One thing:  when using this method, don't forget your toilet and any outside water outlets!

Originally posted by Jarhead Gotcha. So as long as I close the hot and cold to the heater I can leave the middle cne alone right ?

NO.. you have to use the middle one. It is part of the "bypass circuit"

At this time your top and bottom valves should be closed, AND, the middle valve should be open, allowing the anti freeze to flow around, or bypassing, the WH.

When you want to use the WH come spring, you have to open the top and bottom valves to allow water to flow into and through the WH.

If you do not close the center valve, some water will still bypass the WH.. Cold water. Unheated water. Unhappy to hit you in the shower water...

When you want to de-winterize, the idea is to thoroughly flush out all the antifreeze with fresh water.  To do that, you don't change the valve settings.  Once flushed, then you can go back and change the valves to allow water to flow through the water heater, including the middle valve.

Personally, I've never tried the blow it out method.  The antifreeze method is easy and the antifreeze solution is cheap, so I take the path of least resistance and have the confidence I've gotten enough of the water out and replaced with antifreeze to be sure nothing will freeze.  Many people really like the blow out method and have had good success with it.  I worry about not getting all the water out of things like toilet valves and don't to have to replace something like that b/c it had enough water left in it to crack it when the system froze.  But my worry is probably misplaced.  

The in and out valves stop water getting in the water heater.  The one in the middle let the water go from the cold side to the hot side (and all of your faucets) without going through the water heater.  If you don't close the in and out valves water will still get into the water heater, although some won't.

TT

Right, keep the HW bypassed until you flush your pink antifreeze out.  I did it that way the first year of ownership on a 177 back in 2011.  Was really frustrated about the nasty taste in the lines the following spring, took a few tries of lemon juice, white cider vinegar and baking soda sitting in the lines for about a week to get rid of the 'flavor' left from the antifreeze.  Many people don't drink from their FW tanks so this isn't an issue but for us who do, it was a big problem, especially for those of us who have great tasting well water.  I have a hard time drinking bottled water, to me it tastes weird.  However when in third world countries there are no other options except to get really, really sick.

Since that first year doing it the traditional way using antifreeze in the lines we have opted to use pressurized air to blow out all lines and then use a total of 16 oz. RV antifreeze for our 3 traps (2 sink, 1 shower) and a little for the toilet to keep the seal moist.  Live in northern Michigan and get some really cold weather, no issues or leaks in the last 7 years.