I have a propane (not LP) patio heater similar to this one...

8-foot patio heater

using a 20-lb. propane tank...

20-lb propane tank

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?


There seems to be a lot of confusion here. This unit is 8 feet tall, 40,000 BTU, only uses a 20-lb PROPANE tank, and this problem is occurring in ambient temps in the upper 50's and higher.

EDIT 2 - fixed (11/2019):

As per nameplate on the heater-

  • 40,000 BTU
  • 11" W.C.

Tried out this $10 regulator from Amazon, which is rated for 11" W.C. up to 80,000 BTU, just to see if it works, and it seems to have solved the issue. I know it's been a while since asking the question, but I put this thing to the side as a low priority since I had no solid method for troubleshooting other than guessing and part-swapping.

Flame stays blue the entire time, and on low setting, the tips are orange. The pilot flame is mostly orange now. See photos below. Not sure if that's normal, but the unit seems to be staying lit now and properly operational. I have not fully tested it on colder days so I will update this if needed. Tested in the 30's, and it still seems to work good.







  • Are you getting frost buildup at the tank valve? Rapidly expanding gas requires quite a bit of heat, which it takes from any nearby object or medium. Are you in a somewhat humid climate?
    – isherwood
    Commented Dec 18, 2015 at 17:57
  • @isherwood, there is no frost build-up at the tank. Temps in the high 50's a few days ago near Chicago.
    – Sparky
    Commented Dec 18, 2015 at 18:11
  • @isherwood, yes, I understand what you said about heat extraction. Of course outdoor temps are relevant as propane expansion within the tank is proportional to ambient temperature. Now what good is a patio heater in 58 degree weather if the tank gets too cold to function?
    – Sparky
    Commented Dec 18, 2015 at 18:17
  • Only possible: If LPG (not Propane) partial use and refilling will differentially tend to use Propane and not Butane so that over time the mix moves to mainly Butane. So at 1st you burn the Propanbe but as this runs down you get an almost pure Butane feed. Check this by trying a tank which has been refilled from empty. If it too does this the above is not the issue. If this IS the issue, emptying the tank (sob) and refilling cures it. Always emptying tank and not part refilling prevents the above. Commented Dec 19, 2015 at 0:27
  • @RussellMcMahon, it's definitely propane; refills purchased from national retailers. I have several 20 lb. tanks and this issue has been ongoing over many months.
    – Sparky
    Commented Dec 19, 2015 at 1:22

1 Answer 1


It sounds to me like a restriction at the regulator, not the control valve. You mentioned that the previous owner had done some work on it, make sure that he/she did not replace the regulator with one that does not deliver the design flow/pressure. In this case, adequate flow/pressure depends on proper regulator back pressure setting (they are rated in "inches of water" back pressure). If the regulator setting is too low, it will not deliver an adequate flow/pressure of gas.

If this is the case, the initial proper operation followed by diminishing performance is explained by the volume of gas in the 8' tall hose assembly, with a slow reduction in adequate volume being delivered by the undersized regulator. I had your exact problem when I attempted to swap out a leaky patio heater regulator with a BBQ regulator that had a different pressure setting.

Like this:

  • Regulator is initially open because of low (zero) downstream pressure.
  • 8' tall hose fills with gas until rated back pressure downstream of regulator is reached, regulator closes.
  • You open control valve and light heater, regulator opens as downstream pressure drops.
  • Damaged, defective, clogged, or undersized regulator cannot supply enough gas to maintain proper flame height as pressure drops, but does stay open and deliver gas according to it's pressure setting, which is not enough for adequate flame propagation.

It's worth checking, anyway.

  • 1
    I am now suspicious of the regulator. There is nothing on it indicating it's rating, however, there is a tag and it mentions "BBQ grill" in several places. Not sure if this is just a generic tag or if somebody actually replaced it with one from a BBQ grill.
    – Sparky
    Commented Dec 19, 2015 at 1:16
  • 2
    Purchased a new regular on Amazon that was only $10 so didn't mind trying it out. It was rated up to 80,000 BTU and 11" W.C. Seems to have fixed the issue and so far it's working.
    – Sparky
    Commented Nov 6, 2019 at 19:47

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