Water heater not heating water

[Coast6wa]

So we have a few problems, we have a 2011 25FB flying cloud. Our water heater is not heating the water. It was going on and seemed to be heating the water but as mentioned in other posts the water would be warm for a few seconds then cold, then warm then just cold. We are currently using the water pump because apparently a valve between the tanks is faulty and if we leave the city water hooked up and on, we get water pouring out of the fresh water tank inlet. We had taken the airstream to get it looked over before using it and they said it was fine! Not so! This water problem existed last time we used it but apparently they missed it. I don't know if the two issues are related. We tried to find the bypass valve thinking this could be causing the issue with the water heater, can't see anything that could be either the bypass valve anywhere. WE located the back of the water heater, and there is nothing like the mixer valve mentioned in other posts. We can see all sides of the heater now and all there is coming in and out are red pvc pipe and white pvc pipe. There are 3 valves which are all inline and a flush valve. Help!

[Lumatic]

A photo of the back of your hot water heater would help. When you say you have 3 inline valves it sounds like you do have a bypass valve.

[rmkrum]

This may be a bit hard to explain, but here goes. This assumes all three of the valves you found are on the back of the water heater.

The bypass system on older trailers used three valves. One on the supply side of the water heater, usually blue or white tubing, and one on the output side of the water heater, usually red tubing. There is a third valve that is between the red pipe and the blue or white pipe. That is the bypass valve.

To use the hot water, the bypass valve should be shut (crosswise to the pipe) and the other two valves should be open, lined up with the pipe. If you leave the bypass valve open, and try to use hot water, you will get the result you describe, because cold water will go around the water heater, and the hot water will happily stay in the tank.

To winterize, you open the bypass valve and close the other two valves. This lets you drain water out of the water heater by removing the plug outside under the water heater cover. This valve configuration lets you run RV antifreeze into your water system without trying to fill the water heater tank (6 gallons or so) with expensive antifreeze.

[A W Warn]

Originally Posted by Coast6wa

<<snip>> water would be warm for a few seconds then cold, then warm then just cold. <<snip>> There are 3 valves which are all inline and a flush valve. Help!

Sounds like the by pass valve is open, but it should be closed during use. (the valve in the middle) Turn it clockwise till it stops.

The cold in and the hot out should be open. Turn them counterclockwise until they stop.

This video shows them, and near the end of the video actually explains the function (skip the first half)

https://www.youtube.com/watch?v=z61bWSAu16g

[rmkrum]

In the above video still picture, the "bypass valve" we're talking about is the one with both red and white pipes connected to it. That's the one that should be shut (handle crosswise to pipe) to use the hot water.

This video still shows the water heater set to bypass for winterizing the trailer.

[Al and Missy]

OP's problem is exactly the one I had and chased for a week before discovering the bypass valve open. My trailer had a valve to shut off the outside spigot which I had confused with the bypass valve. My bypass valve was barely reachable on the side of the heater up against the cabinet wall.

Al

[daleyocum]

If you have a 25 twin you get to that bypass valve from the top under one of the twin beds. In mine there’s a hole above it in the plywood.

[Coast6wa]

Everyone- thanks so much for your help! We did locate the bypass with your clear instructions and we now have hot water! Thanks to rmkrum for the video! It was perfect for those of us trying to understand to some degree, the workings of our airstream. Your help is greatly appreciated.

[rmkrum]

Please thank contributor A W Warn for the video. I just wrote a few comments on the still picture from the video. Wasn’t where I could upload anything...

The funny bit is that I no longer have a standard water heater. Went tankless years ago, and all I do with it is blow it dry with air. No more bypass valves to mess with in tight spaces, and DW loves the endless hot showers. Priceless.

[Coast6wa]

A tankless is a great idea- didn’t even know that was an option! We will def check that out! Now, we will deal with the water pump issue. Let’s hope that’s it for now, we will be living in “Ingrid” for awhile while building a house.

[rmkrum]

We did a PrecisionTemp 500 series that fit into the same opening as the 6 gallon Atwood. Had to trim the top of the opening about 3/8 of an inch to get it in. Needed a ‘foot’ to support the bottom edge of the enclosure at the back corner to keep skin from flexing. Power and propane the same. Repositioned the original propane line about 2 inches to mate with the new heater’s fittings.

Nice thing is we got 40 pounds of water weight off the streetside of the AS in front of the axles and it is silent if you leave it on at night. The Atwood kept heating water in the middle of the night, and it was in the closet near the head of our bed. The PrecisionTemp only makes noise when you are using hot water.
We also ordered it with an unpainted door that matches the Airstream better. The Atwood had a painted white door. Did have to trim back the lower body molding an inch on each side of the door, as it was a touch wider than the old one.
Took a day to do it, but worth the money and effort.

[A W Warn]

Originally Posted by rmkrum

We did a PrecisionTemp 500 series that fit into the same opening as the 6 gallon Atwood. Had to trim the top of the opening about 3/8 of an inch to get it in. Needed a ‘foot’ to support the bottom edge of the enclosure at the back corner to keep skin from flexing. Power and propane the same. Repositioned the original propane line about 2 inches to mate with the new heater’s fittings.

Nice thing is we got 40 pounds of water weight off the streetside of the AS in front of the axles and it is silent if you leave it on at night. The Atwood kept heating water in the middle of the night, and it was in the closet near the head of our bed. The PrecisionTemp only makes noise when you are using hot water.
We also ordered it with an unpainted door that matches the Airstream better. The Atwood had a painted white door. Did have to trim back the lower body molding an inch on each side of the door, as it was a touch wider than the old one.
Took a day to do it, but worth the money and effort.

Have you traveled in freezing weather towing, with no water source attached? I'm wondering how the small amount of water inside the WH is kept from freezing. Does the WH cycle on/off? Or does it have to be drained each time?
(I have on-demand/tankless natural gas WH at home and love it)

[rmkrum]

The PrecisionTemp 500 series has a freeze protection system. It has heaters for the electronics and as long as water is in it, and 12 volt power is turned on, it will prevent it from getting too cold. We have used this setup in cold weather many times. Just leave it switched on when it might get below freezing and it takes care of itself. I’ve heard it fire up briefly at night when it was under 26 degrees outside while moochdocking in northern Alabama one winter. We just disconnected shore water hose, and ran on tank water when it got real cold. In storage, I thoroughly blow out the water system with compressed air and put some RV antifreeze in the lines as an extra precaution.