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Author Topic: Motoraid in Atwood Water Heater (Rialta)  (Read 295 times)

spramphi

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Motoraid in Atwood Water Heater (Rialta)
« on: August 24, 2017, 11:27:59 PM »
I made an important discovery that isn't covered very clearly in the Rialta User Manual or the Atwood user manual.  This would apply to most Motoraid systems in many coaches that use electric elements (not propane) or the heat from the motor.  As you drive, the water will heat up in about an hour or so.  Once you arrive or stop, hook up or run the generator, and then want to turn the water heater (electric) switch on - DO NOT!!
What I discovered was that the motor can heat the water in the heater hotter than the heater sensing unit allows.  So....when you turn on that switch - it trips the very cleverly hidden little switch - (breaker or overload switch).  Then, you have to get into the water heater and open up the access panel to find the little switch to push it back in (or reset).  I know where it is but the first time took over an hour of frustration.
RULE OF THUMB: Use the hot water that was heated by the engine first.  Once it fizzles to lukewarm - it is safe to turn the electric switch on.  From that point it should be fine.  Many people have this problem and don't understand what is going on.  CAUTION: the Motoraid water coming out is usually around 190 deg F., which is the same temperature that your Keurig Coffe maker puts out.  Instant coffee anyone?

John Canfield

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #1 on: August 25, 2017, 08:50:00 AM »
We have the same 'Motor Aid' water heat feature on our Horizon and we never ever shut off the electric heat element. When the water is heated by the engine coolant the electric element will stay off.

There is a caveat however about using the propane burner with the electric element - don't run both very long or you could overheat.
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
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Gary RV_Wizard

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #2 on: August 25, 2017, 08:53:13 AM »
Are you saying the hi-limit cut-off on the electric heat element trips?  I can see how that could happen if the heater tank is fairly close to the engine - that 190+ degree water probably doesn't cool much on the way to the heat exchanger, and there is no intervening thermostat to prevent continued heating from the engine. Atwood doesn't make the engine side, so it would be up to the RV builder to provide some control over that.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

John Canfield

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #3 on: August 25, 2017, 09:27:19 AM »
I haven't measured the water temperature of engine heating vs. electric element vs. propane, I should do that sometime. Our engine coolant runs around 210F and I doubt the water is heated to 210, that would be quite dangerous. That coolant take-off goes to dash heat and an exchanger in the hot-water heater. Possibly the water heater is last in line for circulation.

Now I'm curious, I'll ask my Winnebago guy about 'Motor Aid.'
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
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Gary RV_Wizard

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #4 on: August 25, 2017, 10:24:14 AM »
I'm curious too, John, so hope your guy can elucidate. Atwood doesn't provide anything except the heat exchanger tube on the tank - everything else in the engine/radiator plumbing is whatever the RV maker decides to do.  A Rialta is fairly small and the Motoraid heat exchange tube is potentially exposed to very hot water. And the longer the drive, the more the water heats up.

The electric ECO is designed to open (trip) if the regular thermostat fails to keep the temperature in the preset range. In this case the regular thermostat is already open, but the only thing the ECO can detect is that the water is very hot regardless. It then does its job and opens up.  The Atwood Op Manual doesn't really cover resetting the ECO, because it is assumed to be a failure mode rather than normal operation.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Mile High

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #5 on: August 25, 2017, 01:30:38 PM »
Hmmm, I've never had an issue, and the WH is usually the first thing I switch to electric when parked.  My WH is right above the engine compartment in the LR, in a cabinet in the rear bath.  John raises a good question, I wonder if the motoraid is valved with a thermostat to prevent pumping 210 degree water through it.
« Last Edit: August 25, 2017, 01:33:28 PM by Mile High »
Brad and Dory
2013 Winnebago Itasca Meridian 42E (new to us 2016)
2013 Jeep Wrangler Unlimited Sahara
FMCA 457993 / WIT W170238
Denver, CO

John Canfield

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #6 on: August 25, 2017, 02:52:47 PM »
Heard from my Winnebago contact. The heat exchanger in the water heater is only a few inches long and there's several feet of hose to further dissipate the heat, but there's nothing to specifically regulate the temperature. He said "I've never had a complaint" about the Motor Aid, I assume he meant water that was too hot.
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
Our weather

Mile High

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #7 on: August 25, 2017, 04:42:04 PM »
That thing sure does a nice job for only being a few inches long!   Love that feature by the way.  I could never keep LP lit on our 5er while traveling so we would show up with cold water.
Brad and Dory
2013 Winnebago Itasca Meridian 42E (new to us 2016)
2013 Jeep Wrangler Unlimited Sahara
FMCA 457993 / WIT W170238
Denver, CO

Gary RV_Wizard

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #8 on: August 26, 2017, 09:23:35 AM »
Heat the water up before you leave home and odds are it will be at least warm when you arrive. Most likely still hot. I've left a heater off overnight and still had decently warm water the next day.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Mile High

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #9 on: August 26, 2017, 12:26:10 PM »
That works if you have time to pre-heat and they do stay hot forever, but that rarely works for us.  Grab it at storage, throw in the stuff and go.
Brad and Dory
2013 Winnebago Itasca Meridian 42E (new to us 2016)
2013 Jeep Wrangler Unlimited Sahara
FMCA 457993 / WIT W170238
Denver, CO

JoelP

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #10 on: August 26, 2017, 12:42:12 PM »
Is motor aid only used in DP or is this also used in gas RVs?  I never paid attention to whether or not the water was hot after traveling.  I am not sure if there is motor aid in mine, but my electric heat has not been working for a while.  My assumption has been that the element has failed or has been covered with calcium.
Joel from San Jose

2010 Itasca Suncruiser 37F
8.1L Chevy Workhorse with Banks PowerPack
2016 CMax Energi Hybrid dinghy

Alfa38User

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Re: Motoraid in Atwood Water Heater (Rialta)
« Reply #11 on: August 26, 2017, 03:09:09 PM »
The make and model of your water heater will reveal if Motor Aid is part of the heater or not. It could be found in either a DP or Gasoline model RV.
Stu
Montréal, Canada 🍁
Snowbird, Naples Florida
Alfa Gold 38 (2000) 5ver (parked!)

"Of course I talk to myself, sometimes I need expert advise!!!"

 

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