Propane supply

[DennisB]

Hi. We are on first extended trip in our new 2020 trail manor 2720QD.
Last night the propane ran out so I went out front of the trailer and flipped the lever that says “supply” over to the other tank and there was no propane in it either. So apparently both tanks had drained. Very inconvenient on a chilly night.
Today, I got the tanks refilled and reinstalled them. Turning only one tank on, I put the supply valve in several different directions and it made no effect on the flow of propane into the trailer. So I can only assume that this valve either doesn’t work or is simply for decorative of purposes. Because the dinette part of the trailer extends out over the propane tanks it’s a bit of a hassle to change the tanks on short notice like late on a rainy night or something like that.
For the time being I will just turn one tank on and when it has drained climb underneath the trailer and turn the other one on by hand. It’s a little uncivilized and I’m looking for a better solution.
Any suggestions would be appreciated. Is there any add-on propane level monitoring systems that work well? (The little gauges on the tanks don’t seem that accurate)

Thanks,
Dennis

[Bill]

Dennis -

Hmm. The picture shows that there is gas at the regulator - the indicator is green. It shows that you have the tank on the right selected - the switch is pointed to the right. And the gauge needle on the right tank is pointing straight up, which means the right tank is about half full (be sure to read the upper half of the gauge, labelled HORIZONTAL, since your tank is lying down). All of this says that you should be getting normal propane flow.

I think of two possible sources of problem.

First, the green knob may not be screwed on tightly. Buried in the middle of the green knob is a pin, and when you screw the knob onto the tank valve, the pin depresses a gas release valve in the tank valve. If you don't screw the green knob tightly onto the tank, the pin won't depress the release valve, and you get no gas flow. I have a couple tanks like this in the BBQ at my camp (that's Maine-speak for cottage). So grab that green knob firmly in your hand, lean into it, and crank it down as tight as you can. Don't use a wrench - you don't want to break it. But get it as tight as you can by hand.

Second - and I think you know this - if you open the tank valve too quickly, you can trip a safety valve called an excess-flow valve. This device is meant to cut off flow if the gas hose is cut, for example. But if you open the tank valve too quickly, the CHUG of gas into the hose can trip it. So close the tank valve, wait 15 or 20 seconds, and then ease it open.

We'll talk about gauges in a separate post. For now, try these things. Hope they work.

Bill

[DennisB]

Hi Bill, I took the photo of the tank immediately after getting it filled this morning so, yes there is gas in it now and it supplies gas to the trailr-my question was about that supply lever in front of the tank. I was told that you use that lever to select which tank is being used and when one tank runs out, to just switch the lever over to the other side to start drawing gas from the second tank-after getting the tanks refilled this morning, I tried to use the supply lever to direct which tank to use and it had no effect.

So my question was “does the supply lever allow you to select which tank is being used?”

Thanks,Dennis

[Bill]

You asked about propane gauges. There is a lot of misunderstanding - and wasted money - in this question. Bear with me.

In a tank, the propane is stored as a liquid. Like all liquids, it evaporates, meaning that the liquid propane changes to propane gas. The gas (vapor) takes up more space than the liquid, so the pressure in the tank rises. For propane, when the pressure in the tank reaches 145 psi, the liquid can't evaporate any more, so the process stops. Then, if you draw off some of the gas to run your appliances, the pressure in the tank drops, and more liquid evaporates until the pressure rises to 145 psi again. This cycle continues until the tank is empty.

The important thing to realize here is that the pressure in the tank is always 145 psi, regardless of how full the tank is. So the pressure in the tank doesn't tell you how much propane is in the tank.

If you go to Amazon and put in "propane pressure gauge", you will see dozens of gauges, and they all measure pressure. In other words, they don't tell you how much propane is in the tank, and if you buy one, you are being cheated.

