Water heater only hot water for a few seconds then cold

[Splitshaft]

Originally Posted by Ryan9102

Let me preface this by saying I have read a lot of post of here about bypass valves in the wrong position but my bypass valves don't look anything like any other post please see the attached picture the trailer is new. After I have turned on the water heater and let the water get hot the water starts coming out hot but after a few seconds gets cold again. All of my shower valves are off not just on the head but at the knobs as well. I do have both switches inside the trailer and outside on the heater turned on and I know the tank is heating up. I have narrowed it down to this bypass valves situation. I have a feeling this should have 3 way valves installed inline to the water heater input and output connections however my valves are located before the water heater. Am I missing something? Or do I need to take th
it in and have them install the bypass differently?

There isn’t no hot water because the cold-water line is connected to the hot water line without a stop valve between. You aren’t never going to get any hot water like that!!! Not in a million years.

[ProfChuck]

What I can't see in the picture is if there is a valve under the cold water line going into the tank. If so, it may be the two way valve creating a bypass at the cold water inlet, in which case the water would be either directed into the tank for heating (cutting off the water to the hose going to the hot valve) or, in bypass position, it would direct water to the hot water lines directly and not to the tank. If they put an anti back flow valve in the outlet of the tank the water from the cold hose would not be able to enter the top of the tank, either, thus creating a "bypass" situation. Just can't tell what kind of valve is on the bottom under that blue pex pipe, if any. If there is one, it may need to be turned. If it is in the correct position, then it could be that the anti back flow valve is malfunctioning allowing cold water to mix with the hot. Looks like nothing is simple anymore.

[ProfChuck]

Originally Posted by Ryan9102

Let me preface this by saying I have read a lot of post of here about bypass valves in the wrong position but my bypass valves don't look anything like any other post please see the attached picture the trailer is new. After I have turned on the water heater and let the water get hot the water starts coming out hot but after a few seconds gets cold again. All of my shower valves are off not just on the head but at the knobs as well. I do have both switches inside the trailer and outside on the heater turned on and I know the tank is heating up. I have narrowed it down to this bypass valves situation. I have a feeling this should have 3 way valves installed inline to the water heater input and output connections however my valves are located before the water heater. Am I missing something? Or do I need to take th
it in and have them install the bypass differently?

Actually, I think I would take it in and have them show me how to get hot water and do the bypass with this arrangement. Maybe it will wake someone up. Interesting that everything is pex and then the one piece is a vinyl hose. Did they run out of the right connections?

[HerveVR]

If you have minimum skills, re-do it. Pex is easy to work with.

Awilson (post #13) gave the easiest way to do it right.

You will save $$$$ and lot of time. Bonus: Pride

[Iwritecode]

Originally Posted by FORKLIFMAN

I agree, the plumbing is in a bypass situation , shut off the bypass you will then go though the water heater. as Homer Simpson would say Dote!

No, the plumbing is in a "I have no idea what they were thinking when they installed it because that's never going to work" position.

If the OP turns either of those valves, he won't be getting any water at all.

[jeff64]

From what I see, the white(bypass)hose was incorrectly installed (after the valves). It should be before both valves and have a shutoff installed in the middle of it. No wonder you get lukewarm water

[onetonford]

IMHO The installer didn't use the correct valves and used what they had in stock. He should have used the three way valves for this to work correctly. But he was possibly a new worker and the valves looked the same so he used them instead how many units did he work on before they found it out???? and did they figure it out????