May be the regulator valve
 I had this problem and got gas to stove, hot water heater, and furnace. The furnace would not ignite. Mobile tech came out and put a gas meter on the stove and determined the regulator had a momentary drop in gas pressure when the furnace valve opened which would not allow the furnace to ignite. Changed out the changeover regulator, and problem fixed!  Good luck!
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2010 Mountaineer 285 RLD, 330 watts solar, 600 watts sine inverter, 3 type 31 agm batteries, Traveler antenna
2010 Dodge Ram 3500 SRW, 18k Reese slider, Honda 2000i, Firestone airbags
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