Why must the water heater be bypassed?

[RedOrGreen]

My 2010 Jay Flight 26BH has valves to bypass the water heater, and the owner's manual instructs you to put the valves in the bypass position for winterizing the trailer by applying air pressure to the city water connection. So I am curious. Why is it necessary to bypass the water heater? Why not just flush the water out of the heater, too?

[RedOrGreen]

I may have found my own answer. The bypass does not seem to be there to necessarily prevent you from blowing the water out of the tank, but to perhaps prevent you from needing to put in 6 gallons (or whatever size the tank) of antifreeze to fill the heater tank in addition to the gallon or so to fill the lines.
Still, is there any reason to bypass the heater while blowing out the lines (and thus blow out the heater as well) and then switch in the bypass before putting in antifreeze?

[rvrev2]

Bypassing the water heaters does save a lot of antifreeze. I would guess that since the water heater has a drain valve that it doesn't need to be blown out. I even leave the water heater drain valve open all winter.

[kcconawa]

I always leave my H20 drain valve open all winter. When draining, I also open the releif valve to make it drain quicker. Fixing frozen plumbing in an RV is not fun! I learned that the hard way back in the 80's and will never again make that mistake. Pay the price for anti freeze, be paranoid making sure everything is drained, don't forget the P traps and outside shower.

[Gone Camping]

I agree it doesn't require as much antifreeze.

[cmcgilvery]

Several years ago, I was told by a serviceman at an rv dealership that you always bypass your water heater as the antifreeze will, if not thoroughly drained/flushed, gel up on you in the water heater. Is this not true?

[Jayco 23B]

I recently bought a new Jayco 23B and during the demo I was told to make sure to use the bypass to avoid getting antifreeze into the water heater and damaging it.

[One Country Boy]

I always drain in winter and leave the plug open all winter. I have never had to put anti-freeze in the lines here in Florida. I thought I might have made a mistake this past winter, we had an unusually long hard winter here in the panhandle.

If the mixture should gell in the water heater, I assume it could cause damage to the electric heating element or rod (for failure to recall what the rod is really called). I know of RV'ers that pull that rod every year to clean it. I'm told cleaning it regularly will extend the life. I believe the ac***ulation on the rod is due to osmosis. I personally have never cleaned ours. Any thoughts or experience with this would be appreciated. Thank you.

[RR Conductor]

I pretty much do the same as you Jim, close off the valves to the hot water heater (bypass) and let it drain on its own, that way no anti-freeze can get in it. Personally I screw the plug back in, finger tight, once the heater is empty to keep any critters from making it a home. I never put anti-freeze in the hot water heater as it's not needed, no water in there to freeze "if" you turn the valves to the bypass.

[McMonk]

I've always bypassed the HW tank for winter - drained the tank and left the plug off to allow for any possible expansion, then filled the pipes with antifreeze. As you guys have said, I've always understood that it's to save both a wack of antifreeze and to extend the life of the heater....this is our first trailer with an electric element in the HW tank & what's been said makes sense. Thankfully, after many long, dark minus 30 degree winters, never had to deal with any frost damage....