Big problem, then a very disappointing day.

We have an Aqua-Hot system in our coach.  It is a hydronic heating system that provides unlimited hot water, 3 zones of heating in the coach, keeps the basement warm, can preheat the engine on cold days, and can use 3 different sources of heat, a diesel burner, an electric element, or the engine's heat.  It is a fantastic system that is mostly bullet proof with just a little bit of maintenance.  But if one of a couple problems occur, you are in trouble.  You hope they don't but....

Back up a couple days, we came back to the motorhome after being away for awhile and Jan noticed what looked like a little leak back near the Aqua-Hot.  We checked it out and it looked like the fitting for the cold water inlet needed to be tightened a little.  So I tightened it up and we never gave it another thought.  Well, we noticed the next day the leak was still there?  So this time we did a little more investigation.  And what we found was not good.  The leaking liquid was antifreeze!  Now the way the Aqua-Hot works is it is basically a huge metal tank filled with 16 gallons of antifreeze, and it is the antifreeze that is actually heated by the heat sources, the antifreeze loops out to the various heating zones, and a heat exchanger or coil in the tank is where the domestic hot water comes from.  Now there are several "holes" in the tank, the two where the domestic hot water coil connects, the electric element, the antifreeze drain, the burner compartment itself, the thermostat, the high limit switch, well you get the idea.  These are mostly threaded fittings, no brainers if you will, if they leak you either tighten them up or pull them out, add a little teflon tape and you are good to go, but there are, as I said, some signs of catastrophic failure.  

We still had to find the leak which is more difficult than you would think.  You start at the top hoping to find the telltale sign of a wet trace down the side of the tank.  Now what makes it challenging is the entire unit is encased in a stainless steel case through which holes are made for the fittings and there is insulation between the tank and the cover, so it is very hard to find a leak, and we could not find it!  We kept working our way towards the bottom with no luck.  So we called our go to expert on Aqua-Hot, Rudy Legett, in Houston, and he gave us a couple places to look, inside the burner, and where the drain pipe comes out.  So we pulled out the burner and.........oh no, there is white residue in there, and a little trace of residue down the front of the burner case, then he told us to get a radiator pressure test kit at AutoZone which we did, pressurize the system, which will force the leak, and sure enough the leak got worse, still hard to find.  

This is the Aqua-Hot with the front cover pulled off.  That is the
burner out in the foreground out of our way.  The large circular opening
is the burner compartment and to the lower right of it you can
see two fittings the right one is the tank drain and the left one is the leaking fitting!

Finally we find what we think is the bad leak, around the fresh water cold inlet where it pierces the tank.  Talk it over with Rudy, call Aqua-Hot, and they agree that with the leak in the burner case, and the leak around the inlet, we are probably looking at a catastrophic failure!  

There should not be any white residue in here!!

Our unit is 8 years old and they don't make it anymore, but they have a newer unit that is essentially the same as ours that would go in, but, wow, it is really expen$$$$$ive!!  OMG!  Merry Christmas and Happy Birthday to me!

So we go into pow wow mode and start researching the issue, talking to Rudy, asking on Roger Berke's forum, the guru of hydronic heating, ask my good buddy John, another fix anything expert, and it looks worse and worse.  Maybe the one fitting could be brazed, but that doesn't solve the leak in the burner, could we epoxy, at least temporarily the fitting until we can replace the unit?  So that is our plan.  We'll epoxy it until we can replace it, that way we will have heat and hot water.

So today is the day.  First we have to empty the tank of antifreeze, all 16 gallons so it will be dry for the epoxy, which is kind of a feat all in itself, get the burner out of the way, then cut with a Dremel tool all the stainless steel cover we can to gain access to the bad fitting.  What a struggle, it is so tight in there, but we get it cut out, tip the motorhome to drain as much antifreeze as we can, then tip it the other way to get any remaining antifreeze away from the fitting, clean up the area as well as possible, then epoxy the crap out of it!  Wait and wait the hour it says, but we're nervous so we wait 2 full hours, and fill the tank back up.  Looks good so far, but we won't know until we fire it up and put heat and pressure to it.  And........it DOESN'T work!!  Still leaking badly.  Oh sh&**&^%t!  All day we work on it and nothing to show, not how our projects usually work out.  OK, calm down, plan B.

The failed epoxy repair:-(

Tomorrow we are going to go get a 6-10 gallon electric hot water heater, and hook it up in an adjoining bay.  That way we will have hot water until we can get a new replacement unit sent to us.  Jan and I, with some help from our good friends, Jack and Harvey, and who knows who else will pull out our present leaking unit, replace it with the new one, salvage and sell all the working, good parts on the old one and press on.  This coach is our house and we have no intention of trading it or getting out of our lifestyle, so this is a very unexpected expense, but one we will get through, and have a new dependable Aqua-Hot going forward.  I'm sure I will have some interesting stories of the install later.  And no, this is not normal or indicative of an Aqua-Hot, it is just bad luck!