Propane weirdness

[Vagabound]

I'm not quite sure where propane questions fit in this forum, so I stuck it here.

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I am new to using propane for any purpose, so I'm still learning.

I'm using a new 20-pound propane tank connected to a typical two-burner Coleman stove for cooking. For the most part, everything is working fine, except the very common problem of the flame height not staying where you leave the knob position. That's being talked about in another thread.

Something weird happened just the other day and I'm not experienced enough with propane usage to know what it might be. 

Long story short, after lighting the stove, it usually burns pretty high. I was heating water for a shower as I regularly do now. As I was puttering around doing other stuff waiting for the water to get hot, I could hear that the flame had gotten lower. I checked and it had gotten lower. In fact, the flame was kind of weak. I turned everything off including the tank valve, and then turned it back on, and everything was normal. Problem gone.

A couple of days later, something very similar happened, except that this time, the stove turned itself down, and then after about 2 minutes, it resolved on its own and the flame went back up.

Possibilities:

1. Poltergeist - Could be, but I doubt it. I have a full can of Ghostbuster spray.

2. Tank malfunction - Seems highly unlikely as the tank is almost brand-new, has been working fine for about two months, and tank malfunctions wouldn't likely repair themselves.

3. Gas pressure problem - I don't see how it could be this because there's a pressure gauge on the tank and it shows everything is fine and the tank still feels mostly full.

4. Filter - When I bought a filter for my Buddy Heater, I bought a spare. And then I decided to put the spare in line to the Coleman stove. It is screwed directly into the Coleman stove regulator. That has always worked well enough, but now I'm suspecting this is the cause of the problem. How exactly? I don't know. 

The filter could be getting clogged, but that seems unlikely. Reason is that the stove uses far less gas than the Buddy Heater, and the filter on the Buddy Heater is still fine. 

I'd appreciate any reasonable ideas about what could be causing this.

Tom

 

[Almost There]

I'd take the filter out of there for starters - the only reason to put a filter in line is for use with a catalytic heater like the Mr. Buddy.

As to the propane weirdness - it very well could be the filter getting partially clogged or more likely it's the hose itself. The reason you need a filter with the Mr. Buddy is because standard propane hoses are constructed with a plastic liner inside that tends to break down and clog things up.

I had a hose that wasn't all that old start to break down inside - stove wouldn't light at all. I tried every combination of tank, hoses (I had 2 at the time) and appliances to figure out which part was the culprit. The hose seemed to be the key so I took it to the propane place in Quartzsite. They hooked it up to one of their tanks and sure enough, no one could get gas out of it.

 

[Spirituallifetime]

I've had similar problems with my colman stove. Check the tip that goes into the hose at the stove conection, it can get cloged. There is a screen in the tip, clean it and the stove should work fine. I seem to have this,problem every time I reconect the tank.after refilling it.

 

[hepcat]

Propane pressure is also very sensitive to variance in temperature, and the reason that propane systems have pressure regulators. A warm gas, pushed through a small aperture, cools and the pressure drops. That's the very premise behind an ammonia absorption refrigerator, and I suspect is often the reason that propane stoves start out burning high and then self-regulate to a lower flame height. That's probably also why you tend to see inconsistent performance from day to day and place to place. I suspect that altitude and barometric pressure also have parts to play also in the performance of a propane stove in camping.

Or... it could just be that your hose's screen filter is getting clogged.

 

[John61CT]

Make sure your hose is the teflon? lined type, plain rubber needs replacing more frequently, breaks down to an oil that clogs jets (why Buddy filter).

And you do know all rubber hoses should be replaced pretty regularly? Permanent installs replace with copper.

 

[jimindenver]

A possibility is as the propane boils off creating gas it has a cooling effect. The lower temperature means the propane boils off slower creating lower pressure in the system. This can be more noticeable in cooler temperatures to the point that you may be able to light a device in freezing weather only to have it become unusable after a while. I have had this happen with a small propane heater on a 1 pound bottle. I would have to shake the bottle every so often to get the heater to relight.

