Aqua-Hot System

[lthomas510]

We have a 2007 Monaco Signature Noble III and were having an issue with our Aqua-Hot system. We recently had the systems (ourselves/friend with boiler experience) clean the burner and replace the nozzle/filter as was done last August 2021. We noticed after putting in the boiler antifreeze a leak under the rv at the aqua-hot. No hot water of course and were not sure how to go about finding the leak or if anyone may have had any issue with the system in their Monaco!

Help would be appreciated.

[dbircky]

Is it water, Aqua Hot liquid or engine antifreeze? Does it start on diesel? These are fairly simple systems, but without knowing what is leaking, how much, and when it’s leaking any suggestion for a resolution is a WAG. Thanks.

[153stars]

They are big on splitting recovery tank hose also caps leaking. Normally I don't like lever lock caps but the lever is good at loosening them up and not trying to twist the neck off the tank. Oh yeah that can happen cap neck solder joint leak. There's a kit for that.

[Scepter40]

What I would do is put a small bucket under where it's leaking. Then you'll be able to determine whether it's the boiler fluid or engine coolant. The cabinets are caulked along the seams, so any leak inside the cabinet will come out of the bottom where the exhaust comes out. Failure points are the filler neck and overflow tubing (already mentioned above), and where the hoses connect to the tank. The PEX lines have adhesive (aircraft best I can tell) between the PEX and the heater hose with a clamp and then a clamp at the brass fitting that screws into the tank. Those heater hoses get heat cycled constantly and can get weak. The other failure can be a cracked tank (which is what I had). That can be fixed, but it's a pretty serious project. Worth it IMHO as a new system will run you $10K by the time you're done. I also ended up with a leak at the connection for the engine coolant loop and one at the heater hose connection for the PEX tubing after I pulled the whole system for the cracked tank. It's been interesting for sure.

After you gather a bit of whatever is leaking, that would determine next steps. You can pull back the rubber cover under the cap and if it's leaking there, you should see some sticky residue on the top of the tank. The overflow tank hose cracking should be fairly easily identified as well. After that, I'd pull the cover off the front and crank it up and see if you can see any leaking from the connections on the front and stick your finger in there and feel the insulation and see if it's wet. That'll at least point you in the right direction. I think I've also seen folks say that the circulation pumps can leak as well, so check that while you're in there.

Good luck!

[lthomas510]

The leak is antifreeze and the system board is showing we're locked out. We added new antifreeze and discovered its slowly running out below the system.
Scepter40, what does IMHO stand for and where on the tank is the overflow line?
Thanks!

[Scepter40]

Originally Posted by lthomas510

The leak is antifreeze and the system board is showing we're locked out. We added new antifreeze and discovered its slowly running out below the system.
Scepter40, what does IMHO stand for and where on the tank is the overflow line?
Thanks!

In my humble opinion....

You should have an overflow tank near the Aquahot unit itself. Mine is white and mounted on the aft wall just above the unit. It has a small (I think 1/4" plastic clear tube that runs from the bottom of the tank to a barbed fitting just under the radiator fill cap on the top if the unit. First picture is the new hose I put on and the second picture you can see the bottom of the tank.

To keep the differences in nomenclature straight, antifreeze is engine coolant and boiler fluid is what you put in your Aquahot. They are not the same. I use the Century boiler fluid in my Aquahot, but some folks switched to the Camco (I think) pink boiler fluid. There were several folks here years ago that had corrosion issues with the Century product, which is what I suspect caused the inside of my tank to rust and ultimately crack.

EDIT: If your unit will not start due to low fluid, it's also likely that your level sensor is broken. I found mine in pieces. You can bypass it in order to service the unit (and mine is still bypassed), but I don't recommend that route long term.

[lthomas510]

Thanks all for your input. Has anyone heard about or had replaced your Aqua-Hot with a refurbished system by Aqua-Hot as a less expensive fix?

LT 510

[Scepter40]

There are several companies that do it. prices I've seen just on the internet range in the ~$4K range for the rebuilt part. Not sure what that all includes but suffice to say it's not cheap. Labor is another unknown which I would expect to be a pretty hefty price tag.

