water heater bypass

[recycled55]

Help this is one of those new to me questions. I recently acquired my first motorhome and want to know what a water heater bypass is. How do I find out if I already have one? Do I need one and if I do how does one of them function?
Most questions I find eventually but this one has evaded me so far.
thanks
recycled55

[Senior Chief]

You use a water heater bypass when winterizing your coach. To keep the water system from freezing you can pump a few gallons of RV (pink) antifreeze through your water lines, but the water heater itself holds 6 gallons or more. Pricey.

To avoid having to fill the WH with antifreeze, the bypass allows you to ...well, BYPASS the heater and just fill the relatively small volume of the water lines themselves. The WH is simply drained for the winter.

You'll have to actually look for the bypass, which is just a loop of waterpipe which goes from the inlet side to the outlet side of the WH,with a valve on either end where it goes into the WH (you have to be able to shut off the WH or shut off the bypass). Look in the exterior compartment where the burner is or in the access to the other side of the heater, probably located in the bathroom under or near the sink.

The bypass would have been something a previous owner installed, not a factory item.

Are you having issues?

[Senior Chief]

Oh, the question of whether you need one? Depends on where you live (do you need to winterize?) and whether you choose to winterize by using antifreeze or by blowing out the water with compressed air (they make a plumbing fitting with a Shrader valve on it for air).

If you just wanted to pay the $$ for the antifreeze to fill your WH, that works fine too.

[wa8yxm]

What is a water heater bypass? A method of shutting off water flow to the water heater so you can simply drain the water out in the winter (Fall) instead of filling it with six gallons of "pink stuff" (RV Antifreeze)

Do you have one: Yes.

Do you need it: NO.

What does it look like?

Find the cold water inlet pipe on the water heater, follow it back toward the water pump (you need not find the pump, if you are following away from the heater you are going the right way) you should see a valve, it will either be a "3-way" (3 pipes going to it) or a standard On/Off (only two pipes) if it's a 3-way that is it.

If it's an on off continue back toward the water pump and you should find a "T" fitting, the "T"ed line will have a 2nd valve, now look at the hot water pipe, if there is a valve there you have the best (3-valve) system, if not a 2-Valve system.

How to operate

1 valve: Switch to the "Bypass' position, (usually this means the handle points in some way toward the third pipe, which by the way runs up to a "T" fitting in the hot water line)

2: Valve, operate BOTH valves, closing the one leading to the heater and opening the "Bypass" line.

3: Valve operate all 3, closing the two valves that go to the heater and openign the center (Bypass) valve

NOTE: in the one and 2 valve systems there is a check valve on the water heater outlet, this valve causes much grief, which is why the 3 valve is best.

Why you don't need it:

There are 3 ways to winterize

1: Wet method; Which does require a water heater bypass

2: Dry method. In the dry method you need not bypass the heater since you are going to fill it full of air. You open all low point drains, all valves and remove the drain plug from the heater.. When heater is dry, replace plug (you will do this at least 2 or 3 times) blow air at around 50PSI into city water inlet. (Drain main water tank and water pump lines too)

Pause, blow, pause, blow, pause blow, say around 10 times, pauseing for at least a few mintues each time, till you get no more water out of the lines

Now use pink stuff (A small fraction of what it would take to fill all the lines) in drains and toilets to prevent the traps from freezing.

Method 3: Drive SOUTH till you don't have to worry about freezing (One I use)

[recycled55]

Thanks everyone who responded. I am out of town and away from my MH for a few days but I think I can make sense of it now.
wa8yxm, Your explanation really cleared it up. thanks again.
recycled55

[frankdamp]

There's just one valve on my rig. I guess you'd call it a wate r heater shutoff. I drained the water out of the WH by removing the anode rod, then closed the valve and blew out all the lines with air. Since no air or water went into the WH, I guess there's a check valve someplace.

We don't get very cold winters in Anacortes - lows not usually much below about 25F and it's very rare to get days when the high doesn't get above 35.

["007"]

Here is some pictures of what the by-pass valves will look like.
As been mentioned will bypass the HW tank.
Other pictures

Winterizing

Welcome to irv2.

[recycled55]

I finally got to searching for my heater plumbing and found a valve (note just one valve ) directly behind the water heater. It was placed by a previous owner.
It was closed so no water went to the heater. I opened it to check its operation and now know how to winterize it.
I had to remove a panel under the bed to access it. Quite a task finding it.
recycled55

[lostagain]

There are three types of bypass systems. Check this link.

RV Water Heater Bypass Systems