General Boards > Technical Support
Hydro Hot Use
Bruce Benson:
Perhaps it can be figured out. The unknowns here are how efficient the burner is in converting the diesel BTUs to hot water and the electric used to run the blower/pump. I would assume better than 80% but less than 90% efficiency. I am adding two KHW of electric ($0.28 in this case) to the price of the diesel to pay for running the burner motor. You could try on both ends of the efficiency range but the result will probably lead you to the same conclusion at todays prices. The electric is near 100% efficient. You need to plug in your own costs per unit.
BTU x efficiency / cost = BTU per dollar
Diesel: 138700 BTU per gal x .80 = 110950 / $2.85 = 38,528 BTU per $
Electric: 3412.3 BTU per KWH x 1.00 = 3412.3 / $0.14 = 24,374 BTU per $
The size or number of elements (though I agree that you almost certainly have a single) should have no real effect on your costs. It is still KWH to BTU, just quicker with dual elements.
Bruce
Joel Ashley:
I can add that I just got my electric bill for last month, and it skyrocketed. The weather turned unusually cold here for a week or 10 days, and I kicked on the electric side of my HydroHot for the worst part of that period just as extra insurance to protect it while stored next to our house. That manuever was the only significant change to our normal electric use at home, so I have to ascribe most of the bill increase to the HydroHot. At 1800watts, it should be no surprise to me the element could really eat juice if left on long. We often, when traveling, use a small cube heater (750-1500 watts) which is an alternative that uses less juice, but is also less safe and may not fully warm the space in certain applications.
LEAH DRAPER:
Have 2008 38' Contessa and I guess I'll show my lack of knowledge regarding the Aqua Hot. I was not aware that there was an option to run it on either diesel or electric. If there is that option then I don't know how to run only on electric. Not sure I would on my own bill, but how do you do that?? I live in the Albuquerque, NM area and I have been running mine on diesel set to about 55 degrees so as to keep everything from freezing with temps getting down to 10-15 at night at times.
How about enlightening me. Not sure I'd run electric, but.........
Do the underbelly compartments get heated if only on electric??
Joel Ashley:
Hmmm. Leah, different coach models and years, and different AquaHot models, as well as other brands of hydronics, likely mean there are multiple configurations. I don't have as much experience as Gerald and others, but can say I have yet to see one set up only with diesel. Your 2008 Contessa surely has a similar configuration to our 2006 Monterey, with a panel of 3 switches together; one turns on the diesel, one the electric element, and one the pump that circulates hydronic heat to your engine to preheat it, on cold days, before travel. Yes, your storage compartments have heat exchange fan units that get hot hydronic fluid regardless of how the fluid gets heated, electric element(s) or diesel.
If you are at a campground with hookups and therefore have already paid good money for electricity in your site fee, you may as well switch on the electric element to heat hydronically, rather than waste diesel. The electric element, however, is not as efficient at heating the hydronic fluid as the diesel burner is, so for taking showers or washing clothes, especially with your thermostat on trying to heat the interior, you need the diesel side running in order to keep up. I commonly leave the electric and diesel switches both on to minimize diesel use, but it will kick in the diesel when demand exceeds the electric side's capacity to keep up. Plus, for a quicker heat up of a cold rig and/or water system, or for engine preheat, I make sure the diesel is switched on; the electric side is better for maintaining an already hot system, not for a quick initial heat up. But for periods of low demand for space heat or hot water, and when you are in no hurry, or for storing the coach with the thermostat at the minimal 40 degree setting, you can save diesel and have only the electic switched on. My experience with temps as low as 13 degrees outside, the electric kept the coach interior at 40 degrees just fine, protecting anything that might be susceptible to freezing.
I'm surprised you haven't found the electric switch; it should be right next to the diesel one. You should read the HydroHot or AquaHot section of your Beaver owner's manual, and then the AquaHot Corporation's (formerly Vehicle Systems, Inc.) manual for your system that should be filed under "Furnace" or similar in the box of individual manufacturers' manuals that came with your coach. You should have been shown the full functions of the system by the dealer at delivery, if a new coach. But I am confident there will be other forum members with Contessas similar to yours that will be chiming in to help. ;)
Tom Rogers:
You should have received a manual that describes the operations as well as maintenance. If not, contact AquaHot and have them mail one or ........ go to their web.
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