Originally Posted by dieselguy
Quote " Wrong on everything. You can't drain the hw heater unless you switch the valves unless you are trying to drain everything.
Winter bypass on your system is easy, just reverse each of the three valves. Then you can drain the hw heater tank. By switching the valves you can now use your water system without adding water to the hw heater tank."
I'm a bit slow here ... the guy wants to winterize his RV ... why are the previous post all wrong and why would you want to leave water in the system except for the HW heater?
I've most always winterized by compressed air as well. I drain the HW tank, leave the bypass valves alone, blow out the lines using faucets and stool lever, add a bit of pink stuff to each drain for the PTraps and call it a year.
I didn't feel like doing a lot of typing but guess I should have.
Many winterize by using air like yourself which is fine in some areas of the country. In areas where it gets below freezing for say a week at a time it is not the best method.
The best way, in my opinion and many others here, the safest way, is to switch the bypass valves. Then pull the anode or plug and drain the hw heater. Next add pink antifreeze by using an adding system and fresh water pump. When you do this properly, by opening each faucet till it flows pink, you will have added antifreeze thru all your water lines including your bypass pipes. At the same time antifreeze will go into your drains. Don't forget to do the outside shower. I am adding shutoff valves and going to drain these two lines so I won't have to be concerned about them.
In the spring add bleach and sanitize your fw tank. Then run your pump and flush out your water lines.
I suppose if all you are going to do is blow the water lines out it wasn't totally wrong but the only purpose of the bypass is not to just keep antifreeze out of the hw heater. They allow you to use your water if you wish without worrying about freezing the heaters tank, so you can properly drain the hw heater.
My concern with just using air is I have read, on here, where condensation built up in a low spot and then froze breaking a pipe. Maybe they were careless or didn't use a high enough air pressure? I don't know. I do know if all my lines have antifreeze in them I don't have to worry.