Hyra Hot system operation

[Grant Stanton]

Hi my Beaver had a aqua hot sytem and I'm familiar with how it works but I have wondered about hyra hot is it just the same thing but a different brand or is it a totally different system. If anyone knows help educate me please.

[Stan Simpson]

Grant,

Hydro Hot is the name Vehicle Systems used before changing their name to Aqua Hot. They are exactly the same. Parts are interchangeable.

Stan

[Joel Ashley]

Actually, as I understood it, Vehicle Systems made the AquaHot, then designed a unit with less capacity and cost for smaller rigs and called it HydroHot.  A few years ago they simply changed the company name to reflect their main product, AquaHot.

Other hydronic system names commonly found in coaches are Hurricane and Oasis.

Joel

[Bill Sprague]

We have a Hydro Hot.  Like Stan says it is the smaller, cheaper "entry level" model.  In use it varies in four ways:

1.  The capacity of the coolant tank is smaller so that using hot water on electric only consumes the stored heat quickly enough that showers can be shorter than desired.  I always turn the diesel switch on for showers.

2.  I won't make heat and hot water at the same time.  When it senses hot water use, the heat exchangers shut off.  One ex Beaver owner posted a fix with a short jumper wire and said it worked well.  But, I never tried it.

3.  On bigger units I think there are two cut in thermostats for the diesel and electric.  You can leave both switches on.  If the electric alone can keep up, the diesel does not light up.  In other words, the diesel backs up the electric.  The entry level Hydro Hot triggers both off the same thermostat and both heat sources engage at the same time.

4.  The Hydro Hot electrical element is a single, ordinary water heater element of around 1300 watts.  That is about the same as a small space heater but is the limit of a normal household circuit.  It is enough to keep things from freezing in 30 degree weather, but maybe not in 20 degree weather.  It may be enough to keep you warm in 50 degree weather, but not 40 degree weather.  On some, if not all, larger Aqua Hot models there are two elements and you have around 2600 watts of heat available.  That with the diesel in the backup mode, it is much more capable of keeping you warm without blowing diesel exhaust at your neighbor.

[Orman Claxton]

Hello Grant
Bill Sprague is pretty much right regarding Vehicle Systems, Aqua-Hot, Hydro-hot, they are all the same.
I have the system in my coach
I am also an Aqua-Hot  factory Trained and certified service center.
Please feel free to contact me regarding your system. I know there will be several questions even now you have.

[Grant Stanton]

Thanks for all the info, gives me a much better understanding now.

[Bob Jae]

Grand check out Roger Berke's forum  http://forum.rvhydronicheaterrepair.com there is lots of good reading there.

[Keith Oliver]

Orman,  as a new owner of a coach with an Aqua-Hot system i have a few questions.
When I turn on the Aqua-hot using the 110v switch, it seems to heat water quite quickly, but the space heat has only come on once or twice.  There is a button in the bathroom called Aqua-hot fan, which hasn't yet done anything when pressed, so i don't know what else needs to be happening before pressing it.  Is this system tied into the temperature settings on the air conditioner controls?  If not, where are the temp controls?  If on the A/C controls, how should the control be set for best results?
When I pressed the Aqua-Hot diesel, just to test it before we bought this coach, everything was cold and it came on right away.  When I pressed the same button while traveling,  but after using the 110v part, the diesel heater didn't come on.  I have gone no further, as I am dealing with other, more urgent issues.  Is this proper, normal behaviour?

Thanks for your expertise and help.

[Bill Sprague]

I'm not Orman, but I'll give it a try by explaining how it works on ours.  

The electric element creates a little heat inside the Aqua-Hot.  Turning on the diesel creates a lot of heat in the Aqua-Hot.  

When you run hot water some of that heat is transferred to the plumbing for dishes and a shower.

If you want to heat the air inside your motorhome, you have to turn the Duo-Therm thermostats to "Furnace" and set a desired temperature.  That tells the several heat exchangers (or radiators) inside the motorhome to run until the motorhome comes up to the temperature you've set.  Ours heat exchangers have a switch to make each fan blow at Off, Low or High.

With the Aqua-Hot using diesel, the thermostats to Furnace and the fans to Low, we can stay warm in very cold conditions.  Electric by itself might keep us warm if the outside air is about 50 degrees or better.  

[Keith Oliver]

Thanks Bill.  Much as I suspected.  I have to get up that learning curve soon so as to avoid asking too many dumb questions.

[David T. Richelderfer]

You have much to learn, Grasshopper.  But you will learn things as they are dished out to you per your questions.  You should not think you will learn it all, but you will learn specific things as you have occasion to need to know them.

In my coach the thermostats run all those heating and cooling devices.  You can operate the various devices from individual thermostats, but only one function at a time from each thermostat... meaning you can run a roof a/c xor (exclusive or) a roof heat pump xor a heat-exchanger furnace.  I have three thermostats... so I can run one roof a/c, one roof heat pump, and one heat-exchanger furnace all at the same time.  Of course, that would be silly... but you get point regarding the versatility of the heating and cooling system.  Another silly example, I can close the two pocket doors on either side of the bathroom, and cool the bedroom using the bedroom a/c while at the same time be heating the bathroom with the bathroom heat pump, and at the same time also be heating the living room with the living room heat-exchangers. Yes, it's all magic.

[Steven Hoffman]

Keith

A few more bits of information.  The thermostat inside the AquaHot that turns the electric element on and off is set at a higher temperature than the diesel burner.  If both electric and diesel turned on and the demand is low the diesel will not run as the electric element can keep up.

Engine preheating loop if you have one will heat the AquaHot boiler fluid while you are driving.

[Bill Sprague]

Keith

A few more bits of information.  The thermostat inside the AquaHot that turns the electric element on and off is set at a higher temperature than the diesel burner.  If both electric and diesel turned on and the demand is low the diesel will not run as the electric element can keep up.

Engine preheating loop if you have one will heat the AquaHot boiler fluid while you are driving.

Steve,

We have a 2003 version of a Hydro-Hot.  Back then, Vehicle Systems did not put two thermostats in the lesser Hydro-Hot models.  That was reserved for the larger Aqua-Hot models.  

[Robert Mathis]

Another thing to watch out for if you are in  a really hot area or running hard in the mountains, if your engine heat gets too high, it can overheat the Aqua-hot and trip a breaker in the unit. I had this happen once last summer on our trip to Alaska. Once I figured it out, all was fine.