Hydro Hot Elec. versus Diesel

[Tom Fisher]

 Hope everyone had a happy Thanksgiving.
 I am thinking about leaving the heat on in our coach, parked next to our house for the next month before we can leave for warmer climates. In CO the temps will be close to 0 with temps below 0  with windchill factor. Going to do some general maintenance on the coach. I am plugged into 220 50 amp. Setting temp at around 45 and bumping up only when working on. Will use diesel to bump up heat, but was thinking about just using elec. to maintain 45. Will elec. keep up and is it more expensive than diesel to operate during the 45 degree maintaining period, which will be more that the working on period.
2nd question - I tried to set my Xantrex to Power share 50 amp , and I could only go as high as 30 amp. I am on a 50 amp 220 volt circuit from the house. I know at this time I will not be needing even close to the 30 amp, but was wondering why it wouldn't go up to the 50? Probably only a problem next summer when I need both ac's but ---?
Thank you

[Bill Sprague]

Tom,

The electric portion of a HydroHot uses a heating coil identical to the ones used in domestic hot water heaters.  It is rated for 1400 watts, plus or minus a 100, depending on model.  That is the same as a consumer space heater on high.  If I remember right it is about 5,000 BTUs.  The diesel burner is about 50,000 BTUs. 

My rule of thumb is that the electric is enough for raising the temperature about 15 or 20 degrees.  If it is 50 outside, I'll maintain close to 65 inside.   I'll guess that if it is 0 outside, the electric only might keep your motorhome interior at about 15.

Since most "camp" in mild climates, the electric works pretty well and keeps the noise and smell of the diesel minimized.  But if it is "cold" there is not nearly enough capacity in the electric only system. 

Regarding price, I once looked up some complicated charts provided by the Department of Energy.  Generally, electric is cheaper than diesel heating oil, but it depends on the price of electricity. 

My fear using electric only is if there is a power failure or the element burns out.  I've had both.  If it is below freezing and there is no heat inside the HydroHot itself, it will freeze.  The repair is about an $8000 replacement unit.   The ONLY secure way to protect your HydroHot in cold climates is to pump it full of pink RV antifreeze. 

About the Xantrex.  It is not hooked to 50 amp 220.  In our motorhomes, the 220 is split into two 120 systems.  The Xantrex is on one of them.  In other words, it is actually wired to a single 50 amp circuit.  Off the 50 amp circuit, the Xantrex is feed through a 30 amp breaker.  All the Xantrex will ever get is 30amps of 120.  There is no reason for settings any higher.

The only time the Xantrex will draw close to 30 amps is if you plug in with nearly dead batteries.  It will work as hard as it can to charge them, and on mine, can consume around 25 amps for short while and then taper off.  Each AC uses about 10 or 12 amps with a short peak at start up.  Each is wired to one of the two 50 amp circuits.  So when you are plugged in to "50 Amp" power there is more than enough to run both A/Cs and the Xantrex. 

Call, write or email if you have questions.

[Karl Welhart]

Tom,

If you anticipate 0 temperatures, I would not recommend the electric element side of the HH.  Either use the diesel burner side of the HH or winterize you system per Bill's comments.

Karl

[David T. Richelderfer]

In my experience the electric element in the AquaHot will increase temps inside the coach to about 25 to 30 degrees over the outside temps.  Of course, it makes a great difference on coach size, slides out or not, good slide seals or not, outside wind, etc.  My rule of thumb is if I need more than 20 degrees or so of heating to maintain a non-freezing temp inside the coach, then I use the diesel burner and furnace system for heating.  Obviously, if I want the interior temp comfortable for living, then I use the diesel burner/furnaces when outside temps are much under 50 degrees.  If the outside temps are over about 50 degrees, then I can use the electric element and furnaces or roof heat pumps or both for heating.  Both the electric element and diesel burner supply heat to the furnace system, and both the electric element and diesel burner can be on simultaneously.  If the electric element can supply sufficient heat on those warmer days, then the diesel burner will not come on.  In my AquaHot the electric element's "turn on" thermostat is set to about 10 degrees higher than the diesel burner's "turn on" thermostat.  Thus, if the electric element can maintain the coolant heat to above the diesel burner's "turn on" temp, then the burner will not actuate.

Don't forget you have water lines inside the slide servicing the kitchen and in the basement servicing the bathroom, and water lines behind the basement water bay door.  Also, there is the waste tanks and their gate valves for emptying.  The basement is only heated by the furnace system, and in my coach seems to use alot of energy that the living quarters won't get.  Again, the basement is heated only by the furnace system;  the roof heat pumps only heat the living quarters.

Lastly, winterizing the coach doesn't cost much and can be done in 30 minutes.  Three or four gallons of RV Antifreeze costs under $20.

[Tom Fisher]

Thank you  for the info. I don't know if I have a different elec. element thermostat for the Hydro. Will have to check that out.