Propane Heater Troubleshooting

[PAToyota]

I've been trying to track down an answer to an issue with my propane heater - one of those dual element versions that mounts to the top of a propane tank like the Mr. Heater Original Series ones (although this one isn't a Mr. Heater).

With colder weather, I'm using my propane heater again. Everything works fine if I just use the one element, but after five to ten minutes using both elements the one element starts "roaring" and the flame has jumped off the element and the element slowly goes cold - isn't glowing orange as normal - but it apparently has enough heat to keep the thermocouple open as it continues to burn like this until I shut it off. If I just use the one side, that one will burn forever without any problems - it is always the same side that has the problems even if I only use that one side. Tank is full, so I don't think it is an issue with getting low and not having enough pressure.

Looking over things, nothing looks different from the other side. Any ideas on what needs to be replaced/fixed?

[uglyscout]

WAG:
Is the valve freezing? if it is icing up inside/outisde/wherever it could be restricting flow enough to not allow both burners to run properly..

[PAToyota]

No signs of freezing. I had similar thoughts that somehow it was constricted to limit >both< burners at the same time but that side won't run even on its own - same problem - so it isn't like running both burners is pulling too much capacity.

[mike holt]

get a manometer which measures pressure in inches of water column. test at the heater while it is running. sounds like a regulator or too small of a gas line for the load. propane pressure should be 10-14 inches of water column. That's equivalent to about 1/2 of 1 psi. how many btu's is this heater at maximum capacity? I can help with the regulators and what size lines you should have. or at least eliminate them from the equation.

oops. just saw you said that one burner wouldnt run on its own. kinda rules out my theory.

[Wyoming9]

Almost sounds like the one that doesn`t work is getting to much air. A leak in the line will draw in air. I had a problem like that with a single unit.

A real bugger to figure out.

[urbanmuddboger]

no no just look at the mixer
there is a hole in the tube that holds the heater up and inside that hole is the mixer the little brass jet just blow that out prob just a cob wed covering the mixer when i was a mill wright i used to fix them every year (well not all of them some were "unfixable" and ended up at my hose:D) and this was the prob 98% of the time