Hydro Hot Use

[Jim Shaw]

I have a Hydro Hot system in My 2003 Beaver and are using it on electric only for my heat and hot water. In talking to my neighbors, my elect bill seems to be much higher than there's. Has anyone checked diesel vs electric. We are in Arizona for the winter and the temps have been in the low 40's to high 60's to low 70's. I am happy with the Hydro Hot's ability to supply hot water and heat, but would like to hear other experences.
Jim
2003 Monterey

[George Harwell]

I have the same system in an 03 monterey and it has a single heating element. Are you sure your system is the hydro hot as the AQUA-HOT has dual elements and therefore uses much more power. I have no knowledge about the electric bills but my landlord isn't complaining. I use a VORNADO heater in the living area and use the hydro hot in the bedroom on cold nights. Rarely have to turn on the diesel burner. You may need to investige things further if your bill is running consistently 50% or more than all of the neighbors. I don't know the details but your neighbors could be using propane for heat and hot water so all things considered it could equal out. Have a great day!

[Richard And Babs Ames]

Your owners manual for the Hydro Hot will give the wattage used by the electric element and probably is at least 1800 watts. A 'Hot Stick" sometimes used in a LP water heater is 6000 watts at most.  

Remember you are heating both the coach and hot water and your neighbors are probably using propane to heat their RV and water so add their propane cost to their energy cost to get a true comparison.

[Orman Claxton]

Your Hydro Hot uses  1650 watt element, just like the element used in your home hot water heater. This will draw 10-12 amps while turned on.
The dual elements are only used in certain units, I doubt if you have dual elements, I would need your model # to supply that info.
To calculate your useage elect. Vs diesel, a lot would depend on diesel price.
Thanks
Orman Claxton
206-660-9893

[Joel Ashley]

If you have access to your electric meter and outside ambient temperatures are expected to be fairly consistent for 10 days or so, I'd use the HydroHot's electric side only and read the meter at say noon on day 1 and again at noon of day 6 (5 complete days).  At that point turn off the electric side and use only diesel, then take a final meter reading at noon of day 11 (another 5 days).  The difference will give you an idea of how much the HydroHot affects your total electric bill, assuming appliances and all other electric use can be kept relatively consistent day to day over the entire timespan.

You could use a much shorter overall test period, even just a couple days, but the 10-11 day span would provide more accuracy.

Joel  

[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.

[David Fischer]

I have a 1997 Beaver Marquis witha Aqua Hot and I was told by the Aqua Hot people many years ago, that below 40 degrees the electric will do a very minimal job and the diesel burner should be on.  I have found that to be the case after 11  years using it. We are full timers an have property in Norther NM where we use the electric quite a lot during the winter.  Even using the electric and the diesel add up to an unexpected figure.  We have found it cheaper to go to the NM State Parks and use their electric.  

Merry Christmas to all
David and Sharon

[Ken Sair]

We have a 2007 Contessa with the Hydro Hot. Have been recently in northern CA where temps were in the low 40's and high 30's overnight. HH on electric was iffy at best. In the evening it would run on electric but the furnace would cycle off and then back on when the water temp recovered. Seemed like a waste of time to me and not very effective. Just my thoughts.

[Bruce Benson]

Can't speak for all models, but the way mine works is this.  There are two temprature sensors on the Aqua Hot boiler body.  One controls the electric and one controls the burner.  The electric is obviously set at a higher temperature than the burner.  If the use is low, the electric will maintain the temprature above the set point for the burner and the burner will not run.  Thus, if I keep both on and do not use any furnace heat and don't run a lot of hot water at once, the electric can keep up and the burner never burns.  On the other hand, if I do use a lot of hot water or more than a little furnace heat, the burner will kick in assuming the switch is on.  At this point both sources are being used at the same time to provide the heat.  

Again, I am just packing BTUs into the boiler, the source is not a factor.  The rate that the electric is packing them in would not change with temperature, the rate the burner packs them in might vary slightly with temperature.  The electric does have a lower output capacity though and will not keep up with the needs of the furnace by its self, thus the comment from Aqua Hot about the 40 degree threshold.        

Now, if I am using much furnace heat with this set up, the electric is almost always being consumed.  Who is paying for the electric should have a large bearing on whether to use electric or not.  It would probably be wise to just turn the electric off and use the burner when I am paying for the electric.  The real world is that I have always just left both on.

When I am not paying for electric and just using the hot water, I keep the burner switch off to avoid having it run should we use a lot of hot water at once.  The exception to that is when we do not have any power or we have less than 50 amps, in which case the burner is on and the electric is off.  We do often flip the electric on at night with 30 amp power assuming that the battery charger has reduced its consumption and we will not need cooling,  Remembering to turn it off in the morning before hair drying and microwaving is sometimes a challenge.

It is also a good idea to turn the burner off (and electric if you are paying for it) just before or right after the morning shower on travel days.  The engine heat will catch it back up once on the road.  I often leave the engine preheat on when traveling to assist in keeping the Aqua Hot warm.

Bruce  

[Joel Ashley]

Forgive me if I'm mistaken Bruce, but I was led to believe the engine contributes to the hydronics automatically whenever it runs, and the Preheat switch is only to warm the engine prior to starting it.  I think the Engine Preheat function is an essentially seperate system involving its own pump and/or valve(s).  Leaving the Preheat switch on when traveling is unnecessary.

[Tom Rogers]

Forgive me if I'm mistaken Bruce, but I was led to believe the engine contributes to the hydronics automatically whenever it runs, and the Preheat switch is only to warm the engine prior to starting it.  I think the Engine Preheat function is an essentially seperate system involving its own pump and/or valve(s).  Leaving the Preheat switch on when traveling is unnecessary.

That's my understanding also. We use the engine/water to heat the coach when on the road. Switches off. Stat on.