Water heater bypass

Just to make sure there is no section of pipe holding water in between the bypass switch and the tank,I will drain the tank, blow air through it, then turn the bypass switch, and do it again.

Well, I would need 12 gallons as opposed to 2

I understand that at least one of the water-heater makers recommend against RV antifreeze in the tank

No advantage.
I drain the tank, blow out the lines, then remove the plug to insure there is no remaining water.
If you have a Suburban, it is good time to check and possibly replace the anode.
If Atwood, good time to inspect the plug to insure it's corners are not rounded off and needs replacing.

n7bsn wrote:
Well, I would need 12 gallons as opposed to 2

I understand that at least one of the water-heater makers recommend against RV antifreeze in the tank

OP isn't using anti-freeze just blowing lines out


I drain and blow lines only.

Because of water in bypass line I do open bypass valve while draining (leave cold and hot valves open) so that section doesn't have any trapped water.

Old-Biscuit wrote:

n7bsn wrote:
Well, I would need 12 gallons as opposed to 2

I understand that at least one of the water-heater makers recommend against RV antifreeze in the tank

OP isn't using anti-freeze just blowing lines out


I drain and blow lines only.

Because of water in bypass line I do open bypass valve while draining (leave cold and hot valves open) so that section doesn't have any trapped water.

Sounds like a good idea. I only use antifreeze in the traps and toilet so no danger of getting antifreeze in the hot water tank. Thanks for the suggestions.

enblethen wrote:
No advantage.
I drain the tank, blow out the lines, then remove the plug to insure there is no remaining water.
If you have a Suburban, it is good time to check and possibly replace the anode.
If Atwood, good time to inspect the plug to insure it's corners are not rounded off and needs replacing.

Good point about the plug. The nylon plug in mine came apart last year when I removed it. It is easy to overtighten them and I think that is what I did in the spring before. In any event they don't last forever so it is a good idea to check them closely when draining the tank.

I winterized my old unit yesterday by parking the RV on a slope, and draining the water tank & opening the low water points. I also bypassed the water heater and drained it. Once the water was drained, I closed the tank drain & poured a gallon of fresh new pink stuff in the tank.
I went inside, turned on the pump, and got the line to the bathroom sink flowing pink when the pump started sputtering like it was all gone.
What?
Just air out of the remaining fixtures.
What gives?
I moved the unit back on the level to pour in the second gallon (never had to do that before), when I realized what happened to the first gallon...
Yep.
When I turned on the pump, it pumped it all right out of the low water points! My work area is gravel, so none of it flowed out; I knew what had happened after I moved the rig back to the level location..

So.. lesson learned - close off the low water drain valves BEFORE starting the pump!

Been there, done that, got the T-shirt

My Father once poured 6 quarts of oil straight through the engine block of his car. Fortunately, he realized it before he started the engine to circulate the oil.

The bypass is for those who run pink through their lines. If you winterize dry, the bypass is irrelevant.

I open the crossfeed briefly while on compressed air to purge any possible water (shouldn't be any), but then I close it back up. This way, the back of the water heater is ready to go in the spring without any further action.

IF you don't bypass the water heater tank when using air, then you've got to pressurize the entire volume of the water heater tank along with all the plumbing lines. I suppose that's not a problem if you have a large air compressor, but I've got a tiny little one with a 1 gallon tank. It would take a long time for that little compressor to get everything including the water heater tank pressurized to 20+ psi or whatever air pressure you like to use for the blow out. So I always bypass the water heater tank, drain it, and leave the plug out for the winter.