Propane question for the engineers (appliances, house, water heater)

[bringselpup]

Last night I popped awake at 3am because I heard the furnace kick on. The oil heat hot air furnace I have on a setback thermostat at 58 degrees. So I stumbled out to the livingroom to see why and the propane gas log fireplace was off. Which was upsetting because I had put a fresh 100lb tank on it 3 days ago and it should have not run out for another 4 days at least.

Approx 30 days ago or so when I ran it I got 7 days out of a 100lb tank. This morning I switched in a 40lb tank to test the system and the fireplace works fine. And the 100lb bottle is hardly empty. I can feel the LP inside sloshing around.

I've obviously hit some plateau where last night the 100lb tank reached a point where what was left inside couldn't overcome it's liquid state and turn to gas. But why last night? I feel temps are clearly warmer than a month ago.

And any bright ideas to keep the bottles a little warmer?

[flycessna]

I think I am following you. However I am not convinced it is a temp problem. I had a propane tank for my grill that I could not run empty. But I had another tank that worked fine. I never could figure out what the problem was. I was told that My grill wasn't using enough gas. Ultimately I changed the regulator on my grill to get more BTU's Which I was going to do anyways, and I also replaced that propane tank. Since which I have not had any issues. And I am not sure what the real solution was....though I am inclined to think the tank was bad.

I do have 2 100 gallon tanks that I use for a monitor and an instant hot water heater. It never occured to me they could have the same problem. So maybe it is a regulator issue. Is it possible your not drawing enough pressure of the tank?

[forest beekeeper]

Assuming that your propane gas log fireplace has been tested and works fine.

Assuming that your 100lb propane tank still has fuel in it.

Is it possible that the fireplace pilot light went out?

[forest beekeeper]

Originally Posted by flycessna

... I do have 2 100 gallon tanks that I use for a monitor and an instant hot water heater. It never occured to me they could have the same problem. So maybe it is a regulator issue. Is it possible your not drawing enough pressure of the tank?

I have a propane flame thrower torch. When I mate it to one particular tank, it draws too much propane so the tank's internal mechanism shuts and does not allow flow.

Whereas I can swap tanks and it works great with other tanks. I just can not mate that one tank to my torch. I can use any other tank though.

So there is also a possibility of 'too much flow' causing an issue.

[bringselpup]

I have two 100lb tanks also, and the tank in question is the second of the two and not the one that I used earlier this year. So it is for now suspect. It was sold to me though in a package with a 200,000 btu construction heater. The gas log fireplace is only 30,000 btu. Theoretically that tank should not be shutting down on me. But I have only used the 200,000 btu heater in my garage connected to a 40 lb tank as I worked out there insulating the building and putting in a 10 foot strip of conventional electric baseboard heat.

This is the first time I've filled and used this tank since I've owned it.

I tried restarting the gas log last night and it wouldn't stay running which in the dim hours of the night led me to believe I had run out of gas. Switching to the 40lb that was stored in the garage this morning the fireplace lit on one try and has kept running. When I pulled the big tank this morning and found it wasn't empty I thought well maybe the thermocouple was bad but as I say, it lit right up when I switched tanks. Also the regulator being used is the one that came with the fireplace.

I too have had trouble pulling gas for grilling from a 40 lb tank but always in bitter winter cold. And as I was researching propane fired appliances before buying this gas log fireplace I ran across some threads on the net from pottery people who were discussing firing kilns with propane. They indicated propane suppliers were telling them that in some colder climates the 100lb tank wouldn't be big enough. Not because it might not hold enough gas, but because it might not be able to allow all of it's content to be released. There was some breakpoint between total volume in the tank and the amount that the tank would be able to release if it was cold.

So yeah maybe I have a fussy or defective tank. I guess one test will be to refill the original tank which I was planning on anyway before the weekend and hook it up. See if I get a full 7 days out of it like before.

[Northern Maine Land Man]

A tank is a tank. It has no moving parts. I believe you had a regulator problem. Maybe the vent to the diaphragm got some ice in it or something.

[bringselpup]

Originally Posted by Northern Maine Land Man

Maybe the vent to the diaphragm got some ice in it or something.

The whole setup, tank and plumbing was covered in ice. I had to chip it free just to swap tanks.

[forest beekeeper]

Older tanks were just tanks.

Newer tanks [which some propane dealers have been forced to be switching over to] have 'safety' mechanisms within the valve.

I have had to return one of the newer tanks once due to a faulty mechanism. And like now I have one tank that cannot be matched to my torch. But it supplies our kitchen stove nicely.

[ribbets]

Propane 101 - Promoting Propane Safety Through Understanding
under propane cylinders open OPD Valve

[Maineah]

I'm in Forrest's camp on this one. New tanks have the OPD (Overfill protection device) that will only allow the tank to fill to 80% capacity. It's like a float valve in the tank that shuts off the fill to allow some expansion room in the tank when it is full. Tanks that are over filled can allow liquid propane into the regulators freezing them. This will then allow liquid propane to enter the lines to the appliance and cause flareups as the liquid changes to gas in the lines. Sometimes these OPD's will stick in place and not allow gas to pass. Usually rocking the tank a bit will move the OPD out of the way. When they are really stuck you have to replace them.
Regulators also have vents in them to allow them to adjust to ambient atmospheric pressure. If the vents are plugged by water ice or frost on a high flow regulator these vents will plug and the results will be a slowing of the gas flow and a resultant orange flame. We have our 250 lb tank in a snowy area behind the house and even though it's fully covered I have to make sure it can always get air or our kitchen stove will run orange. 30,000 BTU's is about the size of two stove top burners running on our stove. That's not a lot of draw but more than enough for a 100 lb tank to continue making gas.
Get a new tank would be my suggestion.