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Laars Mini-Therm JVS160 short cycle
I have a residential Laars Mini-therm model JVS160NDIS Serial # D02JE0076.
I had it installed new 6 years ago. The unit has worked flawlessly until late last winter when it will ignite, run for 15-20 seconds, shut down, ignite again, run for 15-20 seconds........ Sometimes it will ignite and rum for a complete cycle until thermostat shuts it down. Thermostat has been replaced—no change. Flue, pump, water supply are all fine. Unit is super clean and well ventilated. House heats fine, gas usage is the same. Thanks for your help.