Here's two videos on this subject that will give you some pointers in general:
HERE'S HOW I WINTERIZE MY COACH
* It will take 3 gallons, but it's safe to have 4 gallons of anti-freeze on hand.
* If you don't hear the pump or if you loose pressure, you know your gallon anti-freeze jug just ran out. So it helps to have a second person; or I suppose you can start with a 3-5 gallon container of anti-freeze; or you can plan on making several tank swaps.
* I DO NOT purge the system with air because you want to keep the pressure in the lines. This reduces the "spits" of air in the line when winterizing with your 12V pump.
* I DO NOT empty the hot water heater until the last step, because I want to keep the pressure in the hot water line until I am ready to deal with the hot water purge.
* I DO by-pass the hot water heater before I start purging the cold water side.
*** I follow this purge-order, because all my faucets and shower valve use a single handles, and that means you always draw some cold water in when the valve is in the full-hot position. ...And the problem with that, when winterizing, is that your cold water side will back feed into your hot water tank if you do not have any check valves... and I don't because I removed them 2 year ago. (Pesky-beggars! ... these things broke and left me with cold showers for 3 days! So I removed them.)
Anyway, if you want to save anti-freeze, I recommend you start the winterizing process by purging all the cold water lines first... separately... and then repeat the cycle and purge all the hot lines.
PURGE ORDER FOR JUST THE COLD WATER LINE TO START WITH
* Outside shower cold water side only. This is to make sure you see "pink" and you know your syphon is working... as the anti-freeze level will drop.
* Kitchen cold water line only. (When you see pink shut the water off.)
* Shower cold water line only...
* Bathroom sink cold water only...
* Purge only the Shower cold water side...
* Purge the toilet water valve.
* Set the washer to the notch before the HOT water temperature setting... and start a wash cycle. This will mix mostly hot water with some cold. And when you see the tub spin slowly in about 1-minute, turn the wash cycle off. ...Then the washer to "Spin" on the dial and when all of the pink has been drained from the washer you are done. (I don't clean the tank like the video shows, but you can if you want.)
==> You just purged the cold and the hot water in your washer so now you can move on to purging the remaining hot water lines:
*** REPEAT THE PURGE ODER AS LISTED ABOVE ON THE HOT WATER LINE THIS TIME ***
* AND LET ENOUGH "PINK STUFF" OUT OF THE FAUCTS AND SHOWER TO FILL THE P-TRAP. This is very important, but your p-traps don't require that much of the pink stuff so don't waste it.
* Don't forget to purge your water filter if you have one... better still, remove the cartridge. (I really don't like these things... and this is a reminder that I need to remove this thing next season.)
* Don't forget to purge the hot water side of your outside shower!!! ...And since this is the last step in the winterizing process, you can turn the pump off and now open the outside shower hot and cold water valves... and leave them open!!!
* Once you are sure you have winterized your coach, I like to take the extra anti-freeze and pore in onto a flat container lid... and leave one on the tile floor in the front and kitchen and bath area. Why? The anti-freeze does not evaporate and if there are any bugs in your coach (ants, spiders, ???) they will find the anti-freeze and die.
* You can also use "damp-rid" desiccant to achieve better insect killing results and it does a good job preventing musty orders.
* OPEN ALL YOUR WATER VALVES! ...This is an added precaution that will allow any freezing moisture that may expand in the lines to NOT CRACK the pex water lines.
* I don't like to purge the refrigerator ice maker. Instead I will separate the cold water line and let all the fresh water run out. ...Then I reconnect it.
* NOW I FLUSH THE HOT WATER TANK
by releasing the pressure valve first and then the drain plug. Once all the water is out I will put the drain plug back in. ...Don't forget to close the pressure valve.
* AND FINALLY, I dump all the water in my fresh water tank.
Attachment: pdf for your records