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I bought one of those 8 foot patio heaters that use a 20 gallon propane tank to replace my old one.

It will run fine for a couple of hours on a full tank and then behave like it is running out of gas. Until eventually not being able to heat at all. If I leave it off for an hour and start it back up then it runs better and can heat. If I leave it until the next night then it runs 100% until degrading slowly again.

This sounds like it is directly related to the components heating up.

My old one that I used for many years never exhibited this problem so I think I can rule out my tanks and environment.

My guess is that some metal parts in the new heater are not made of the same metal parts as in the old heater. That the metal is inferior for the task and is expanding more under heat and restricting gas flow. But that is just my wild uninformed guess.

It was suggested that I return it but how am I going to prove it's not behaving properly and if its a problem with the design getting a replacement won't help.

I am thinking of changing the regulator with the one from my old unit next.

  • I have an older propane cook stove in one of my off-grid cabins, but it also has the capability to use natural gas if needed. However, there are two vents that need to be closed in propane use, but slightly open when using natural gas. Perhaps your device is similar, and you've got it in natural gas mode? Note that I've never used it in natural gas mode before so I am unsure if that would cause the symptoms you're experiencing. – stevieb Nov 14 '18 at 23:43
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    It may be freezing at the valve I have a 400k btu propane heater that runs on 100lb tank it draws so much propane through the line that it ices up until the flow is restricted to nothing. – Kris Nov 15 '18 at 0:22
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    powerblanket.com/blog/…. – Kris Nov 15 '18 at 0:25
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    Rather than icing, the liquid propane may be cooling so much as it boils into gas that it won't boil anymore, leaving you with no gas left. I'll guess that the colder the weather, the quicker this happens; does it? – Daniel Griscom Nov 15 '18 at 1:12
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    @Kris Propane won't actually become solid at any pressure until it's close to -200°C. But, as it cools to and past 0°C, its vapor pressure gets lower and lower, until there's not enough to push the gas out of the tank. No freezing involved. – Daniel Griscom Nov 15 '18 at 12:58

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