While we were at a family camping trip last summer we discovered that our hot water (combination electric or propane) was leaking. In the leaking water was antifreeze. After a bit of investigating we determined the water was coming from somewhere on the underside of the hot water heater. We shut off the valve that is supposed to by pass the hot water heater but we still had a leak. For the balance of our camping trip we had to do without running water. This was very upsetting because we thought we had a bypass. I eventually determined that the check valve installed on the hot water intake was not working. This meant the bypass was failing.

Check valve that represents one half of the hot water bypass. This check valve failed.
After we returned I started telephoning the nearby RV repair places to find out about getting it fixed. I was horrified to hear the replacement was going to cost somewhere in the range of $1600. That is a lot of money and I decided before shelling it out, I would try to fix it myself.
The first step was to learn how to get at the tank. Stuff in RVs is packed in tight spaces and is very intimidating. Fortunately, I found this you tube video that described how to get the unit out. Thank you thank you

I watched it several time with my husband and we set out to remove the unit. We worked about 4 hours to get it out. A careful inspection of the unit and we found a small crack on the bottom. It was a tiny little hole looking to be about 3mm long and a half a mm wide. Yet it was enough of a leak to soak the floor in ten minutes. We are fortunate to have a neighbour who does a lot of welding and he kindly stopped by to check. His diagnosis was not good news. After poking the hole and banging and inspecting he said the tank was corroded on the inside. Probably the antifreeze in the tank due to the failed check valve had been a contributing factor. Welding it would be difficult since it was aluminum and it probably would either not work or the corroded tank would just start leaking somewhere else. He recommended replacing the tank.
I did a bunch of research on line and compared the price of the entire unit versus just the tank. As is often the case, the additional cost for the whole unit was not that much more than the cost of just the tank. The seven year old unit was having some issues with a constantly leaking pressure valve and the ignition system, while working, was also corroding. We decided to just pay the extra to get a new unit.
We immediately came up against the Canadian problem. The new unit ordered from the RV dealers in the area was going to $850 to $1200. Ordered directly from a Canadian dealer it would be $850. If I ordered it from the USA I would have to worry about taxes, duties and brokers fees. If I could order it from the US, and have it delivered to the US, I could get it for $452 Canadian. I am not sure why Canadians have to pay double plus for RV parts but we do. We opted to replace the unit after arriving in the USA. Due to our very cold fall weather, even if the water was working properly, we would have the trailer winterized with antifreeze and unusable anyway. I called the Laramie KOA we were planning on staying at for a full week while my husband attended a conference. They cheerfully agreed to accept the part there and hold it until we arrived. Meantime, I put the old unit back in without connecting the plumbing in order to fill the hole and make it proper as far as customs was concerned. I could legitimately tell them I had replaced a broken hot water heater unit with the same model while were in the USA. No duty, taxes or import issues that way. On arrival at Laramie our new hot water heater unit was waiting.
It took very little effort to remove the old one and set it beside the new one. Everything was a perfect match. I just pulled out the screws, cut the wiring and pulled the unit out.
The new unit looked so sharp and clean in it’s nice insulation box. It came with some extra corner braces and new hinge thingies for the door. It did not come with the door but that was okay because we had the old door.
I nearly made one potentially disastrous mistake. While I was proudly photographing the old and new tanks I heard a meow and turned around and spotted my cat checking out the new cat door. After chasing him back inside I propped the old outside door inside in order to keep the cat in.
First step was to match up the wires. I decided not to touch the old connectors and risk mixing up the previous wiring job. I just connected to old wires at the point I had cut them. That way was really easy because it was all colour coded. I used regular twist electrical connectors. The new wiring had to be carefully tucked back in on the top right but it went in. It took a bit of fiddling and wiggling. The trickiest part of the slide in process was to get the propane connection into the hole. I did that by tucking the propane connection to one side until the unit was almost in and then I went inside and there was just enough room to nudge it into the general vicinity of the hole. I had to go back out and fish around to find it and then carefully finish the process of nudging the unit in. It was too bad hubby dearest was off at his conference because I had to take multiple trips in and out in order to get the unit finally seated properly. I was assisted by Misty decided to jump on me and give me many puppy kisses each time I was working from the inside. This slowed me down some, but did cheer me up.
Once the unit was in place I was able to reconnect the propane and I used the nice shiny new corner braces with the old screws. The flange arrived sticking out and had to be bent back but it went easily. There was more than enough putty left to easily seal the new flanges.
And it is done! At least on the outside. Now that I no longer needed the door to prevent the cat from escaping I put it on over the nice new shiny unit.
Once the unit was in place outside, it was time to go to the back and connect the wiring and plumbing inside. I decided this time I was putting in a valve that manually opened and closed instead of a check valve. That way, if this ever happens again I can actually block off the hot water heater from the rest of the system and not be stuck with no water at all. Of course now that I have planned on it, it will never actually happen. I ended up making a couple of trips to the hardware store to get the correct new manual valve and some new connectors. Here you can see just before I started connecting the plumbing and electrical. I used lots of teflon tape on metal parts and I tightened as much as I could. It was a bear of a job because it was in such a small space but my vise grip sure came in handy.
And finally I needed to reconnect three wires from the trailer electrical supply from the unit. It’s now in and reconnected.
We are in an area where the forecast says it is still too cold to risk adding water to test the new unit. I expect to see lots of leaks at various points in the plumbing connections that will need more tightening. I am not that strong and it will have to be something hubby dearest does. I am assuming, of course, that the new unit is not defective. I suppose we could fill and test in a few weeks and discover something wrong and have to take it all out, send it back and start all over again. The company I dealt with is not one where I have ever had any issues so I am not expecting any. I am counting it done.
So we saved will over $1000 by doing this fix by ourselves and arranging a delivery of the new unit in the USA. It was not a hard fix. It was a multicuss job with lots of fussing but it was not hard. Even taking into account some six hours of work figuring things out and removing the unit the first time and four hours of putting the new unit back in, I figure my effort was worth about $100/hour. And that is a good thing.
Update Nov 22: We finally got far enough south to be able to use our water system again. As I expected I had two joints that needed tightening to stop leaks. One connecting elbow broke instead of tightening more. (ARRGG!!) I had to make another trip to the hardware store to replace that. The unit itself is now working perfectly!