What good is the HW tank bypass valve on the Anderson docking station?

[07 ThunderRoad]

After repairing a major flood in the basement of our coach, I looked at the plumbing of the Anderson docking center. The hot water bypass valve, on the right, bypassed the fresh water around the hot water tank. This causes the hot water tank piping to remain isolated from the system when adding antifreeze. What good is this valve? Is it possible our coach is piped wrong?

[schrederman]

I will drain my system as good as I can first, including removing the anode rod and letting the HW tank drain. That will usually drain those lines. Not saying it will for your rig, since I have no clue how it's plumbed.

[Ford Idaho]

How big is your heater 6-10 gallons?

At about 3 bucks a gallon do you really want to fill the tank?

[KyDan]

He's NOT filling his HW tank.

I drain my water heater and then blow the system out with air.
This removes the water from the bypass area.
Then I close the tank valves and open the bypass and pump the
system full of the pink stuff.

Works for me.
YMMV

[07 ThunderRoad]

The HW tank has the bypass valve on the back of it. This is what I don't understand. The bypass valves are on the HW tank for draining and adding antifreeze. Why do I need the Anderson HW bypass. The only use I see is it takes the HW tank out of the pressurized plumbing system when the coach is in use.

[Ford Idaho]

Originally Posted by KyDan

He's NOT filling his HW tank.

I drain my water heater and then blow the system out with air.
This removes the water from the bypass area.
Then I close the tank valves and open the bypass and pump the
system full of the pink stuff.

Works for me.
YMMV

I know!

[Tiggerdad]

The bypass valve is designed to be open with the inlet and outlet valves to be closed to keep the tank from receiving antifreeze during weatherization. HW heaters with antifreeze in them can be harder to flush to get the taste out. Heater still must be drained for the winter if bypassed. I would drain for winter whether antifreeze is added or not.

One does not have to bypass the tank if you so desire.

[Acableguy06]

This valve is so during winterizing you can bypass the tank and not be filling it with antifreeze. I drain my tank, then pressurize the water system with air and blow out all the lines, then switch my hot water bypass to shut off the hot water tank and bypass it. Then pump the antifreeze thru the system, less the hot water tank.

[jkklops]

saves a ton of the pink stuff if you pull out anode rod tank will be empty no reason to put pink stuff in it

[mikegp1]

If I'm reading your post correctly you have 2 separate bypass valves for your water heater. If it was me I would leave the one at the panel normal and use the one right on the tank. That way all your lines are covered.

[rockfordroo]

So, your REAL question, which hasn't yet been answered is:

Why are there TWO hot water bypass valves on your coach, one at the HW heater and one at the docking center???

I know that I don't know the answer.

[garbonz]

pictures might help. I have one valve that does it all, albeit with a ridiculous amout of piping. LOL

[07 ThunderRoad]

Originally Posted by mikegp1

If I'm reading your post correctly you have 2 separate bypass valves for your water heater. If it was me I would leave the one at the panel normal and use the one right on the tank. That way all your lines are covered.

BINGO!! Why did Prime Time Install both bypasses? The reason I am asking is the connection between the Anderson H.W. bypass and the water source valve on the left exploded and flooded the coach.
Keep an eye on that crappy tee with the plastic nuts or you may have a flood too. That tee is what keeps the valves from rotating when you turn the handle.

[BarryD0706]

Originally Posted by 07 ThunderRoad

After repairing a major flood in the basement of our coach, I looked at the plumbing of the Anderson docking center. The hot water bypass valve, on the right, bypassed the fresh water around the hot water tank. This causes the hot water tank piping to remain isolated from the system when adding antifreeze. What good is this valve? Is it possible our coach is piped wrong?

Hi Thunder. Another 2013 Sanibel owner here. I just looked at some pics and video I had made of that area of my RV. I think you may be mistaking the Atwood mixing valve for part of a bypass system. (That's the thing that gives your 10-gallon tank a rating of 16 gallons in case you didn't know.) I see a yellow shutoff valve at the bottom of the tank, but I don't see anything that would shut off the top of the tank (hot side) from the rest of the plumbing, and I don't see anything that would bypass the cold water into the hot water lines. All of those functions are done by the brass valve in the control center.

[07 ThunderRoad]

Originally Posted by BarryD0706

Hi Thunder. Another 2013 Sanibel owner here. I just looked at some pics and video I had made of that area of my RV. I think you may be mistaking the Atwood mixing valve for part of a bypass system. (That's the thing that gives your 10-gallon tank a rating of 16 gallons in case you didn't know.) I see a yellow shutoff valve at the bottom of the tank, but I don't see anything that would shut off the top of the tank (hot side) from the rest of the plumbing, and I don't see anything that would bypass the cold water into the hot water lines. All of those functions are done by the brass valve in the control center.

Hi Barry. You may want to check out page 39 ( as printed on the bottom of the page ) of this Atwood H.W. heater parts list. http://www.atwoodmobile.com/manuals/...rPartsList.pdf The ball valve is for winterizing the hoses and bypass of the tank. The mixing valve has a back flow check valve built into it. This check only allows hot water to exit the tank, at the top, and mix with the cold from the bypass hose. The mixing valve will not allow cold water to flow back into the top of the tank. This is my understanding of how the tank valves work. I guess I will have to test the valves my self and report back. Thanks for your input.

[BarryD0706]

I see what you mean. I wouldn't expect the hot line to get cold water thru the mixing valve however (since the cold temp should be telling it not to mix any cold into the flow).

But back to your question: The valves on the back of the WH tank are supplied by Atwood. I personally am very happy that I don't have to get into that panel to winterize. It's way easier to do it in the Control Center IMO, so I thank PrimeTime for adding that convenience.

[07 ThunderRoad]

When I had the great flood, I checked the hot water bypass valve piping and the 2 positions. In the normal position, the water supply "in" is connected to the cold water connection on the tank and the tanks' hot water out is connected to the hot water lines to the fixtures. In the bypass position, the supply line "in" is connected to the hot water lines to the fixture and the tanks' hot water out is connected to the tanks' cold water connection. If you winterize the system with the Anderson valve in the bypass position, the lines to the hot water tank will not be protected because they are isolated in their own loop.

[rockfordroo]

The ball valve is for winterizing the hoses and bypass of the tank. The mixing valve has a back flow check valve built into it. This check only allows hot water to exit the tank, at the top, and mix with the cold from the bypass hose.

Now I'm confused. Why in the world is there a mixing valve on the discharge of the HW heater? Usually mixing valves are only used to mix some hot water with the cold water on the line to a toilet so it doesn't sweat in humid weather. Why would you want to connect your hot and cold with a mixing valve at the HW line of the heater???

[BarryD0706]

Originally Posted by rockfordroo

Now I'm confused. Why in the world is there a mixing valve on the discharge of the HW heater? Usually mixing valves are only used to mix some hot water with the cold water on the line to a toilet so it doesn't sweat in humid weather. Why would you want to connect your hot and cold with a mixing valve at the HW line of the heater???

It's an Atwood feature. You super-heat the water in the tank. Then you mix it with cold water to get the temp down to "normal hot" as it comes out of the tank. This means that you're drawing way less water out of the tank, so it appears to have more capacity. An actual 10-gallon tank on an Atwood delivers 16 gallons of hot water. Very nice.

[07 ThunderRoad]

What he said ^^^