Another towing weight issue

[Flametheus6]

The book says that water weighs 8.3 lbs per gallon and that the fresh water tank is 61gals. It also states that the hot water tank is 10 gals. If I fill my fresh water tank before heading out does that mean I actually have 71 gals of water? Doesn't it auto fill the hot water tank first? I don't plan to be so close it would make a difference I just like knowing these things. I thought the manual for my BETA tape system was difficult!!!

[Flametheus6]

The book says that water weighs 8.3 lbs per gallon and that the fresh water tank is 61gals. It also states that the hot water tank is 10 gals. If I fill my fresh water tank before heading out does that mean I actually have 71 gals of water? Doesn't it auto fill the hot water tank first? I don't plan to be so close it would make a difference I just like knowing these things. I thought the manual for my BETA tape system was difficult!!!

[RustyJC]

Assuming you start off with both the fresh water tank and hot water heater tank completely dry, you would put 61 gallons of water in the fresh water tank. Nothing would flow to the hot water heater tank until (1.) you turned on the water pump and (2.) opened a hot water faucet to allow the air to escape. Even then, there will be an air space in the top of the hot water heater tank to allow for expansion.

So, you would then have (let's say) 50 gallons in the fresh water tank, 9 gallons in the hot water heater tank and 2 gallons in the water lines and gray water tank (from bleeding the air out of the hot water heater tank). You could then refill your fresh water tank with 11 more gallons.

Interesting mental exercise....

Rusty

[Fulltimer]

Sometimes the specs on the water capacity includes the water heater. (makes it sound like more than it is)

[Flametheus6]

Thanks, great detail and balanced answer so now I either do or don't have 71 gals. Philosophy is great. How about this. I have two 30gal propane tanks according to the manual they hold 7 gals each at 4.3 lbs a gal. Why does a 30gal tank hold 7gals?

[RustyJC]

Well, on the fresh water tank issue, you could tell if you didn't get 61 gallons in the tank on the initial fill. If you only managed to get 51 gallons or so in, then you know that the other 10 are based on the hot water heater tank.

At 7 gallons x 4.3 lbs/gallon, you'd have 30.1 lbs of propane - about right for a 30 pound cylinder.

Rusty

[450Donn]

Hot water tank is always filled from the fresh water system. It will not fill until you do one of two things, 1) put a hose connection on the city water inlet and turn it on, or 2) fill the tank and turn on the water pump. At which time it will pump water out of the tank and fill the W/H, and drain 8 or 10 gal from the fresh water tank.

[Ray,IN]

When calculating the total weight of propane you are hauling remember, the tanks will only accept 80% of total volume. So, multiply a 30 pound tank X 80% = 24 pounds actual capacity of a "30" pound tank. 24 divided 4.24 = 5.6 gallons of propane.