Aqua Hot

[Edward Buker]

The reason for this thread is to gather a little history regarding Aqua Hot leaks, basically where does the antifreeze go when we have to add to it. How often do you add antifreeze and how much. Hopefully we will build a little history of where to look for leaks and what is considered a normal amount of antifreeze replenishment. Hydro Hot folks can chime in, just comment on which system you are referring to.

I find myself adding antifreeze every month or two to my Aqua Hot, maybe a quart or two. For the life of me I do not know where it is going. My visible leak history has been the drain valve which I replaced. The tubing that goes between the cap receiver and the expansion tank which I replaced with silicone tubing. The cap itself which I have replaced twice. One of the compression elbows that feeds one of the zone plastic pipes had a cracked fitting which I replaced. The solder joint between the radiator cap receiver and the boiler pipe had a pinhole leak so I had to order the brass receiver and solder that on. (not fun doing this while the Aqua Hot is in place)

At this point I can find no leaks and on burner start up I do not get any telltale white smoke other than the normal condensation that clears quickly. So that is my list of leak points, repairs, and how much antifreeze I have to add over time.

Later Ed

[Karl Welhart]

I have a Hydro-Hot system that was replaced under warranty because of a faulty burn chamber within a year of purchase.  The system has worked perfectly ever since with an annual service of new nozzle, filter and cleaning of the burn tube.  I had a fresh water fitting leak in the back that was easy to fix.  Additionally, I have replaced the radiator cap twice and the expansion tank tubing once, just to avoid any problems.  Every three years I drain and replace the coolant.  My system runs in diesel mode all the time because of DW's long showers....  

Now for the important issue, I have never added coolant between complete drains and replacement.  We have been traveling in our MH 5-7 months a year for the last 11 years.  As far as my experience with leaks in other MH's with Hydro/Aqua-Hot systems, most have been from the old plastic drain valves and the expansion tank tubing.  Also, I have seen one situation of the radiator cap not tight.  The old style caps are particularly hard to get back on after they have been in place for several years.  One major problem with leaks on the coolant side of these systems is the nature of the antifreeze itself.  It evaporates without any residue.  Sometimes you will see a small amount of white powder near the leak area, but normally this occurs only in a high pressure/high temperature situation.

Ed, thanks for getting this tread started.  It is a very important issue for discussion.

Karl

[Steve Huber Co-Admin]

Ed,
In addition to your list, I had a cracked brass threaded sleeve where one of the line come through the top of the case to the check valve. Also has a leak on the rear of the unit at the mixer valve. Both of these resulted in antifreeze on the deck so were obvious.
I had the same issue as you. Had to keep adding fluid but no evidence of where it was going. In one case I found a pinhole leak in the hose from the expansion tank to the unit. The antifreeze was apparently dissipating due to the heat of the unit as it took a long time to find it. Replaced the "plastic: line with a rubber vacuum hose. The other leak was more fun. After adding small amounts for about a month. I finally saw a few drips on the deck. In checking, I found the wood "floor" under the unit to be saturated. The pressure cap was leaking but the fluid was running under the rubber "gasket" at the cap and inside the casing and down back of the unit. Volume as low enough that the wood absorbed it with no tell tale drips until it saturated.
Steve

[Sean Donohue]

I will be watching the post, same slow leakage issue. About every two months I am topping it off.  

[Orman Claxton]

Edward
What size is your radiator cap?, needs to be 13lbs.
Pull the burner, pull combustion chamber, look inside for sign of leak, check the insulation for signs of leakage.
Check inside around heat exchangers for leakage

[Edward Buker]

Orman,

Thanks for chiming in here, I know you have a lot of experience. I use a 7lb cap given I do not worry about boil over and keeping the pressure down I thought would be beneficial to preventing some type leaks. The 13lb cap, I am curious as to the reason behind that. I plan on pulling the burner and combustion chamber when I get home in the fall and cleaning and servicing the unit. I will check that whole area then.

Because the previous leaks have been quite visible, this one has been a bit of a surprise. I guess I was wondering if folks with Aqua Hot systems in use actually run these systems for months without the need of adding any antifreeze? Steve and Karl thanks for your insight. Sean we will see where this takes us...

Later Ed

[Stan Simpson]

I went to an Aqua Hot seminar in Gillette at the FMCA rally. It was very informative. These are some things we were told by:

Lloyd De Gerald
501-258-8426

He is from Little Rock, and is an actual tech. He does the work.

1. Aqua Hot and Hydro Hot are exactly the same thing. Same components, same mechanism, same process.

2. When a facility sends one of their techs to Aqua Hot school and he is certified, the entire garage is certified. So that is why Camping World can tell you they are Aqua Hot certified, even though the one guy who was certified quit two years ago.

3. The pressure/radiator cap must stay at 13 lbs..below that can ruin the entire system.

4. It is a very good idea to change the filter and the nozzle annually. He said he makes service calls and the owner tells him that he bought a new nozzle and gives it to him to use. The problem is not solved because the guy bought the new nozzle 9 months ago. He said its important to install them as soon as they are purchased. They can go bad in the bag due to moisture, unless its in a vacuum.

5. He said you can run the diesel burner by itself while driving, or both the diesel and electric at the same time. You will have hot water when you stop. The electric can be run by itself, but it takes about an hour to get hot water with just the electric element. He also emphasized that they diesel burner and the electric element are two totally different systems. One is not dependent on the other.

6. He said he leaves the electric on when he goes to bed and has hot water for coffee when he gets up.

7. He said there will always be a need to top off the boiler anti-freeze. The constant heating and cooling will naturally cause some evaporation. He said he would estimate about a quart per year, depending on usage.

8. He invited anyone in attendance to call him any time.

I hope I remembered everything correctly. Perhaps Orman will chime in here.

Stan

[Orman Claxton]

Sorry Ed
Would you get the model # for your unit
Thanks

[Edward Buker]

Orman,

I believe my unit is an Aqua Hot AHE 100-02S. It is a unit with no external panel and uses individual relays for zone controls.

Stan thanks for sharing that info.

Later Ed

[Orman Claxton]

Thought so,
Use the 13# Rad. Cap.

[Robert Mathis]

I guess that was what was wrong with my unit. I replaced the nozzle before I left the house, and the first time I tried to use it, it wouldn't burn right. I got another new nozzle and replaced it. Everything works fine now. I guess the first new nozzle must have been defective.

[Edward Buker]

Orman,

I'll go buy one on your recommendation but I am still puzzled what difference it will make. Do you think there is leakage around the cap or is this a pressure in the vessel issue with the burner or controls to work properly. The seal in the radiator cap is above the spring pressure regulator and I think this just means that the antifreeze mix heads to the expansion tank at 7lbs instead of 13lbs. Seems like that would be less stress on everything and therefor of benefit given all the places antifreeze seems find leak points,  under heat and pressure.

Any ideas on the reason behind this one?... I've always found 7 to be a lucky number and 13 to be an unlucky one and it would seem like I could use some luck in keeping these things leak free :-)

Later Ed

[Orman Claxton]

In the past we had a problem with the (HAGO)Brand Nozzle, something to do with tooling, I've been told.
We now use the (DANFOSS)Brand Nozzle
By the way, when I am performing an Annual service,I will not use a customers (SPARE). I have no idea if it is good or not.
I would not be able to warranty it.

[Orman Claxton]

Ed
Aqua-Hot Engineers recommends 13# radiator cap,Except for the older systems using the large cap

[Edward Buker]

Thanks Orman, they designed the system so I will head for the #13lb cap. Thanks for sharing the info.

Later Ed