Re: [A/S] Purging antifreze

[Charlie/Betty Burke <cbburke@xxxxxxxxxxxxx>]

Maurice,

Very few RV fresh water storage tanks have bottom drains. Airstream being one 
of them. The side drains are 3/8" above the bottom leaving several gallons of 
water which will over time evaporate or freeze. Since it is below any plumbing 
freezing will cause no damage. If however you dump RV antifreeze into the tank, 
what is left in it is a mixture. Read the fine print on a bottle of RV
antifreeze and you will see that one of the primary rules is "do not dilute" 
which of course is exactly what you do when you dump it into a typical fresh 
water storage tank.
So, dumping RV antifreeze in a fresh water tank dilutes it, a big no-no. 
Pumping it out of the tank will not get it all out, leaving a mixture. If it 
evaporates, adding water in the spring will bring the taste back out of the 
plastic tank walls. If it doesn't evaporate it will mix with the fresh water 
and still taste bad.
The manufacturer of Atwood/Bowen water heaters recommend blowing the water out 
of their heaters rather than letting it drain. The action of blowing it out 
scavenges the mineral buildup off the bottom and extends the life of the tank. 
We use 50 psi clean air to blow out each coach we winterize.
The size of drains in the black/gray tanks and the city water fill on the 
fresh water tank preclude blowing excess water out of the tank. Any water 
remaining in the tanks below the drain will not cause any damage when/if it 
freezes.

Charlie