[153stars]

Start with the basics. Read of a lot of good AH techs in posts that owners were happy with. The radiator neck to tank is the most common second tier ,not so easy repair. Kit available.... owners have devised their own before kit was available. Or remove and re-solder. Many threads on this repair.

[Cat568]

Most leaks out of the bottom, are much simpler. There are the cover screws, 4 or 5, that allow access to most leak sources visibly. The 2 covers are very easy to remove. If the tank is cracked, the manuals say the fluid will leak out of the AH exhaust pipe. There are hoses, after you take the covers off, that may be the source. I replaced mine with Home Depo pre made sink ones...and will keep close watch on their durability. Good luck. The covers are very easy to remove.

[Eric Koger]

Check one simple thing first before spending a lot of money and potentially unnecessary worry. There is about a gallon of expansion that occurs with the boiler fluid when heated. I found that the seal on my cap (where boiler fluid can be added) had deteriorated which would allow the boiler fluid to seep from under the cap and down around the neck, down to the bottom of the shroud and then out the bottom of the unit. If the boiler tank is full, at least a gallon or two can escape this way as the heater cycles. If you are fortunate enough to be a victim of this very common failure, you are in luck because the fix is easy, quick and cheap by simply replacing the cap. There is a reason they recommend replacing these caps often, however, it is a maintenance item that gets frequently overlooked. Good Luck!!

[gcederholm]

Originally Posted by lthomas510

We have a 2007 Monaco Signature Noble III and were having an issue with our Aqua-Hot system. We recently had the systems (ourselves/friend with boiler experience) clean the burner and replace the nozzle/filter as was done last August 2021. We noticed after putting in the boiler antifreeze a leak under the rv at the aqua-hot. No hot water of course and were not sure how to go about finding the leak or if anyone may have had any issue with the system in their Monaco!

Help would be appreciated.

Working from experience, I suggest you provide a little more info to help pinpoint guidance. Since you recently had the unit open to clean the burner chamber and change the nozzle, do you remember seeing any wet spots? Any chance that the maintenance work nicked a hose or jostled a fittting?

Do you know the model number of the unit? AHE-100-04S? Or maybe 600D? I’m not sure what Monaco was using in 2007 builds. There is a big difference in the overflow systems between 04S and 600D.

What boiler fluid are you using? Can you reliably determine if the leak is engine coolant or furnace boiler fluid? How quickly does fluid leak out? Drip or stream? How much can you catch in, say, an hour or overnight? Does it stop leaking after a time (like when it gets down to a certain level)? How much did you add back to top off after seeing the leak?

Can you tell where the leak is exiting the bay? There would be a big difference between “out the exhaust pipe” and “out the opening in the bay floor where the exhaust pipe is routed”.

Your system will have a control panel (~10 x 14 inches) mounted on a bay wall or ceiling close to the furnace. What lights are you seeing? If the “Low Fluid” light is on, does it go off when you top off the boiler?

[Mrbrain]

Originally Posted by gcederholm

Working from experience, I suggest you provide a little more info to help pinpoint guidance. Since you recently had the unit open to clean the burner chamber and change the nozzle, do you remember seeing any wet spots? Any chance that the maintenance work nicked a hose or jostled a fittting?

Do you know the model number of the unit? AHE-100-04S? Or maybe 600D? I’m not sure what Monaco was using in 2007 builds. There is a big difference in the overflow systems between 04S and 600D.

What boiler fluid are you using? Can you reliably determine if the leak is engine coolant or furnace boiler fluid? How quickly does fluid leak out? Drip or stream? How much can you catch in, say, an hour or overnight? Does it stop leaking after a time (like when it gets down to a certain level)? How much did you add back to top off after seeing the leak?

Can you tell where the leak is exiting the bay? There would be a big difference between “out the exhaust pipe” and “out the opening in the bay floor where the exhaust pipe is routed”.

Your system will have a control panel (~10 x 14 inches) mounted on a bay wall or ceiling close to the furnace. What lights are you seeing? If the “Low Fluid” light is on, does it go off when you top off the boiler?

I have some come out the exhaust lately..I eonder what that’s about?

[Mrbrain]

Comin* out exhaust means what ?
What could cause that?