HomePropane Management

Hot Water and Hot Air and Cold

You heat the RV and your water with Propane.  You cool the refrigerator with Propane.  Each of these is a separate issue but the primary concern is your propane tank.

Propane -- Low Pressure Gas

Propane sells for anywhere from $1.00 to $3.00 per gallon.  Propane is expensive.  I have seen it as high as $3.00 per gallon.  Do not confuse pounds with gallons.  A gallon of propane is about 4 pounds I think.

In some southern states butane replaces propane.  For non-chemists, they are the same and they are invisible.  A fragrance is added to let you know when you have a leak.  If you like the smell, you have brain damage.

Here is the skinny.  Propane becomes a liquid when compressed or cooled.  This is true for all gases but is meaningful here.  Your tank contains mostly liquid propane when full.  The remainder of the tank is filled with propane gas.  When the pressure is released or the temperature rises, more propane reverts to gas.  The gas expands to fill the available space.  At some point the pressure of the expanded gas keeps the remaining gas compressed as a liquid.  This is a lot of pressure.  This pressure makes the gas go into your gas lines to the appliances.  The reason that “full” means 80% of the tank volume is that a buffer space for equalization is necessary or liquid may force up the line.  Liquid in the gas lines is bad.  Real bad.

Pressure Relief Valves

Most of us are familiar with the flat, gray, circular, attachment on your home or RV gas line.  This is a pressure relief valve.  When the expanding gas has no place to go and builds up in the tank, this valve releases to the outside air.  Sufficient gas is released to keep lines and tanks from exploding.  There is a reason that the tank has round ends and made of serious steel: this gas pressure is high even though it is called low-pressure gas.

One of my stories.  Once upon a time I had a Dodge van with a 2-gallon tank mounted on the undercarriage.  This fueled my refrigerator and space heater.  Neither the attendant nor I knew the rules of propane filling and the tank was filled to the top.  Because his valve was smarter than we were, it stopped when it should.  We manually overrode it to get the full 2 gallons.  Serious mistake.  All the way down the mountain we heard the relief valve letting off propane.  In an RV or in your 5th wheel or in your trailer, the tank is a long distance from any flame.  In my van, the tank was close to the rear axle.  This meant that it was near my brakes and we were driving down the mountain.  I was afraid that the brakes would spark (they do you know) and the spark would ignite the escaping gas.  It was not just the valve that was relieved when we reached the bottom of the mountain.

Why was the gas expanding?  Gas compresses to a liquid when it reaches a certain pressure.  The critical pressure increases with temperature.  As the temperature in my tank increased, the amount of gas increased.  This resulted in a higher pressure gas.  When that pressure exceeded that of the relief valve rating, the valve opened to let off the excess gas.  Releasing gas to the outside air is dangerous but less dangerous than an exploding tank or gas line.

You know, I am really lucky to have lived to retirement age.  This gas system is one I created.  It had no external relief valve.  The gas was releasing through the fill-relief valve.  Be smarter than I was: make sure your system has a good relief valve.

Fill-Relief Valve

On the side of the RV tank is a Fill-Relief Valve.  This is a dime-sized knob – sometimes with a hole through it.  When filling, this valve is opened until you hear gas escaping.  The tank is then filled while you hear the hissing.  When the liquid reached the “full” level, this valve spurts liquid.  You turn off the fill and the relief valve.

LP -- Low Pressure Gas System

The LP gas system is composed of a tank with an external fill and copper tubing to the water heater, the refrigerator, and the furnace.  Immediately after the tank and before the tubes wonder off, there are a couple of valves: a pressure relief valve and a cutoff valve.

Propane Tank

The tank is contained in one of the side compartments.  This compartment should not have a lock, as emergency access is critical.  In an RV, the tank is usually horizontal and permanently installed.  Many 5th wheels have a compartment with one or more “portable” containers.  We are all used to seeing travel trailers with a couple of bottles mounted on the hitch at the front of the trailer.  Some states require you to display a haz-mat 1057 sticker near the tank.

