Originally Posted by toskeysam
Another, more colorful, solution suggested using cheap vodka......hmmmmm vodka on tap so to speak. ( can you say flammable?)
Alcoholic beverages are only flammable if they are 100 proof or higher. Your basic cheap 84-proof vodka will not burn (except on the way down your gullet).
Living in the south, last year I had to winterize my Interstate five times, because every time I winterized, I ended up going camping again. I'm not complaining; that beats winterizing once and letting it sit all winter! Anyway, I'll share my sequence:
1 - Before you open the drain plug on the bottom of the fresh tank, drain the tank by opening a faucet and running the pump until it sucks air. I did this by turning on the shower and holding the nozzle over the toilet to give my black tank a thorough rinse. Since you have to lie on your back on the ground to open the drain plug, if the tank is nearly dry to begin with, less water runs out on the ground to get you wet.
2 - Open the drain valves on the fresh tank first, then the water heater. Also open the pressure relief valve on the water heater so it drains faster.
3 - Open the low-point drains and then open the faucets (with levers midway between hot and cold. Also flush the toilet to drain the line running to the toilet.
4 - Drain the black tank and gray tank, with the discharge hose pulled completely off the reel and laid out flat. Run the macerator pump until it sucks air as well.
5 - Using a blow-out plug, blow out the black tank flush fitting. If you've used it at all, the check valve on the flush fitting retains water and will freeze otherwise.
6 - Partially fill the black tank and gray tank with RV antifreeze. Open the black tank valve and let some of the antifreeze run down to the macerator pump. Pump out just enough antifreeze to see pink stuff in the discharge hose. Close the drain valve and add more antifreeze to the black tank. Also add a little to your toilet bowl to wet the seal, and cover the toilet bowl with Saran Wrap if you intend to drive the Interstate while it's winterized, to keep pink stuff from sloshing out.
7 - Hook up your external shower hose.
8 - After washing the blow-out plug (it was
just hooked up to your black tank) hook it up to your municipal water line. Close the low-point drains but leave the faucets open. Also open the water heater bypass valve.
9 - Blow out the lines, including the external shower.
10 - Remove the external shower, close the faucets and the water heater pressure relief and drain valves, done.
That's all I do. I don't fill the water pump with antifreeze because it's inside the van and has been run dry to minimize the amount of water left in it. But then again I live in the south, and even when temperatures drop below freezing they don't usually stay that way for even 24 hours in a row. You might want to disconnect your pump as a final step since you live in a colder climate. But don't winterize the pump. Since you've got it disconnected anyway, just insert a golf tee in the inlet and outlet lines to plug them, and take the pump indoors to store it until you're ready to hook it back up.
I don't think I've forgotten any steps, but if I have, I'm sure someone will chime in. Luckily an Interstate has Hevpro valves on the sink and shower drains, not P-traps, so you don't have to worry about filling P-traps with antifreeze.
On edit, since there have been other posts while I was writing this, the air pump I use to winterize produces 60 psi (regulated, from a 125-psi 1½ gallon air tank). I have no shortage of compressed air, so I don't need the "leave the faucets closed to build up pressure" trick.