So how can you tell how full the tank is? There are a few ways, none quite as handy as the "magic" but useless gauge.
1. Weigh the tank. The math involves the weight of the tank and the weight of a gallon of propane, so it is kind of unhandy, but it works. To make it simpler, many propane BBQ grills have a spring-loaded hook on the side. You hang the tank on the hook, and the more propane there is in the tank, the heavier it is, and the more the pointer moves.
2. Have a gas technician install a float gauge in your tank. This is a more accurate version of the gauge that the tank already has.
3. color-changing strip. You glue a strip of special plastic to the side of the tank. The plastic changes color when the temperature changes. Since the temperature of a tank is slightly different where the tank contains liquid than where it contains gas, you see the amount of propane by looking for the place where the color changes. Advantages - much cheaper than a magic gauge, really works, no math. Disadvantage - in some conditions, you have to throw a cup of warm water on the tank to highlight the temperature change.
4. Electronics - There are electronic devices that you attach to the tank. They usually use ultra-sonic sound to locate the top of the liquid. Disadvantage - expensive. Advantages - like the gas gauge in your car, it has a simple-to-read gauge from empty to full. You can put the gauge anywhere you want, such as inside your trailer.

So why do I go through all this? In hopes that you don't buy an expensive "magic pressure gauge".

Bill

[Bill]

Originally Posted by DennisB

Hi Bill, ... I was told that you use that lever to select which tank is being used and when one tank runs out, to just switch the lever over to the other side to start drawing gas from the second tank-after getting the tanks refilled this morning, I tried to use the supply lever to direct which tank to use and it had no effect.

So my question was “does the supply lever allow you to select which tank is being used?”

Dennis -

The short answer is yes, it allows you to use the lever to select which tank to use, if you want to do that for some reason. The part that you may be missing is that it doesn't require you to select a tank in order to use the gas in both tanks. The system will draw gas from whatever tank the lever is pointing to, until that tank runs out of gas. When that happens, the system automatically switches to the other tank. You don't have to do anything - you don't have to move the lever.

So assuming both tanks have gas in them, you just turn on both tanks. The system will draw from one (the one the lever happens to be pointing to) until it runs out, and then will draw from the other, with no need for you to move the lever.

Eventually, at a time that is handy for you, you will want to remove the empty tank so you can have it filled. At that time, you move the lever to point to the tank that still has gas, and now you can remove the empty one. But you do this at a time that is handy for you. You don't have to deal with anything in the middle of the night.

Bill

[Bill]

An example may help. Suppose that it is going to be a cold night, and each of your tanks is half full You know that a half-tank won't get you through the night, but three-quarters of a tank will be enough. Do you have to worry about getting out of bed in the middle of the night to change the lever? No. You simply point the lever at either tank - your choice - turn on both tanks, and go to bed. In the middle of the night, the first tank runs out of gas, the second tank takes over, and you stay warm all night.

Next day, when it is convenient for you, you can get the empty tank filled.

The only way to make this fail is to turn off one tank. In this case, when the mechanism tries to change over to the other tank, it can't. You turned the other tank off.

Bill

[commodor47]

Dennis,

Perhaps this video will help in understaning how the automatic propane LP Changeover/Selector Valve Works.

https://www.youtube.com/watch?v=wmxDfwCuLnk

The key is to make sure you have the inactive tank valve open so when the active tank (which the selector valve is pointing to) runs out of propane, the valve automatically starts drawing gas from the other tank.

Dick

[DennisB]

Ok, thanks everybody. I was hoping for some kind of system that lets me know when the first tank empties so I can put a tank refill on my to-do list and not get stuck with two empty tanks at an inconvenient time.

Thanks again
Dennis

[Shane826]

It does let you know you have an empty tank. Open both tanks. If the lever is pointed right, then it is drawing from the right tank. The indicator will be green, meaning gas is flowing from the tank the lever is pointed towards. When that tank runs out, the internal mechanism switches to the left tank and gas flow is uninterrupted. BUT the lever does not flip to the left tank. It is still pointed to the right, and the indicator is now red, showing there is no gas flow from the tank that the arrow is pointed to. You flip the lever to the left, the indicator now turns green because there is gas flow from the tank the lever is pointed to. Remove the empty tank, refill, reinstall, and open the valve. Now when the left tank runs out it will automatically switch to the right tank.

I made a video of this but I don’t know how to post a video here.

And yeah the slide models make it pretty inconvenient to fill a tank mid-trip.

[DennisB]

Shane,
Thank you! That is exactly the information I needed-now the system makes sense to me.

Thanks again,
Dennis