I have a propane patio heater similar to this one...
I have an issue where the flame will slowly die down over a period of time. Let's say within 30 minutes it goes from full flame to something that barely stays lit. When the flame gets tiny, you can hear the propane hissing through the lines like it's being restricted.
If I wait an hour, I can re-light it and it's full strength again for a while and within 30 minutes, the problem will repeat.
I've disassembled and cleaned it out a couple times but this problem continues. The unit is never stored outside, however, I got it used and it's always had an issue staying lit. I have not yet replaced the thermocouple because the previous owner claimed this was already done.
I'm looking for troubleshooting suggestions that will conclusively narrow down the source of the problem and/or cleaning tips. The gas orifice at the pilot is too small for a pipe cleaner, but I've already tried solvents such as carb cleaner and it makes no difference.
The pilot is blue with an orange tip. When first lit, the burner flames are blue, but as it dies down, the tips turn orange.
What I don't understand is why it performs great when it's first lit. I'd think if this whole problem was caused by dirt, the flame would be restricted all the time.
Can anyone shed some light on this?
EDIT: There seems to be some confusion here. This unit is 8 feet tall, only runs on a 20-lb PROPANE tank, and this problem is occurring in 58 degree F and warmer weather.