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Hydrahot (aquahot) leak.

Yahoo Message Number: 71615
On 6/7/2011 11:14 PM, david roberts wrote:
Quote
Hi Ken, Read your note about the leak on your hydrohot system. Not > sure what rig you have.

We have had a leak in our aquahot system from day one. Unfortunately > because we didn't use the coach much in the first year of ownership > (new in 2006) we didn't realize we had a real problem until using the > coach in colder weather when the heating was required. What boiler > fluid we lost was intially diagnosed as simply getting air our of the > system.

By the time we relized we had a more serious issue the one year > warranty was up. Did the simple fixes like replacing the plastic > valve and tightening up every connection in sight but still we have a > leak.

I am now keeping the reservoir topped up daily whenever we use the > heat and that seems to do the trick. The cost to replace the system > is outrageous. What bugs me is that the leak could be a simple > connection problem inside the unit but as you know the manufacturer > has provided no access panel to view the interior.
For the time being we are just living with the situation.
Safe travels.
David 2006 Allure
Thanks for your answer, David. Every time I add fluid to the Hydro-Hot, it seems to leak more!:-( At some point, I may engage a genius to disassemble the whole thing to see if I can get past the "outrageous" Hydro (Aqua) Hot system. It is hard for me to believe that the tank itself has so little integrity that it would leak so profusely.

Ken

2004 Allure #31035

Re: Hydrahot (aquahot) leak.

Reply #1 –
Yahoo Message Number: 71622
Ken,

I had a lighting and smoking problem with my Aqua Hot and used John Carrillo from Longmont Co for repairs. He is an ex employee of Hydro Hot and seemed to be very expert and has access to parts. He does not charge shop prices. He travels to a few rallies.

You could discuss this with him and see if he could give you an idea in what's involved in the repair.

John Shankland

John Carrillo
Hydronic Heating Systems Specialist 1316 Red Mountain Dr.
Longmont, CO. 80504
Tel: 970-518-3085
Email: jcarrillo@... www.aqua-hotservices.com

Re: Hydrahot (aquahot) leak.

Reply #2 –
Yahoo Message Number: 71628
Ken,

Count me in as one of the lucky folks to be in the Camco Boiler 100 club. Perhaps my experiences and observations might be of help to you and a few others. As for fluid, I was going through a quart+ every month. HydroHot themselves aren't really helpful about providing information. I think the HydroHot unit is one of those great ideas that falls a little short on proper design. As in being "almost" right. The last bit of proper design thus falls on the wallets of the end user.
On my unit the low tank level switch was a cheap plastic part. It eventually succumbed to the 190F propylene glycol heat transfer fluid and began leaking. I called HydroHot and asked them why an $8K heating unit has cheap plastic parts. Never did get an answer. But they sent me an all brass/copper replacement as I was just under the warranty by a few weeks. The same scene exists for the tank drain valve and piping being cheap plastic parts. I replaced that one myself. The hot water out connection also was a cheap plastic part which developed a leak. I replaced that with a SS braided hose. All three of these areas developed leaks. Fixing these leaks did help monthly fluid consumption but didn't stem the flow completely. I searched high and low for answers as to where the fluid was going. I also inspected piping and hoses and found no leaks. No one seems to know anything to include HydroHot themselves.
I did locate an interesting bit of information about silicon heater hoses, however. It seems they are porous to propylene glycol. Without lab tests I can't confirm this but it seem plausible. If true this explains why a seemingly tight system still leaks. Something to consider if your system is deemed tight but fluid is being consumed. I deduced reducing the pressure on the system would help discourage fluid from diffusing through anything porous. As it turns out, this was true and I discovered it by accident dealing with yet another mysterious leak in the unit itself. Some comments about the tank, filler cap and overflow reservoir are in order.
HydroHot mimics what is used on car radiators. They maintain vapor above the heat transfer fluid, use a check valve radiator cap (13 Lbs) and have a hose connected to a vented expansion tank. There is one important difference that seems to have been overlooked by HydroHot. A car's radiator goes through heating and cooling cycles from room temperature to say 220F. The HydroHot heat transfer fluid stays at or near 190F and mine has done so for the past 4 years. We live in the bus full time. Thus the draw on the HydroHot expansion tank is much less than that of a car owing the vapor above the fluid not cooling enough to contract to negative pressure. Car radiator systems use pressure to increase the boiling point of the coolant beyond 212F and thus remove greater amounts of heat from the engine. Since the HydroHot runs 22F below the boiling point of water, its heat transfer fluid can run at atmospheric pressure. Thus eliminating the need for a pressure cap. In theory anyway.
If you examine how a pressure cap works you'll notice two gaskets that engage two gasket surfaces in the filler neck. The cap also includes a small SS flapper disc which acts as a check valve allowing fluid to pass in but not out. There's a small cavity between the two gaskets in the filler neck that contains the overflow tubing nipple. The check valve vents to this region. When the vapors in the radiator (car system) come down from 220F to room temperature this creates a draw on the overflow reservoir pulling in fluid that was displaced by expansion. Thus keeping the cooling system full. Without the temperature swing (HydroHot system) there can be no draw and hence no automatic fluid replacement. Here's what I did as an experiment.
I simply removed the lowest gasket from the filler cap. This is the smaller diameter of the two. This will cause the main tank to vent into the expansion tank through the overflow tubing. Make sure the overflow tubing connection is tight at its end points. Make sure the cap's top gasket seals properly. This reduces the system pressure to atmospheric which virtually eliminates silicon hose diffusion. Any other small leaks (if present) will bleed much smaller amounts of fluid. Main tank fluid can thus expand and contract into the overflow reservoir through the hose connection. Between summer and winter I've noticed about a 1 quart displacement so make sure you have that much extra space in the tank. My plastic tank is vented to the atmosphere through a drain hose that dumps excess fluid on the ground.
I've notice a significant reduction in fluid consumption and the main tank stays completely full. My system has been setup like this for the past two years. I'm not endorsing this method and offer it as "experimental". Proceed at your own risk and keep a close eye on things. I'm still chasing down a small leak which disappeared after I removed the system pressure. I haven't needed to add any extra fluid in many months now. And I assert why stress hoses, fittings, heat exchangers and other hidden plastic parts with 13 Lbs if it isn't necessary. As per usual comments, other experiences, suggestions, rebuttal, observations are always welcome. I'm no expert just another disgruntled traveler trying to simultaneously protect my wallet and enjoy life. Some days it just isn't easy.

At 10:35 PM 6/8/2011, you wrote:

Re: Hydrahot (aquahot) leak.

Reply #3 –
Yahoo Message Number: 71652
If by chance, Country Coach installed the No-Fuss Flush like the one that you can buy at $CW$ for about $16, I have heard that the secret to getting this gizmo to work good is to drill out all of the holes with a 1/8" drill bit. Obviously, you would need to remove it from the tank and if it is the No-Fuss Flush, it is attached with three screws through the flange plus RTV to seal it. Let us know how it turns out!

Glen w/SOB
 

Re: Hydrahot (aquahot) leak.

Reply #4 –
Yahoo Message Number: 72167
Scott,

Very interesting hypothesis ! The same thing is happening to my Hydrahot! Every time I use it I would have to put in over a quart of propylene glycol also. Still see no leaks. Interesting hypothesis that I will definitely look into. Thanks for your insight and knowledge in this matter. Way to go Scott! At least I know I'm in the same boat as the rest of you . Thanks again Scott I will look into the cap.

Scott Jones, 2004 Allure # 31094