Propane back up-not

[Woodfarmer1]

I have a munchkin condensing boiler that won't fire, the code says the pressure is low. The wood boiler runs the P/S at 20 psi, and when it's hot the propane runs up to 15psi, but as the wood burns out and the P/S cools to less than 100* (which is where the propane boiler aqua stat is set) it won't fire and the pressure at the prop boiler drops to zero?

I can't find any leaks in the system and even closed the air bleeder valve with no luck

 

[Fred61]

I wonder if your expansion tank is flooded or if it is adequately sized.

 

[timberr]

I agree with Fred, I would check the expansion tank. I also run a Munchkin for backup. I only run into the low pressure situation in the spring when I shut down my Eko 25.

Good luck

 

[Woodfarmer1]

i put a gallon of water into the system and this brought the pressure up to 24psi and the boiler fired

 

[timberr]

Good news, my Munchkin fires with 10 PSI on the gauge, I thought I read that the pressure switch was looking for 12 PSI.