 

[Vagabound]

Thanks to all for the info so far. A little more information to answer some of your questions or comment on your suggestions.

Hose Type:
I have two 20-pound tanks in two black hoses. Both hoses are Mr. Heater hoses. I use one for the Buddy Heater and the other one for the Coleman stove. Both hoses are about two months old.

Filter:
I could remove the filter that's in the line before the stove, but I can't see any reason that that filter would be an obstacle if the other one is not. Hmm.

Clogged Tip:
Wasn't aware of that. Haven't checked it. Will do. Thanks.

Temperature:
I was wondering if ambient temperature would cause any changes in gas pressure. All I can say is what I've noticed. For most of the time that I've owned these tanks and use them, it has been cold. This problem showed up after it got surprisingly warm in the last couple weeks. However, I'm doubting that's the cause. Reason is that I was in Yuma a few weeks ago and it was up into the eighties for at least a week without any propane problems.

Teflon Hose:
No idea. I have whatever Mr. Heater makes and sells for its buddy heaters. Regarding regular replacement of hoses, what's the definition of regularly?

Tom

 

[John61CT]

Mr Heater sells both kinds. Ask for the one where you don't need the filter, I think the inner layer is blue?

Inspect weekly or every infrequent use, replace if faults seen, or annually at least IMO.

Soap fittings for leaks monthly or ditto. Google for other maintenance tips, checklists, propane's one area worth paying close attention (boom no good)

 

[John61CT]

When fast output flow + cold tank temps ==> low vapor output, going to a two concurrent tank setup can help a lot. Warm temps change to one at a time w/ autoswitch, reg.

 

[Weight]

Propane must be very cold if it is affecting the vapor pressure. I used propane for heat when the tanks were below 0 F. I can't see the stove having a problem if the heat doesn't. You are feeding the stove directly from the tank with no regulator before the stove??

 

[Vagabound]

Propane must be very cold if it is affecting the vapor pressure. I used propane for heat when the tanks were below 0 F. I can't see the stove having a problem if the heat doesn't. You are feeding the stove directly from the tank with no regulator before the stove??

Agree with your first part. Everyone's talking about how cold might affect it, but in my case, nothing happened until it got hot outside. Like I already said, I don't suppose ambient temperature has anything to do with this specific problem. Plus, I should have mentioned that it is intermittent. The stove works fine almost all the time, and then every once in a while this problem will show up.

The connections go like this: tank, Mr. Heater hose, Mr. Heater filter, Coleman regulator, and finally stove.

Tom

 

[John61CT]

Not cold from the weather, but possibly from fast output flow from a too-small tank. Can freeze up the valves in 80° weather.

 

[hepcat]

Agree with your first part. Everyone's talking about how cold might affect it, but in my case, nothing happened until it got hot outside. Like I already said, I don't suppose ambient temperature has anything to do with this specific problem. Plus, I should have mentioned that it is intermittent. The stove works fine almost all the time, and then every once in a while this problem will show up.

The connections go like this: tank, Mr. Heater hose, Mr. Heater filter, Coleman regulator, and finally stove.

Tom

And... it could be that the regulator is getting ready to give up.  I've had to replace several on travel trailers over the years.  The ones produced today only seem to make it about five years.  I don't what's different about them from those produced in the '70s that would last nearly 30 years.

 

[Vagabound]

And... it could be that the regulator is getting ready to give up.  I've had to replace several on travel trailers over the years.  The ones produced today only seem to make it about five years.  I don't what's different about them from those produced in the '70s that would last nearly 30 years.

Thanks for the additional possibility, but in this case the regulator and stove are practically brand new. Been in use less than 3 months. And actually, that goes for all of the equipment I'm discussing, including all hoses, filters, tanks, etc.

