Greetings
At last, I have a substantive update for anybody interested regarding the resolution of the Hydro-Hot coolant leak problem on my 2006 Monterey which has been discussed on this forum since last winter when I first tried to resolve the problem. I had learned to live with this problem since last winter by minimizing the use of the diesel burner and opting for the electric heat source whenever possible because the coolant leakage rate seemed to be less with the electric element.
I just spent the last three days in Fort Lupton, Colorado at the Aqua-Hot manufacturing facility and had John Carrillo, an ex-Aqua-Hot employee who now runs his own Aqua-Hot mobile service operation, perform all of the work described below. John did an excellent job and I would recommend him highly when you need some work done on your Hydro-Hot or Aqua-Hot systems.
I have attached a series of digital images to help explain the root cause of my coolant leak problem.
The image titled "Hydro-Hot leak" shows the "Engine Preheat Out" connection on the backside of my unit and where, according to the Aqua-Hot tech in Arizona, the boiler coolant was leaking. I really didn't agree with his diagnosis because this circuit carries diesel engine coolant and not the boiler coolant which is what I had been leaking. Though it was clear that something had been "leaking" and collecting at this joint over the years, it just didn't make sense to me that this was the real source of my problem. Please note that this tubing is not centered where it exits through the cabinet wall...it is at least 1/2"-3/4" lower than it should be...more on this later.
When John finally got my unit removed and then disassembled, he discovered that there was a crack in a brass fitting on the return-to-tank circuit from the heating system...it was either overtightened when originally installed or just a "crappy" fitting. The images titled "Hydro-Hot repair (1)", "Hydro-Hot repair (4)" and "Hydro-Hot repair (5)" show this crack clearly. As seen in image "Hydro-Hot repair (2)", this fitting is located in the upper-right corner on the backside of the boiler tank and had clearly been leaking boiler coolant down the back of the tank and then accross the bottom. The "crap" attached to the boiler tank is actually the remains of the insulation which Aqua-Hot installs on all sides of these boilers when they build them in order to better retain heat.
As John continued with the disassembly process, it became obvious to me where the 5-10 gallons of boiler coolant which I had dumped into this system over the past 12-16 months had gone...it had been absorbed by all of the insulation material and though most/all of the water content of the coolant mixture had evaporated, the coolant content remained in the insulation and eventually caused it to deteriorate and when heated, stick to all sides of the boiler tank. Images "Hydro-Hot repair (3)" and "Hydro-Hot repair (6)" show some of this material stuck to various locations on the boiler tank.
When Aqua-Hot was still building the Hydro-Hot, they placed a solid piece of 1"-2" thick insulation underneath the bottom of each unit above the sheet metal floor...this insulation material was intended to insulate AND to support the boiler tank at the correct height inside the assembly. We discovered that the reason the "Engine Preheat Out" tubing (and actually all of the other tubes coming out of the cabinet walls) was not centered on the opening was because the leaking coolant had compromised the bearing capacity of the insulation underneath the boiler tank and it was no longer able to support the tank at its design height. The entire boiler tank had dropped down inside the assembly by about 1"-2".
So, John cleaned everything up, secured a new insulation kit from the factory folks, installed a new brass fitting at the problem site, replaced a few other parts which were very easy to replace when everything was already torn apart, put the unit back in my coach, filled it with all fresh boiler coolant and the job was finished. I've only used the system a few times in the past 24 hours but I'm confident that we found and repaired the root cause of my problem.
In summary, a few lessons I've learned from this experience;
1. Just because you may have a boiler coolant leak in your Aqua/Hydro-Hot system, don't let somebody automaticly tell you that the ONLY solution is to install a "new" system for $10,000.00!!! That's what folks were telling me but it made sense that there had to be a few other possible sources of coolant leaks which could be repaired for less than 10 big ones!!!
2. We all understand that it is very difficult to secure, train and retain good technicians to work on these systems. Most all of the techs are mobile and don't really have any shop environment in which to work. Most of what they do is the required annual services and occassionally, the complete replacement of a total system. I don't believe that very many of them would be able to completely disassemble, troubleshoot and reassemble one of these systems as was John Carrillo. It was time consuming and messy!!! He admitted that he would have rather just been removing my old system and installing a brand new system...it would have taken him less time and he would have made more money on the total job. But the bill to me would have been almost 10 times what the repair of my system ended up costing. And Good Sam is going to pick up part of the tab!!! So try and find an Aqua-Hot tech you can trust, who knows what he is doing and who is willing to think "outside the box" when it comes to repair options...many of them seem to jump straight to the purchase and installation of a brand new system despite the cost.
Sorry this was so long but this experience might be helpful for somebody else down the road and it might save somebody
Jim Gill
