Will Portable Propane Tank Work in Class A

In an emergency, can you hook up the little portable 15 gallon propane tank (like the one in your backyard hooked to the BBQ) to the main propane tank and heat your motorhome?

Most MHs have a fairly large propane tank that is permanently attached to the coach.  There is an add-on device that can be installed that will allow an external tank to be connected.  It can also be used to run a gas grill, lantern, etc. to be ran off of the MHs propane. 

The device George is referring to is called an "Extend-A-Stay".

It is quite versatile as he says, allowing external appliances to operate from the large MH tank or on-board appliances to operate from the external bottle.  I don't yet have one, but it's on my list.

rrfpacker said:

In an emergency, can you hook up the little portable 15 gallon propane tank (like the one in your backyard hooked to the BBQ) to the main propane tank and heat your motorhome?

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I have the extend-a-stay kit installed on my coach and use the small 5 gal. BBQ tank when in Yuma for months at a time. That way I can just disconnect it when empty and get it refilled and I don't have to unhook and move the M/H. Works great for me and during the summer I have a 12' hose I use to hook the big tank to my BBQ so I don't have to carry that 5 gal tank all summer.

Propane tanks are designed to be filled with 80% liquid and 20% gas to give the liquid an area to expand into, since propane is generally used in liquid form or in gaseous form and it is highly inadvisable to mix the use. If your effect is designed to work with propane as a gas, it is a very bad idea to attempt to run it as a liquid. This means that a 20# propane tank can hold more than 4 gallons of propane, but the safest amount is to fill them with about 4 gallons.

Common  20 lb.  RV Tank holds around  4 gallon.  It is like the one in your backyard hooked to the BBQ
The  30 lb.  RV Tank holds around  7 gallon

The small 5 lb. tank hold around 1 gal.
 

We have the Extend-a-Stay on our motorhome. We use it to hook up the Weber grill. When we were hosting in Death Valley, we had a Bbq size tank hooked up to it because it was easier to take it to town for refilling than it was to take the motorhome to town for refilling.

Wendy

Biker56 said:

Propane tanks are designed to be filled with 80% liquid and 20% gas to give the liquid an area to expand into, since propane is generally used in liquid form or in gaseous form and it is highly inadvisable to mix the use. If your effect is designed to work with propane as a gas, it is a very bad idea to attempt to run it as a liquid. This means that a 20# propane tank can hold more than 4 gallons of propane, but the safest amount is to fill them with about 4 gallons.

Common  20 lb.  RV Tank holds around  4 gallon.  It is like the one in your backyard hooked to the BBQ
The  30 lb.  RV Tank holds around  7 gallon

The small 5 lb. tank hold around 1 gal.

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Biker, not disputing any of your facts, but I'm having difficulty figuring out what practical lesson I'm supposed to learn from reading your post.

How likely is it that I have a dangerous mix of appliances (gas v/s liquid)?

I understand the difference, and application, of low and high pressure connections.  Is that what you were describing? 

Marshall Brass makes a couple of adapters.  For trailers with luggable bottles there is the "Extend-a-flow" This is basically a "T" connector.

One side is a male POL (or ACME now I'm not sure) the other is a female and the "T" is a "Quick Disconnect" (Identical to the top of those throw-away bottles) this comes in both straight through and right angle configurations.  There is nothing special about it. it's a "T".

The Extend-a-Stay adds a propane INLET.. Now I've seen knock off devices that.. Well, all they did was add a 2nd "T" for inlet.

The Marshall Brass Extend-a-Stay however does much more

It has the male POL, and the female to match the tank and regulator fittings on your Class A. it has the Quick Disconnect just like the Extend-a-Flow and it has an Inlet port. for hooking up an external tank. The hose is too short however (in my humble opinion) but that's easily fixed by any propane place.

Inside that cute little brass fitting is a pair of check valves.  This prevents gas from either the "main" or the "Aux" (External) tank from back-flowing into the other tank.. There is also an excess flow valve that shuts down the flow should a line break.> NOTE: This can cause problems when you first open the tank valve.. Do so very slowly to avoid them.

In short it adds to the rig's safety in many cases (Excess flow cut off) and versitility in all cases (Propane inlet and external tap)

One of my "neighbors" in the campground we are primarally staying at has a knock off.. It's just a T, no check valves.  Very dangerous since if you disconnect the aux tank gas is released from the main tank.