OPD – Overfill Protection Device

If your tank is portable, make sure your tank has the OPD marking on the handle.  As of April 2002 dealers cannot refill the old tanks.  Many people are angry with this but the rule will not be reversed.  The OPD has a valve that closes at 80% of the rated tank capacity.  This is good but it means your tank is really 80% of what is says it is: a 25-gallon tank will be full at 20 gallons.

Built-In and horizontal tanks have had an OPD for a long time.

Filling the Tank

Keep your tank full.  Watch them fill it.  Watch them reset the meter to 0 before they start to pump.   Many people think that all RV people are rich -- some lowlife take affront that you are not willing to share the wealth.  Amazing.

Propane sells for anywhere from $1.00 to $3.00 per gallon.  This is expensive.  Keep you tank full.  The OPD valve closes at 80% capacity.  This is good but that means your tank is really 80% of its stated capacity.  On the other hand, propane tanks have always been 80% capacity and it is now enforced.

Prepare to fill:

The first time I took the RV out, I went to the Kmart in Show Low, AZ.  In the same parking lot about 150 from my RV was a good-sized Winnebago.  When Bree and I came out of the Kmart and got into our RV, I thought my window had a problem as it was black.  I turned around to see the Winnebago turn into a torch.  The sirens started as the fire department was literally next-door.

They made no attempt to stop the fire.  They just kept people away until it died.  We left before then.  We returned the next day to find spots of melted metal on the concrete.  In other words, this RV went from looking normal as we stepped into our RV to literally being a torch with nothing of value left in less than a minute.  This turned out to be a propane leak into the inside the RV.  I have met too many others with similar stories.  Do not mess with propane.


Your furnace runs off propane.  It consumes a lot of propane.  Use the heater sparingly or live near the propane dealer.  Many new RVs are coming with heating strips that run from the 110v.   Parks hate this as they pay a lot for their electricity.  You can add heating strips to the inside of your AC or you can go cheap like me and have a couple of space heaters.  If you get space heaters make sure they have multiple heat settings, a thermostat, and safety cutoffs.


A gas-powered refrigerator cools much more slowly than the refrigerator in your standard kitchen even when switched to AC power.  You must keep the louvers in the rear of the unit clear of ice.  Periodic defrosting in damp climates is necessary both for the refrigerator and the freezer.


Outside under the vent cover here is a thermister that detects flame.  If the gas attempts to light and fails or the flame goes out, the thermister will close and the igniter will attempt to relight the flame.   A thermister is about $25 and is easily replaced.  It is under the little metal cover held in place with one screw and located near the gas line entry.


If the igniter fails, there is no spark when the thermostat says that it needs more cold.  The cost is about the same as the thermister.  You can see if the igniter is working by looking in the gas tube for a spark.   It also may make noise when it sparks.

Twisting the outside black latches 90 degrees and then pulling the cover away from the wall will remove the standard vent cover.

A small box of baking soda inside the door and changed every couple of months will keep your refrigerator fresh.  I buy about 6 of these and stock them.  I usually forget to change them on schedule.

You can locate web pages to inform you of how a little gas flame will cool the refrigerator.   Interesting.  The one requirement is that the gas-powered reefer must be kept almost exactly vertical to operate properly.  If you are level and yours does not work properly there are a few easy things to check.  See the Care section for refrigerator care.

The refrigerator is set up to run from propane, 110v AC, 12v DC, or a choice of multiple of these.  My Dometic will run from propane or 110V AC.  It defaults to the 110v and will switch from propane when it detects AC power.  It automatically reverts to propane when the AC power is removed.  Mine does not operate from 12v DC that I can determine.

Fans and Special Care!!!

Your RV refrigerator is designed to run on gas/propane.  When used with electricity, it has a heater element to replace the gas flame.  The internal gas is ammonia.  If you smell ammonia, turn everything off, use an ice box.  You will need a new cooling unit (probably).  Your home refrigerator works on FREON (Or whatever they call it these days) and uses a very different transfer mechanism.

This means that your RV reefer is more fragile and more sensitive to heat than your home reefer.  It also has less insulation.  In other words, the RV refrigerator is like nothing you have used before and is not really your friend.

