Hydro-Hot Issue

[Don and Kathy DuCharme]

Cold weather revealed a new problem with our Hydro-Hot. None of the circulation pumps function thermostatically. The electric and diesel systems function normally to heat the boiler, so no problem with hot water. The thermostats function normally for AC, fans, and heat pump, but no response on furnace. We had the unit serviced last July at the Indy rally, and I thought perhaps the Tech. disconnected something and failed to re-connect but if so I cannot find it. The only light on the control board is the Electric Heating Element Status (electric turned on - diesel burner turned off). Cannot find a bad or loose connection. Unit is the Hydro-Hot HHE-200. Any suggestions will be appreciated.

[Steve Huber Co-Admin]

Don,
Helpful if you told us what model/engine/year coach and model of Hydro Hot.
Steve

[Don and Kathy DuCharme]

Steve, the coach is a 07 Contessa with the Cat C9, and the Hydro-Hot is HHE-200.  Thanks for reminding me to include this info.
Don

[Steve Huber Co-Admin]

Don,
Thanks.  When you set a thermostat to Furnace and set the temp above the ambient, the circulation pump for that zone should come on to pump heated antifreeze to the heat exchanger once the boiler tank is at 150F or higher. So, first be sure you are running on Diesel and give it some time to reach temperature. Once the circulation  pump comes on, the zone indicator on the Control panel should illuminate. (The boiler is normally at 190F if the diesel has been on for 10-20 minutes or the electric element for 1-2 hours).
Since it was recently worked on, I'd also make sure all the connectors inside the HH are seated.
Steve

[Don and Kathy DuCharme]

Problem solved. A lesson learned for those of us living in northern climes. A few weeks ago I evacuated the fresh water system to prevent freezing when we had a couple of cold nights. I know this is not an acceptable way to winterize the Hydro-Hot, which was protected by keeping the boiler hot by way of the electric heating element(connected to shore power). I appears that the fresh water system must be filled in order for the furnace function to operate.  If not filled apparently the control board senses a continuous flow of hot water.  I filled the fresh water system with the "pink stuff", and voila everything is fine. To quote a famous bard "all is well that ends well"!
Don

[Steve Huber Co-Admin]

Don,
Glad it's working but not clear to me what is going on. The HH manual states; "NOTE: The Hydro-Hot can still be used for interior zone heating even if the domestic hot water system has been drained and winterized."
Yet you noted that you had hot water, from shore source I assume. It would seem then that the HH should not have been sensing a continuous need for hot water, which would disable the furnace system.
Steve

[Joel Ashley]

I’m with Steve here.  I’ve had the Hydrohot on to heat the coach many times when the tanks were all empty over winter here by the house.  An empty water tank should have no bearing on HydroHot fluid circulation to the registers.

There’s still something askew that might cause another occurrence.

Joel

[Stan Simpson]

I second (or third) those esteemed gentlemen. I have our coach completely drained, with pink stuff in all cold and hot water lines (including the HH), and yesterday I heated it up with the HH because I was doing some work inside. When I went in, it was 22 out and 31 in; I managed to get it up to 49 in about a half hour or so.

[Steve Huber Co-Admin]

Don,
I think the problem may be related to the Low Temperature Cut Off circuit as it will not allow zone heating if domestic water is being used. You might want to check with the shop that serviced the unit and see what they actually serviced / replaced.
Steve

[Don and Kathy DuCharme]

Thanks everyone. Steve, I also suspect the low temp cutoff. As others, we have used the furnace function many times while the unit was "winterized', however, the fresh water system was always filled with pink stuff.  The difference this time was that I evacuated the system by blowing it dry (connected an air compressor to the fresh water input for an extended period of time.  Apparently, when the system is empty the furnace function is disabled probably related to the low temp cutoff (the low temp cutoff light was not activated). After I filled the system with the pink stuff and all was well the low temp cutoff light was activated along with others. Appreciate everyone's comments, we all continue to learn as long as we operate one of these beasts. If the problem emerges again, I will let you all know.
Don

[Bill Sprague]

This is an ethical dilemma   ...  Should I write it or not?  So, I'll write it in case some new to Hydro/AquaHot members are reading.

Don't do the air thing.  Do the pink stuff thing.  The reason is that even with a lot of air there may be enough moisture in the coils to dribble to the bottom and pool.  If then frozen, the repair may be the most expensive motorhome repair you'll ever have. 

Once we were camphosting at a state park in the spring.  A guy came in with a MH he borrowed from his brother.  His wife was not getting hot water and there was a leak somewhere.   Since we had a big motorhome he assumed I knew something and asked if I could help.   The diagnosis was easy.  Water was pouring out under the AquaHot.  I asked how he winterized it.  He said, "My brother has a diesel shop with a big compressor and he has always blown out the water on his RVs."  The brother had never owned a rig with a AquaHot.  It was new to them that year.  The camper said his brother could fix anything!  When I suggested the parts bill might be about $8K all I saw was confusion and disbelief. 

[Fred Cook]

I keep the hydra hot on when its supposed to get below 32.  I usually set the temperature at 55° when the coach is sitting idle at home on a cold night or day. We usually travel 1 to 2 weeks each month so it doesn’t make much sense for us to keep winterizing.

[Don and Kathy DuCharme]

Bill, I totally agree, DON'T do the air thing. I did it only as a temporary measure, and protected the Hydro-Hot by keeping the electric function active so the boiler temp was maintained above the 160 cutoff. By blowing the lines I prevented a freeze-up in other parts of the system. Best advice to everyone is to winterize the system by filling completely with antifreeze (the pink stuff).
Don