Thursday, December 4, 2014

It's a gas

We had black and gray water, fresh water, electricity that's got to be it then??
Well no. RV's use propane gas for a few things too. Propane is that stuff in the gray bottle under your barbecue that cooks the steak until it's black and crunchy and even the dog won't eat it.

Propane is a gas. A flammable gas. An explosive gas. An asphyxiating gas. Pretty dangerous stuff if you let it be. Propane when burned as a fuel gives out Carbon Monoxide, an odorless asphyxiating gas. So please make sure your rig has a propane leak detector and a carbon monoxide detector as well as at least one smoke detector and that the batteries in all these devices are changed regularly. Your birthday or a holiday would be a good time to change the batteries every year. That way you might remember to change them.

Back to the gas.

Our rig has a 30'ish gallon propane storage tank underneath on the right side. 
The propane tank under the rig
When we want to fill it we go to a station that has a big propane storage facility and a loading station for RV's. 

The technician brings out a hose and couples it to the rig then fills up the tank. 

We have found that a fill will last all year the way we have been camping but that will probably change when we get full timing.

There is a valve on the tank controlled by a solenoid. When the solenoid is open propane goes out to the rig. If the leak detector senses a leak it will close the solenoid. If the coach battery is off the valve closes. I like that, I think it's safer.

Propane in the rig is used for several things. The obvious one is the stove/oven. Less obvious is the heating system and the water heater. Not at all obvious is the refrigerator.

How can burning propane make something cooler?? Well RV refrigerators together with boat refrigerators and refrigerators for use where there is no electricity (Amish communities and parts of Mexico), don't use the same system as electric refrigerators to cool your beer. 
Want me to explain the refrigeration cycle? 
I didn't think so but I'm going to anyway!! When a material changes state from say a liquid to a gas or a gas to a liquid a large amount of energy is used to make the change. We supply the energy to compress freon gas (Or some similar material) which when cooled turns to a liquid. If we let the liquid expand it absorbs a large amount of energy as it turns back from a liquid to a gas. That expansion is used to absorb the heat inside a refrigerator. 
RV refrigerators use a different material usually ammonia and use heat to boil the ammonia which turns it into a gas, (it's similar to boiling water and watching it turn to steam). When the gas cools it turns back into a liquid and absorbs heat as it does so. We use that to cool our RV fridges.

Lecture over. 

But there are some disadvantages to using ammonia as a refrigerant. The one that affects RV'ers most is the need for the fridge to be pretty level when it's working. The reason for that is that the liquid refrigerant flows back to the "Boiler" at the bottom of the fridge by gravity, down sloping pipes. If the fridge is very out of level then the liquid doesn't flow down to the boiler and the boiler burns up thru being empty. Big deal? If you ever have to buy a new propane fridge then you'll suddenly realize that it IS as big deal. A couple of thousand dollars worth of big.

The heating system is rightly called a hot air heating system in that the propane heats the air and a fan distributes it thru the rig. Nothing big there but ensure the outlets and the return grille aren't obstructed or you might shorten it's life.

The water heater is pretty easy, the most important thing is to replace the anode in it once every year or so. The anode is a metal rod that rots out slowly and sacrifices itself to save the water heater tank from rotting out. If you never check and replace the anode then when it's rotted completely away the water heater rots next and you get a nice big bill for that instead of a small one for an anode.

I won't say much about the stove/oven not much to go wrong there.

Maybe you have one of these? 
A Coleman Road Trip grille

They run on these...
1 lb Propane Bottle

They cost a lot for what little gas they hold but what else can you do? If you want to, you can buy a hose and adapter that will let you run on a big bottle like this.

Another thing you can do is buy an adapter that lets you refill the small bottles from the bigger one. Sounds interesting? Well if you want to get a useful amount of propane in the small bottle you need to put it in the freezer for a couple of hours first. When it's good and cold screw the adapter onto the big bottle (It's a left handed thread). Screw the cold bottle onto the other end of the adapter, INVERT the big bottle and turn on the valve. Let it fill for 1 minute, turn the valve off on the big bottle and unscrew the small bottle. I've discovered that if you then re-freeze the small bottle you can get a big charge in it the second time you fill it. I'm not sure why but it works for me. It works best if the big bottle is nearly full. Best of all instead of $5 for a full bottle in the camping store it's costing around $1 to fill from the large bottle. I have about 6 small bottles that I rotate from the garge to the rig.


Now you are a propane system expert.
Take notes there may be a test later.

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