remember that stuff well. I recall that there typically is a TH connection, and maybe a TR one, but I don't remember what they are -- I'd have to study the manual before I touched yours.
Frankly, I quit working on them.
Once they've corroded, even if you get them going again, they're never reliable unless you replace 100% of all the electrical connections, internal or external. A service guy who 'fixes' one of those beasts is too likely to get a "come fix it again; you charged me $200 and it only worked for a week!" for me.
So if you were my customer, I'd say, "Sorry, I don't work on those. They are too unreliable, and are likely to end with you hating me because you spent as much repairing the thing as a new one would cost or else me hating you, because you DIDN'T pay me. But, I'll be glad to install a new electronic heater. It will not only be more reliable, it will save money on gas."
But, if you've got the meter, the time, and the patience . . . they can be fixed. Just plan on 'fixing' it every spring.