I thought I might post all of the repairs, including my latest problem, that I have made on my Aqua Hot in the last 5 years in case others run into the same issues. Format will be symptoms and repairs. Although I like having the unit and the comfort it gives, it would seem that I have to keep a watchful eye on it. It reminds me of one of those old 2 cycle outboards that would run just long enough to get you out there but not always back :-)
Leaking cap- replaced. I went to a 7 lb cap to reduce stress on the system.
Leaking overflow tubing-replaced with silicone tubing.
Cracked burner flame sensor - replaced.
Burner would intermittently not fire up- Used 12V battery on the bench to fire the ignition coil 50 times. Failed to fire once, replaced.
Burner motor would not shut down after flame cut out, some up and down in RPM- replaced silver box controller and relocated to outside
Leaking stand pipe solder joint where cap receiver and steel pipe meet-replaced with silicone hose, clamps, and aluminum cap receiver.
Replaced button thermostats that fire the electric element preventatively, they had not failed (yet).
Leaking drain valve-replaced with 90 degree brass ball valve.
Leaking pex pipe coupling at a circulator pump valve- Cracked fitting, replaces with hose elbow and constant tension clamps.
Leaking cracked elbows on engine preheat loop- This is the latest fail that I am detailing below...
I noticed a small amount of red engine coolant on the left side piping between the circulator pump and the housing for the main tank. There is a union there and I tightened it just a bit thinking that was probably the source and all was well until this year. When I got home this fall and parked the MH I saw a wet area on the cement under the Aquahot around the drain valve outlet. I removed the covers and there was several cups worth of engine coolant in the base area under the burner. I sopped that up and wiped things down and noticed that the copper elbows that make the transition between the horizontal copper run and the vertical run up to the tank inlet points both had minute cracks in them right at the center of the bend. These elbows are formed with a very sharp bend and are not what I am used to using. The line without the pump in it had the worst crack. It is a classic stress fatigue fail caused by vibration. I spoke with Roger Berke and before I was able to tell him the source, he said "cracks at the elbows". So this is yet another weak point to keep an eye on. Each time I get a fail, my goal is to never have to travel the same route twice if there is a better way. My plan is to replace these copper elbows with silicone ones and constant tension clamps to allow some flex without forming stress cracks. The O.D. of 1/2 inch copper is 5/8" and silicone elbows are available for that size ID. I will post the fix photos when I am finished. The photo below is of the fail point on one side. For now I have the feed hoses pinched off and a foam ear plug tie wrapped to the copper elbow crack point to slow it down. I am down at least a quart of coolant. This is a fail that if it got bad enough, could give you trouble on the road.
Later Ed
