Community Forums

Wrinklemeist · 07-11-2012, 09:42 AM

Ii have not found this topic in the Hydro Hot threads. A few days ago while having some plumbing work done on our coach, the tech, who is Hydro Hot certified, asked if i had ever changed out the fluid in the Hydro Hot and flushed the system. My Alpine is an '05 and I have had it for two years ago and haven't flushed it and don't know about previous owners. The tech checked the fluid in the hydro hot and it was nearly black. I told him to go ahead and flush the system and change out the plastic drain valve for brass and change the float sensor too. He drained the system then filled it about half way with distilled water, blew compressed air into the boiler to agitate the water, then drained that. It had a grrenish color and there were particles of green material which indicated corrosion of the copper lines due to the anti corrosion properties of the boiler fluid being exhausted. He then pumped distilled water through the whole system (both zones) until it ran clean. He used some 22 gallons of distilled water in the process. He told me that few people knew that this must be done and to check the fluid in the system on a regular basis--not just what is in the overflow tank. Has anyone else done this? I don't have the Hydro Hot manual so don't know if this is a part of reccommended maintenance. Any comments or input appreciated.

Perry White · 07-11-2012, 09:47 AM

No. But ask Roger Burke. He knows everything about them. How do you get Hydro-Hot certified? Can I ask what the cost was?

Wrinklemeist · 07-11-2012, 10:55 AM

From what I understand, you have to take a coiurse at the factory. The tech who did mine was more expensive than most at 100 bucks an hour. It took him aboiut 3 hours plus about 150 bucks for distilled water and boiler anti freeze. The float switch, drain valve was extra.

Wayne R · 07-11-2012, 11:47 AM

Sounds like snake oil.

Renipladlo · 07-13-2012, 06:53 PM

All - According to Aqua Hot you do not need to replace or flush the unit’s boiler antifreeze. But to be on the safe side, I would do a drain and refill with new boiler fluid every 5 - 7 years. If you have to drain it for any reason to replace an internal component, then you already have it out, put in the new stuff unless it is only a couple to four years old.

The boiler antifreeze is made by Camco, (http://www.camco.net/#) and can be purchased online from their site. Camping world can special order it, or you can call HH/AH direct and they will send you some for a price.

There are two types, they are: Boiler Antifreeze and Boiler Concentrate, personally I would use the boiler concentrate and read on the bottle the ratio of fluid to distilled water so you get the proper mix rate. Then someone with the correct type of hydrometer can test the mix level and adjust it accordingly more distilled water or more concentrate to get the proper mix ratio. The proper mix ratio ensures you are getting the maximum heat transfer rate from the fluid to the air handlers and the heat exchanger for your domestic hot water.

Wayne & Kathy, it's not snake oil, as you should be doing the same thing in the Main Engine Coolant for the coach, if not you can damage the engine.

FWIW - I am hydro hot/aqua hot trained from the factory, hense I speak truth.

Wayne R · 07-14-2012, 06:03 AM

Monty, I do change the antifreeze in my coach. I also check DCA level every 6 months and adjust it. I do this because it is a Cummins requirement and to prevent cavitations in a wet sleeve engine.

Flushing and changing the boiler fluid can’t hurt.

Renipladlo · 07-14-2012, 12:05 PM

You are correct. I will have to change the plastic pipe "drain valve assembly" on my HH unit once we get the coach back since it's been 5 years and i'm sure it brittle. So when I do that repair, I wil change the fluid at the same time. It turns very dark brown to almost black which HH assures me is normal.

Last August 2011, I had the coolant drained out and refilled with Fleetguard complete. Last April 1st, 2012 our coach was hit, and all or most of all that coolant went on to the ground because the car whacked the radiator stack. So, once repairs are complete, I have informed the repair place to refil it with Fleetguard Complete as well. It will need an oil change/fuel filter change, and cummins will have to do those since all my stuff is in Washington State, and the coach is in Phoenix area. I will have them check the DCA level at that time. I also need to have a transmission fluid sample pulled and sent off to update my original one since some of the tranny fluid was lost as well. Bringing the coach back alive I'm sure will show up other things not working, so I'm giving myself two weeks to make it ship shape so we can use it again.

Since cmmins will have it I will have them inspect the drive shaft U joints, and do a complete front/rear lube as well, again it's in their shop and might as well. I will ask to jump down in the pit and do a visual inspection of the repairs, but I'm going to climb under it once we get it back anyway to look and make sure everything is tight as it should be.

Roger Berke · 07-16-2012, 09:18 AM

The coolant in your Aqua-Hot does not need to be routinely changed. The system is a 'closed' system and does not pick up engine contaminates.

The Camco coolant will change color to look like Coke-Cola. This is normal and does not seem to hurt anything.

The PH of the coolant should be checked periodically. The pH of the Boiler antifreeze should remain between 7.5 and 9.3; if it tests lower than 7.5, galvanic corrosion may be accelerated.

The only reason to change coolant is PH out of normal range or something added to coolant that should not be there.

If your Aqua-Hot (model AHE-100-03, AHE-100-04, HHE-x00-08 or HHE-x00-09) still has any PEX parts they should be changed to brass. The plastic parts are very prone to failure.

- Roger Berke -
www.Forum.RVHYD.com

Renipladlo · 07-16-2012, 12:01 PM

Thank you Roger, you confirmed what I was told in School. But if I had to drain it out anyway, and it was over 5 years old. I would personally just refill with new stuff since some flushing occurs, and etc, etc, etc!!!

And yes, mine has pex drain assembly, once we get coach back, that is on my top 10 list to change out. Since it is summer, won't need heat, and can live without hot water for a day or so to do the work.

Keep up the great work you do helping members.