Question on Propane Tank

[DutchmenSport]

This is my 3rd camper that has two 30 pound propane tanks. We've done a lot of cold weather camping over the past 20 years and in a way, we are camping now in "cold" weather. We're in Cullman, Alabama for another week and then heading home to Indiana.

This campground provides propane fill-ups and they sell by the pound. Now, I've filled at other places by-the-pound, but I'm noticing an oddity here.

Outside temps are ranging from 22 degrees at night to almost 70 during the day, depending on which day. We've been here for a month now and these have been the extremes. So, we are using the furnace for heat. So, we are using the furnace at night.

Now, back to the propane tank. One thing I've noticed here, when my furnace goes out and I switch over tanks (I open only 1 at a time), I've noticed ice on the bottom of the empty tank. The ice is formed about 2-3 inches high from the bottom. When filling the tanks at home, they are filled almost always, 6.9 or even 7 pounds. (Tractor Supply). Here, they are filling at 6.2 pounds. The guy that does the filling says my tanks are not emptying completely. But furnace is completely out, and absolutely no flame at the gas stove.

So, I'm a little bewildered. First, why is the ice forming on the tank? I've never seen that before until now. Like I said, we've had 5 different campers, pop-up, 3 travel trailers, 1 fifth wheel. Last 3 had 30 pound tanks, the ones before had 20 pound, and we've always had gas grills at home with 20 pound tanks. Never seen the ice before.

I'm sure there is a logical explanation, #1 for the Ice, #2 for a fill up at 6.2 (unless this is the limit the campground decided to go). It doesn't matter in the long run, 6.2 or 7, because it is paid by the pound. But still, if there is still gas in the tank.... why?

Any thoughts?

[jcurtis934]

The ice is due to having humidity at 99% here in the south. As to fill differences, the overfill protective device will limit the tank to 80% max if filled according to normal procedures. How the person uses the vapor release screw will change things. I have had tanks overfilled before, tanks with oil in the propane...both of which rv regulators hate.

[sourdough]

I suspect the ice is forming due to the reasons stated above. As far as the amount of LP, on my first fill of one of the LP tanks on this trailer the guy at the LP store said it was full of air and opened the vent screw to let it blow out for quite a while. When he was done he put in 7.1 gals.

[rohrmann]

His scale determines how much liquid he puts into the cylinder. He should be taking the empty cylinder weight stamped on the collar and adding the weight capacity of the propane, 30 lbs, and this is what he stops filling at. We full time, and have never closed one cylinder to run the other empty, that’s why there is an auto change over regulator so you never run out in the middle of the night. It’s possible that at the extreme cold temps, the remaining propane at the bottom of the cylinder isn’t vaporizing sufficiently, so you have maybe a gallon remaining, especially if it’s cold enough to form ice on the cylinder.

[DadsHemi]

It seams to vary who fills the tanks, I can tell you a 30lb bottle will hold 7.2 gals of propane but will be over filled and trip the overfill safety, I believe typically 6.8 gals is on an empty bottle when completely empty would be the norm. A few weeks ago here in Fort Smith AR it was 21 degrees in the early nights to early mornings and had a bottle run out, it switched over so I took the empty bottle to tractor supply and all that went into it was 5.6 gals. When the temps go very low the propane won’t boil off enough vapor gas to build enough pressure and thus that’s why the auto regulator will switch over bit yet propane it left in the other bottle. If your not using the or have an auto regulator it’s going to act empty.

[DutchmenSport]

Thanks for the replies everyone. I do have the auto switch over, but in my current fifth wheel and my last 2 travel trailers, I don't use it. I keep one tank turned off. Why? It only takes once to run out both propane tanks in the middle of the night, in a campground a bazzilion miles from the closest propane fill up on a Saturday night when there is snow on the ground.

Yep, after that experience, I said never again. Our first travel trailer did not have an auto cross over. I never ran out because I knew when one tank was empty. I knew I had some time to get the empty one filled now.

With the auto cross over, if you run out completely, you have no back-up, no warning, except a furnace that blows only cold air.

We're "relatively" cold weather camping right now, and I just don't want to wake up and be completely empty. I REALLY am not very good at checking the green - red monitor.

This last December (2020) at home, I filled one tank (we were using the camper at home) and put it back in place. It dropped even colder and we finally migrated back into the house. I knew the furnace was still on, about 45 degrees. Temps warmed a bit and thought we'd move back to the camper a few more night. Furnace wouldn't fire. Check the propane tanks and both were empty. Both were left "on" and the switch over did work. Took both tanks that same day to Tractor Supply for a fill up. I still do not know how both tanks were left on. But they sure ran through 60 pounds pretty fast that few days.

That's why I do one tank at a time.

[sourdough]

I have always left both tanks open because I detest one tank running out, always at the least inopportune, most uncomfortable moment leaving me to wander around in the dark, rain etc. to switch tanks. You do however need to watch the level monitor. When it's really cold I check it every day or 2 (takes about 2 seconds) because I can run through a tank in 3 days if using the furnace. Here in FL I check it about once a week and fill a tank every 2-4 weeks. I do use the heat pump for heating most of the time. As in most everything else; to each his own.