I too have a Marshall Brass Extend-A-Stay and agree with John that you want the added safety features that the Marshall Brass adapter contains.  I use mine to attach a 30# bottle for furnace and water heater operation while I snowbird here in FL.  As others have said, it is easier to take the external bottle for refilling than moving the MH and a whole lot cheaper than paying for LP delivery to the MH's main tank.

The adapter fits between your regulator and the main tank shut off valve.  Make sure you can move the regulator about 4 or 5 inches to allow for the adapter.

I also added an extra brace to support the regulator after I installed the adapter.  Before adding the brace I had one of my connections vibrate loose.

I have not had that happen (Connection vibrate loose) but then I tightened them down...

Very short story.. Back when I worked in roofing we flattened a tire.  Called the mechanic who bussed us out a spare. I got to change it.. Using only the lug wrench Ford bolted to the inside of the wheel well on the F-350 Custom I tightened 9 of the 10 lug nuts down (Broke stud #10)

Well. later we flattened that tire.. This time we were close enough to the tire shop the company had a contract with to drive in.. They called their mobile tire guy into the shop (they did not have a wrench in the store that fit the F-350 Custom) and he applied his rather large air impact wrench to the lugs I'd tightened by hand......

They did not move

(Took about 2 minutes of hammering to loosen the nut)

Like I said.. I tightened the fittings.

The extend-a-stay is the way to go.  I have been living in my 37' class A in Maryland since October and have not yet had to break it down to fill up for propane.  I have a 40# and a 30# bottle I rotate in and out so I never run out.  I had to have an LP plumber install mine because there was not much room to move the regulator he had to replumb some of the lines but on most applications you should not have a problem installing it.

I think I need to recheck the size of my tank, I could have sworn that I have a 30 Gallon tank, not a 30 pound tank.  When I go to fill it I thought I paid for 25 gallons a couple of times when I was real low.  It is a 35" class a and the tank is quite large.  I have never had a problem coming close to running out yet?  ???

mphy98 said:

I think I need to recheck the size of my tank, I could have sworn that I have a 30 Gallon tank, not a 30 pound tank.  When I go to fill it I thought I paid for 25 gallons a couple of times when I was real low.  It is a 35" class a and the tank is quite large.  I have never had a problem coming close to running out yet?  ???

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I'm sure you are right. I also have a 35' M/H with a 30 Gal. tank, but I use a 30 lb. BBQ tank hooked to it so that I don't have to move the coach just to fill the LP tank. I usually spend 5 months during the winter in Yuma, AZ. and also have never run out on the big tank. But this way I only have to fill the big tank once a year.

I can tell you a 5 pounder lasts me at least 2 nights when used as an external tank

However I now carry a 20 pounder for external use.. It currently has about 16 pounds in it.. The main tank has about 20 gallons in it though.

We have been able to get by on mostly electric heat.. My preference if I"m not metered.

I have 2 Deluxe Extend a Stays installed.  One feeds the propane generator and one feeds the other RV appliances.  My onboard tank s a 40 gallon and is reserved strictly for emergencies.  I use 40lb external tanks as I have found they are about as big as I want to lug around.  Portable proane tanks can be picked up cheaply on Craigslist is you just keep an eye out.  I have been at the current,  very remote jobsite for 50 weeks and have not had to pull out once to refill the onboard propane.

More here
http://www.myoldrv.com/?p=59

mphy98 said:

I think I need to recheck the size of my tank, I could have sworn that I have a 30 Gallon tank, not a 30 pound tank.  When I go to fill it I thought I paid for 25 gallons a couple of times when I was real low.  It is a 35" class a and the tank is quite large.  I have never had a problem coming close to running out yet?  ???

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Quick conversion is 4.25lbs per gallon of propane.  If you have a 30 gallon tank it will hold roughly 120 lbs.  That varies depending on temperature though.  Also as others have mentioned they only fill them up to 75% of capacity.  I am living full time in Maryland right now and on the coldest days (highs of 20 degrees) have been using 10lbs of propane a day for the heater set at 58 at night and 50 during the day.  The electric is metered so space heaters would be expensive.

Biker, not disputing any of your facts, but I'm having difficulty figuring out what practical lesson I'm supposed to learn from reading your post.

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My post was for the OP. 
Lesson was his Quote: "little portable 15 gallon propane tank (like the one in your backyard hooked to the BBQ)"
It is more likely to be a 4 gal gal. 20# tank and not a 15 gal. one.