Adding fluid to Agua Hot

[James Sagerser]

Lately, I’ve noticed a recent small fluid leak under to coach which seems like Hydro Hot fluid and sure enough, when I tried to turn on the Aqua Hot, it wouldn’t start nor would the electric burner.  I check the panel and the red “emergency cutoff” switch light was illuminated plus the over flow tank was empty.  Guessing the system was shut off due to a low coolant level, I tried to remove the radiator cap.  I tried to press it down to turn it but it wouldn’t budge.  It’s a given that I need to find the leak and address that issue but in the mean time, since I’m on a trip, I would like to add more fluid to get it working until I get back home to repair it properly.  Question #1:  Any hints on how to free up the radiator cap so I can push it down to turn it?  Should I tap it with a piece of wood?  Question #2:  Can the main tank be filled via the overflow tank?  Is the cap a one-way system so it will fill from the overflow tank with out the Aqua Hot cooling to draw it back into the main tank?  Thanks in advance.  Jim

[Edward Buker]

James,

The cap, like other radiator caps, if it is fully tightened has to be pushed down at some point to work by the metal retainer tabs, usually after it is fully loosened, so it should just turn. I usually push down while loosening a cap out of habit but that is usually only needed where the tabs are involved. Try using a wand on some WD40 and flooding the underside of the cap several times, may not help but will not hurt. The cap probably has not been worked in a long time and the rubber has adhered to the brass receiver surface. You have to break the bond and may need a set of channel locks or a strap wrench on the cap, being as gentle as you can breaking it loose. If it seems to require much effort, spray some more and wait. You do not want to damage or break the joint of the brass receiver below. I would try and have a new cap available, some of the old rubber seal surface will likely remain stuck. Some plumbers clear silicone grease/lube, available at HD or Lowe's on the new cap gasket will prevent this issue and aid with the sealing. Good luck, may the force be with you...

Later Ed

[Dick Simonis]

Awhile back I also had a leak that turned out to be a crack in the overflow hose.  Naturally the solution was a new hose...easy enough but after replacing it I refilled the surge tank to the full mark which was a big mistake.  as it heated up it began to overflow until I removed almost a gallon of antifreeze.  Bit of a brain fade on my part.

Moral of the story, when you are ready to start up again only fill the tank about 1/4 than top off when hot.

[LaMonte Monnell]

I had to slowly work my cap loose with a long screwdriver and pushed down on the cap while I slowly turned the screwdriver.

[Steve Huber Co-Admin]

James,
Check around the radiator cap for antifreeze before and after removing it. An old gasket can leak and the leaked fluid will run inside the  outer Aqua Hot housing so it is not obvious on the outer surface of the housing.
Steve

[James Sagerser]

Here's a nifty little trick; I filled the overflow bottle about half full, put the overflow cap back on and blew through the over flow tube to pressurize the overflow bottle.  The fluid slowly went back into the boiler tank.  The red light went out and am back in business.  Nice temporary fix without removing the boiler tank cap. Will find the leak when I get home.  This was also a good way to test the tube running from the overflow tank to the radiator cap as it was under pressure.  Wasn't leaking there.  Will check the boiler cap when it hot.  Also noticed the fluid leaking close to the engine so think it might be a connection there.  One note; when plowing in the overflow tube, you must put your thumb over the pinhole in the cab to seal it well.   Thanks everyone.  Jim

[David T. Richelderfer]

When our AquaHot developed its leak it started as a very slow drip and increased dramatically over a several week period.  Our leak was showing coming right out of the bottom of the stainless box that houses the AquaHot.  Upon looking inside the stainless box it appeared the fluid was coming out from the insulation around the AquaHot frame.  I feared the worst.  When I got Mike Flowerday to repair the leak two years ago in La Pine, Oregon the leak due to a deteriorated rubber O-ring between the electric, screw-in element and the AquaHot frame.  He put in a new element and new O-ring which stopped the leak.

[Stan Simpson]

James,

I will try your method if it's ever necessary. What a great solution. I also have a hard time getting the cap off. What causes my problem, even after I push down and get the tabs to go under the rim of the cap, the first turn runs the tabs right in to a hose clamp. It takes me a long time to get that cap off.

[jeffprupis]

Had Aqua Hot check my system at FMCA Rally. They said the number 1 issue with non-functioning HYDRO-HOT system is faulty radiator caps. Try replacing yours. The new Aqua Hot systems don't even have radiator caps.