[cwl1979]

Coach 435 was broken into years before i got it and the Aqua-Hot had an electrical fire. In an effort to not replace the system with a new or refurbished unit i decided to tackle this project myself. 
First thing to do was identify the problem.
   
Problem found
What caused this issue? Was it from the vandals? or something else entirely?
Guess i didn't get a picture of that but it turns out the 120 element had shorted internally and caught fire.
The next thing to do was see where it was leaking from. I was unable to tell where it was coming from while it was in the coach so..
   
time to remove it and leak check the tank
   
Once it was fully removed from the coach i removed all the covers by drilling out the rivets. I still couldn't make a definitive pinpoint on the leak. At this point i unsoldered all the copper pipes and removed the tank and coil. I took it over to the hose and flushed it out with water a couple times and discovered the 120 element was the source of the leak.
At this point i went to the local ACE and bought 2 caps for the 1/2 inch pipes and 2 1 inch plugs for the heater element holes. Slapped some pipe dope on everything and filled it with water in the yard.
   
I made sure the tank was sitting level and left it for a 24 hour leak down test. When i checked it the next afternoon the water level seemed the same with no visible wetness to speak of. The black mastic had been soaked in coolant from leaking out of the burned up 110 element. 
The tank and coil seemed to be fine so, This can be saved. I went through the website at https://www.heatmyrv.com and placed an order for parts.
While I'm waiting on the parts i figured id make a few improvements as well (like shutoff valves on ALL lines) and ordered new insulation for it and got it all cleaned up.    
Most of the parts should be here Friday so i can complete the rebuild. The new overflow tank and coolant wont be here for another week as they are ground freight only and I'm in Alaska. 

Parts i ordered from heatmyrv were aqua hot specific everything else i got from Amazon. I'm not spending 56 bucks for a fuse block, nor will i spend 39 bucks for a plastic overflow tank. Especially when i can get a polished aluminum one for 29.
A couple weird things i notice thou was the lack of shut-off valves for each loop so one doesn't have to drain the entire system to change an element. Another being why are they using horizontal flow valves on a vertical system? Using the right valves would help prevent the sticking people experience. I'm  still trying to figure out how i can adapt a household 240v thermostat to the system because 450 bucks for a 40 dollar thermostat is ridiculous. For now it will be a 110 and diesel operation. 

Ill continue this thread as the parts arrive and get added into the system.

[arcticdude]

Carl,

That’s good work! To add info for you, I had a 431 unit in my previous coach. I’ve never heard of any leaks other than the outer coil freezing and bursting a loop. Never heard of the tank leaking.

My unit was a 431/12. This was a 110 unit. I never ran into an issue running out of hot water under normal circumstances with just the single element. Even using it for heat and hot water was good until it got well into the 30’s for outside temperatures. Turning the diesel on kept us warm and lots of hot water during the cold.

As long as your coil is good, you should find you’re very functional with “just” 110 and 1 element.

On edit- I did not rivet the cover back on, I used appropriately sized sheet metal screws for easier removal in the future. Of course, I never had to take it off again.

[Jack Houpe]

If it were me I'd tap one of those caps with 1/4" tap and put a gauge on the tank and pump 15 psi in it and see if the seams leak that tank is only for the AH antifreeze so its not under high pressure like the coils around the tank speaking of which is the copper line for the hot water thats wrapped around the tank OK? If your going back original then there is one piece thats is pretty pricey its the thermal breaker that has two wired in and two wires out its amongst the other thermal switches.

We only use the AH for hot water and to preheat the engine so we only run the 120v element and have disconnected the 220v element. I forgot do you have roof AC units?

This dissection is very informative for me.

[cwl1979]

Jack
I still have the basement air conditioner, cant even test that as its to cold here already. I have pressure gauges to fill and bleed with i just didn't have a fill neck on the tank. Couldn't find a pressure test plug in town to fit. I have since re-soldered a fill neck back on and it should work.
   
 I was thinking about how i can modify the thermostat holder to accommodate a standard tank high limit thermostat. 40 bucks for a water heater rebuild kit vs 450 for a thermostat.  Further research has led me to know this isn't possible as the thermostat cant go high enough to account for engine heat. The workaround from Rudy will be just fine for me.

For now though i have fully insulated the case and placed all the stainless panels back on, might have cleaned them up with a gentle buff.

[Jack Houpe]

I'm with you on that an adjustable thermostat on the element itself would be a step up, how different is the bung for the thermostat? You going at a pace that makes me tired.

[folivier]

Carl since you have it all apart you might consider moving the tempering valve where it is more accessible. That's one of the service items that is difficult to access.

[bestgenman]

Carl, consider this …..
   

And this
   

And finally
   

Nice job so far!

[cwl1979]

Moving the mix valve would be a very smart idea. Also having shutoff valves and union fittings so it could be easily replaced / rebuilt. I'm going to have to head to the store and grab come more copper this morning. I realized after i got everything back together i forgot to install the hold backet so a bunch og it has to come apart again this morning to install it.
Yesterday all the shut off valves i ordered showed up so i reassembled the pluming on the Aqua-Hot. Before i did i needed to change some fittings so i could use the shutoff valves.    
I removed all the female fittings and installed male ends so i could attach the shut off valves

     
Assembly in progress

   

Here's how i ended the day

This morning i was going to get started on wiring everything back up.
   
Now I'm going to tear things apart again and move the mix valve and install the hold bracket i forgot.
For those wondering I'm a big fan of shut off valves. They save time and cleanup. I use them on anything i can, including... the tops of air bags. If one of the drive bags blows out just crawl under it and close that bag. Wait a few minutes and the remaining bags will lift you off your tires so you can continue to roll to a safer location or where it can be properly fixed. I crawled under my coach the other day looking to get a bellows number and realized all mine are plumbed with massive 1 inch line, a blown bag will drop things fast! That's going to be my next major project, replumb the air system with 3/8 line and push fittings.

[cwl1979]

Carl, consider this …..


And this


And finally


Nice job so far!

what's this?     inside the red circle, if i may ask?

[bestgenman]

The overflow tank (expansion tank or recovery tank) relies on vacuum to return the fluid to the AH.  I was always fighting leaks in the system from a bad cap or a loose hose from the high water temperature.  Moving the tank to an elevation above the top of the AH stopped all those problems.  It required the use of a tubular tank which 4” pvc fit the application.  You are looking at the sight tube on the end cap.

It has worked flawlessly for a couple of years so far.