I wish I knew how to post pictures, but I don't, it sure would save a lot of dialog. We recently got a new (to us) trailer and in looking at the hot water heater we are completely confused. It has a red line labeled Hot and a blue line labeled Cold. There is another short line that runs from a junction between the hot water tank and the red line that is attached to a short blue line, there is no valve to turn, just a junction with the blue line running down to a junction with the other (cold) blue line. This particular junction has a valve that can be turned either in line with the blue line coming into the tank labeled cold or turned to align with the short blue line running down from the red (hot) line. We suspicion that this is a bypass, but how can that be? If we were to turn the valve to keep cold water from entering tank what would keep the water from backing up and back filling the hot water tank by running up the short blue line to the red line that has no turn off valve? I guess the short questions would be "doesn't a HWT bypass require two shut off valves? Or is there a check valve in the HWT that allow water to only flow out?

Bahcml wrote:I wish I knew how to post pictures, but I don't, it sure would save a lot of dialog.Upload your pics here, copy the url created, and paste it into your post.

Does it look something like this?If so that is a bypass. When the valve is aligned with the in coming cold the heater is operational. If aligned with the short blue line it is bypassed.

Bahcml wrote:I guess the short questions would be "doesn't a HWT bypass require two shut off valves? Or is there a check valve in the HWT that allow water to only flow out?Manufacturers install water heaters in differing ways, with one valve, two valves, or three valves ... in your case there would be a check valve to prevent water flow in the wrong direction.

The single valve is a two-way valve: it diverts the water either to the heater or the bypass connection, blocking the other. There is also with this system a check valve built into the hot water output of the water heater that prevents water from entering it via that connection when bypassed (or, I guess, at any other time as well).In short: there is indeed a check valve as you guessed.

Here's another one for the single valve. This is our camper.The valve position is in the bypass mode. Turn the level parallel to the tank and it will be flow into the tank.The thing that keep the water from back flowing into the tank when in bypass is the check valve on the hot (out) side between the tank and the bypass line:

Hot Water Tank Bypass | Good Sam Community

Bahcml
Explorer
Mar 24, 2018
Another question please, so now we need to clean out the HWT as the anode was pretty rank and we feel there is probably debris from the anode in the HWT. Since we now know we only have a check valve on the hot water side, and not a positive turn off in the bypass system, what would keep the gunk from entering the system if we fill the HWT with water and then try to vacuum it out (from the outside drain of course)? Is there a way to remove debris from the HWT that we are unaware of?
wa8yxm
Explorer III
Mar 22, 2018
There are three types of Bypass systems
1,2 and 3 valve
You have a one valve system

The valve, with the handle pointing toward the Water heater (or away from it) is "USE" and with the valve pointing toward the HOT is "Bypass" there is a check valve (Sorce of many problems) in the hot water outlet.

THe valve is what we call a 3-valve, why I don't know since it only sends water TWO different ways.

The two valve system replaces the check valve with a 2nd 3-way

The 3 valve system uses all quarter turn, one in the bypass line.

But you have the one valve system.
ktmrfs
Explorer II
Mar 22, 2018
and the units with one valve and a check valve can be an issue with hot water temperature. the check valve is nonlinear restriction and if you experience water temp change when you change the flow rate, like when another faucet turns on, or you turn the shower from full flow to reduced flow, your experiencing a check valve that exhibits the variable restriction. Solution is to pull it out and put in a two valve WH bypass. problem solved, water temp is constant over a wide range of water flow.

Dutchmen sport: this is what our 295RE had, and I had temp problems with various flow rates, went to the old style two handle bypass, problem solved.
Boon_Docker
Explorer III
Mar 22, 2018
Good to hear, enjoy your new home away from home !
Bahcml
Explorer
Mar 22, 2018
A BIG Thank You to all who responded! It look exactly like the picture posted by Boon Docker. Sure appreciate the information.
Boon_Docker
Explorer III
Mar 22, 2018
Hey Dutch, there is something not right about your setup. It does not have red and blue water lines. I would check into that if I were you.
DutchmenSport
Explorer
Mar 22, 2018
Here's another one for the single valve. This is our camper.

The valve position is in the bypass mode. Turn the level parallel to the tank and it will be flow into the tank.

The thing that keep the water from back flowing into the tank when in bypass is the check valve on the hot (out) side between the tank and the bypass line:
DrewE
Explorer II
Mar 22, 2018
The single valve is a two-way valve: it diverts the water either to the heater or the bypass connection, blocking the other. There is also with this system a check valve built into the hot water output of the water heater that prevents water from entering it via that connection when bypassed (or, I guess, at any other time as well).

In short: there is indeed a check valve as you guessed.
SoundGuy
Explorer
Mar 22, 2018
Bahcml wrote:
I guess the short questions would be "doesn't a HWT bypass require two shut off valves? Or is there a check valve in the HWT that allow water to only flow out?

Manufacturers install water heaters in differing ways, with one valve, two valves, or three valves ... in your case there would be a check valve to prevent water flow in the wrong direction.
Boon_Docker
Explorer III
Mar 22, 2018
Does it look something like this?

If so that is a bypass. When the valve is aligned with the in coming cold the heater is operational. If aligned with the short blue line it is bypassed.