First off, ANY refrigerator works better when full than empty.  THis holds especially true for the freezer.  I keep water bottles to fill otherwise empty space.  Water bottles serve multiple purposes but in this case I refer to them as my "Cold Bank".  If your gas or electricity fail, these will keep the rest of your food cold for days.  The door of your refrigerator acts like a large vacuum cleaner: when you open it, ALL of the cold air leaves the refrigerator and more gas/electricity is needed to replace the cold air.  Less cold air (larger cold bank) means less work for the refrigerator.

It get s worse.  In your RV refrigerator there is nothing to cycle the cold air.  You will get hot and cold spots.  They sell little fans ($15) to help with this.  If you do not mind opening money for a couple of batteries every month, this is fine.  Me, I went to Radio Shack and bought a 12V computer fan ($15). I attached this to the door light mounting (before the on/off switch!) and now the hot spots are gone and I do not have to remember to change the batteries

It gets more worse.  If you live in a very hot climate as I do, the outside rear tubing does not have a sufficient temperature differential to the air to permit the heat transfer.  So you will at least overheat your unit and get no cooling.  Overheated units have been known to break the ammonia seal.  They sell ($40) a little fan with a thermostat and is somewhat weatherproof to fit inside the cover door and blow air on the tubing.  I bought a $6 fan at Wal-Mart with an on/off switch (it is ALWAYS hot in the summer).  I might worry if it rains but in the meantime, I have solved the overheating tubes problem.

Condensation Switch

Like some home reefers, there is often a heating element around the seal on the freezer and reefer doors.  This heating strip is concealed but runs when the reefer is on.  This prevents moisture buildup.  Mine has a switch near the door seam.  I keep the switch off unless I need to clear the water (humid climates).  Keeping it on will consume electricity.  You may not notice this on park AC but it may be a problem boondocking.

Water Heater

Camping World has little screen covers for the exterior heater vents: these are a good idea in any place that has bees.

If you are going to travel to remote areas, buy an extra relief valve.  Sooner or later you will need one.

Every couple of months, drain your heater.  Calcium and other things build up inside similar to your home heater (which should also be drained periodically).  Since your water supply is not as reliable as your old city water, keep the heater clean.

I am cheap.  I run my hot water heater only when I am planning to use it.  Many people run it all of the time.  This uses a fair amount of propane. 

Electric Conversion

You may buy an electric conversion rod so that your heater runs off of 110v – park power. 
These cost about $100 and fit into the water heater drain valve. 
If you buy one, make sure it comes with its own thermostat. 
Also check the length of the rod.  There are short ones and long ones.  If in doubt, measure the depth with a tape measure.  If the measure hits anything before the long length, buy the short rod. If still in doubt, buy the short one.  Many water heaters are not very deep and the long rod will not fit the depth/width of the tank.
Electric Heater Conversion rods are like your refrigerator in terms of park unfriendly: see Park Power Connections.

Gas Range, Oven

These use propane like any other gas-cooking appliance.  I like to cook with gas.  Some of the higher end RVs now come with a convection oven in place of a microwave and a gas oven.  Shame on them.  When using your range or oven, make sure you keep the vent open and the fan running.  Even when it is cold.  When you cook, all sorts of oils and grease are released to the air.  So is smoke if you are not careful.  Make sure you have enough ventilation to get this outside quickly as your walls, blinds, carpet, and ceiling are all capable of absorbing it.  Without sufficient ventilation you will have a very smelly RV.

The RV Makers Are not Your Friends.

Remember, the companies that make motor homes do not care at all if things are energy efficient.  Maybe that will change but I sincerely doubt it.  The refrigerator could have more insulation.  It could come with small built-in fans.  It could do things I have not thought of.  But their profit margin would go down and these are things that the casual traveler would never notice.  And you do not pay the electric bill separately at the RV parks.

My two little 4-amp 5000 BTU window AC units produce more cool air than my 17-amp roof unit that came with the RV. This means that for half the electric cost I get more cool air.  I do need a fan to move the air from the front to the back.  Why? Because they can.  The RV maker could care less about your electricity usage.  When I move, I just lift out my little window units and hide them under the bad along with the spare I keep if anything should happen to the first two.  Spare?  The things with an exceptional EER rating cost $100 at Costco.  Just to have someone look at my roof air costs $250.

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Written:  2003                 Updated:  June 10, 2010                 Back To Top