[Mstacksrazorbacks]

Dutchman where were you staying while in Cullman? I live in this area.

[DutchmenSport]

Originally Posted by Mstacksrazorbacks

Dutchman where were you staying while in Cullman? I live in this area.

Cullman, Alabama, Cullman Campground:

Click here

[bcrvman]

Originally Posted by DutchmenSport

Thanks for the replies everyone. I do have the auto switch over, but in my current fifth wheel and my last 2 travel trailers, I don't use it. I keep one tank turned off. Why? It only takes once to run out both propane tanks in the middle of the night, in a campground a bazzilion miles from the closest propane fill up on a Saturday night when there is snow on the ground.

Yep, after that experience, I said never again. Our first travel trailer did not have an auto cross over. I never ran out because I knew when one tank was empty. I knew I had some time to get the empty one filled now.

With the auto cross over, if you run out completely, you have no back-up, no warning, except a furnace that blows only cold air.

We're "relatively" cold weather camping right now, and I just don't want to wake up and be completely empty. I REALLY am not very good at checking the green - red monitor.

This last December (2020) at home, I filled one tank (we were using the camper at home) and put it back in place. It dropped even colder and we finally migrated back into the house. I knew the furnace was still on, about 45 degrees. Temps warmed a bit and thought we'd move back to the camper a few more night. Furnace wouldn't fire. Check the propane tanks and both were empty. Both were left "on" and the switch over did work. Took both tanks that same day to Tractor Supply for a fill up. I still do not know how both tanks were left on. But they sure ran through 60 pounds pretty fast that few days.

That's why I do one tank at a time.

You said you got up in the middle of the night to switch tanks. WHY? Use the auto switchover. You know how long the tanks last, if you need to, set a reminder on your phone to fill the tank. I have severe memory issues now at 78 and have never run out of propane in 40 years of camping. In cold weather the propane can not fully vaporize that is why some is left. Since the conversion of liquid to gas is endothermic that leaves the tank very cold and with some humidity it forms ice. Have you never used the trick to determine tank level of pouring water on the tank? As far as weight differences, there are lot's of reasons but if you are paying by the pound why worry.

[DebNJim B]

Originally Posted by bcrvman

You said you got up in the middle of the night to switch tanks. WHY? Use the auto switchover. You know how long the tanks last, if you need to, set a reminder on your phone to fill the tank. I have severe memory issues now at 78 and have never run out of propane in 40 years of camping. In cold weather the propane can not fully vaporize that is why some is left. Since the conversion of liquid to gas is endothermic that leaves the tank very cold and with some humidity it forms ice. Have you never used the trick to determine tank level of pouring water on the tank? As far as weight differences, there are lot's of reasons but if you are paying by the pound why worry.

Totally agree here. I cold camp all the time and check the gauge every day. When it's read I fill the empty one. No way I'm going outside in the middle of the night to throw a valve. I've run out only once in 8 years (that was before I checked every day) but no problem because the 20ob tank for the gas grill is my emergency back up.

[Daryles]

I have Mopeka tank monitors. Like you, I have run out in the middle of the night. Not fun.

[jcurryii]

Originally Posted by Daryles

I have Mopeka tank monitors. Like you, I have run out in the middle of the night. Not fun.

Mopeka too! I can monitor when one tank gets empty. Don’t want to run completely out in the middle of the night.

[Rlates]

I use the Mopeka Tank sensors with the app and thus far they have been very useful and accurate.

[Rlates]

I have used the Mopeka tank sensors with the app and thus far have been very useful. I have only had them about 1 month. But seem to be operating as advertised

[Slow Hand]

I don't have the auto switch but when I turn to my second tank I make sure to find a place to fill the empty tank. I never like being out of fuel. Another thing is when I do run out of fuel and my furnace doesn't light I always open the valve on the full tank before switching tanks. That way the system has max pressure when switching over. and my furnace always lights right up

[432bartman]

Do you guys run a propane gauge on both tanks? I didn't like not knowing where I stand with the amount left and put one on each tank.

[rohrmann]

Gauges on propane cylinders are worthless as they are very inaccurate. They can not gauge how much propane is left in the cylinder as they can only measure pressure and that stays pretty consistent until the cylinder is empty. If you absolutely need to know how much propane you have, the Mopeka system mentioned a few posts back would be your only option that will really work..

[richfaa]

We leave ours on auto switchover and have not run out of propane in 14 years. It takes like 5 seconds to open the door and look at the indicator.

[sourdough]

Originally Posted by richfaa

We leave ours on auto switchover and have not run out of propane in 14 years. It takes like 5 seconds to open the door and look at the indicator.

^^^^And this would be correct for us as well! I know how much I'm using due to varying situations and just peek in the door - might be once a day, might be once every 2 weeks, but I've never ran out of propane.

I bought the Mopeeka sensors and they didn't work for me. They sent me another set free - still no joy. I had another one brand new in the package when I sold the other trailer and bought this one. It's still there - I like looking and knowing vs the Mopeeka and wondering. JMO