None of that rules out a defective regulator. I've already had one of those on my first Buddy Heater. In this case though, if it was defective, we'd have to explain how it could be working right 95% of the time.

Tom

 

[Optimistic Paranoid]

One other thing to throw into the mix here.

We have a tendency to use the words LPG (For Liquid Petroleum Gas) and Propane interchangeably.  But LPG is actually usually a mix of Propane (with a boiling point of -40f) and Butane (with a boiling point of 32f).  Here in the states, the tendency is to go for mostly Propane, but in warmer climates a greater proportion of Butane is perfectly accepatable.  Canadian snowbirds who have spent the winter in Mexico report having problems when they head back to Canada and run into a cold spell, as the Butane won't boil and turn into a gas.

I wonder what you actually got in your last refill?

The Wikipedia article on "Liquid Petroleum Gas" covers this in detail, and in fact LPG can be mostly Butane rather than mostly Propane in some parts of the world.

https://en.wikipedia.org/wiki/Liquefied_petroleum_gas

 

[Vagabound]

One other thing to throw into the mix here.

We have a tendency to use the words LPG (For Liquid Petroleum Gas) and Propane interchangeably.  But LPG is actually usually a mix of Propane (with a boiling point of -40f) and Butane (with a boiling point of 32f).  ...

I wonder what you actually got in your last refill?
...

The sign said propane and it happened at one of the biggest propane filling stations in Quartzsite. So, my guess would be propane. But when they say propane, do they really mean that or maybe some sort of mixture?

Plus, there is the additional factor of ambient temperature. Again, mine was okay during cold weather and started having problems in hot weather. That seems to be the reverse of what everyone is predicting.

All of the behavior and information, taken together, lead me to suspect an intermittent clog somewhere.

Tom

 

[John61CT]

I at least was NOT talking about ambient temperature, but I give up on that aspect.

Sometimes contaminants get into a supplier's system, builds up over time in the customers' tank.

 

[Weight]

I would first test the stove by using a 1 pound bottle with out the hose. If the stove works with that, I would try a different hose or 20 pound bottle, whichever is less money for you. I would use an old bottle and exchange for a full. Like at a supermarket. In the USA, you can feel confident it is propane.

 

[Trebor English]

A couple of days later, something very similar happened, except that this time, the stove turned itself down, and then after about 2 minutes, it resolved on its own and the flame went back up.
Tom

For that to happen the gas pressure in the stove after the knob at the venturi that feeds the burner had to drop and then come back up.  The 14.7 psi ambient air pressure didn't drop and come back, it must have been the propane pressure.

A pressure reducer has 3 parts.  There is a valve that allows gas to pass through.  There is a diaphragm (think piston) that uses outlet pressure to close the valve.  The calibrated spring (pounds) works against the piston (square inches) to open the valve just enough to maintain the desired outlet pressure (pounds per square inch).  Since there are moving parts it can behave erratically.

The next time it happens use a wooden mallet (or spoon or hard plastic screwdriver handle or other multipurpose device) and whack the small reducer where the green tank (or hose) screws on to.  The knob valve probably isn't accessible for convenient whacking.  If the stove has two try lighting the other to see if the problem affects both.  If it only affects one, it might be a flaky knob valve.  Try picking up the stove a quarter inch and dropping it.  That whacks everything but would localize the issue to inside the stove.  The tank itself is less likely.  The over fill protection device and the valve that shuts it off if there is no appliance connected could be flaky.  Don't use a big tool to whack the top of the tank.  The same wooden spoon should be sufficient.

With electrical stuff you can put a volt meter on any part of the circuit to see what is going on.  With plumbing it is unreasonably hard to drill into the system and attach a pressure gauge.

 

[Vagabound]

For that to happen the gas pressure in the stove after the knob at the venturi that feeds the burner had to drop and then come back up.  ...

TE, thanks for the great reply and ideas.
I did the double burner test. They were both affected equally at the time that the problem was happening. 

Tom