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Topic: Aqua Hot electric vs diesel heat (Read 847 times) previous topic - next topic

Aqua Hot electric vs diesel heat

Quote from: Woody & Sitka –
Electric element heats to a higher shutoff temp than the burner, so I wouldn't leave it on for more than 30 minutes for the initial epoxy warming.
Off track due to this comment, but interesting to note.  I have noticed that the overflow bottle doesn't get as high towards the full hot line with just the electric element vs the burner, which makes me think the opposite.  I think the element in my 100 model is only 750w.  Will that still get hotter than the burner?
Keith
2003 U320 38' #6197

Re: Aqua Hot electric vs diesel heat

Reply #1 –
Going back to Woody's comment I was a bit surprised also.


If I recall correctly, you'll have hot water in 20 minutes with the diesel burner, but it will take a few hours(4-5) for hot water simply with electric.

Patiently waiting , will check again today.
I did have a small heater in the compartment initially for the first 24 hrs but it was not directly facing the repair, I was just trying to keep the bay warmer than outside temp of low 40s

Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Aqua Hot electric vs diesel heat

Reply #2 –
Also thinking on the electric vs. diesel temperatures, it might be a setpoint difference or a priority difference.  In our experience, if you have both electric and diesel switched on, the AH will only use the electric element to heat the boiler unless it can't keep up or achieve the desired rate of rise, in which case the diesel burner will kick on.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Aqua Hot electric vs diesel heat

Reply #3 –
Quote from: Michelle –
Also thinking on the electric vs. diesel temperatures, it might be a setpoint difference or a priority difference.  In our experience, if you have both electric and diesel switched on, the AH will only use the electric element to heat the boiler unless it can't keep up or achieve the desired rate of rise, in which case the diesel burner will kick on.

Michelle is correct.  The thermostat used to control the electric element is rated higher (190F I think) than the one used for the diesel operation (180F) I think.  So if you have both switched on and the demand is low the electric element will keep up with the demand.  Don't quote me on those temperatures but they're close.  I'm always a little uneasy about how hot the boiler fluid is at the first cozy heater heat exchanger on the loop.  There are a number of places in the coach where 5/8" heater hose is slipped over 1/2" pex with a hose clamp connection.  I once turned my Aquahot on and turned all of the thermostats up when the coach was stored outside in very cold temperatures and within a few minutes I had one of those hose connections come apart and start pumping boiler fluid into the living room under the cabinet.  The only thing I can attribute this to is rapid expansion of the tubing.

Sorry if a little off topic.
George Mann
2002 U320 #5934
2017 Rubicon
2013 BMW GS
Waterford MI

Re: Aqua Hot electric vs diesel heat

Reply #4 –
The older heaters with two control thermostats work as described above.  But the new ones, Hydro Hot or 400 series and 600 series have only one thermostat.  They also have an electronic control board or more recently, a Reporter.  These turn all the heat sources enabled on and off at the same time.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Aqua Hot electric vs diesel heat

Reply #5 –
Rather than derail the other AH thread about the leak, I thought I'd start a new one instead. 

Quote from: Geodmann –
Michelle is correct.  The thermostat used to control the electric element is rated higher (190F I think) than the one used for the diesel operation (180F) I think.  So if you have both switched on and the demand is low the electric element will keep up with the demand.  Don't quote me on those temperatures but they're close.  I'm always a little uneasy about how hot the boiler fluid is at the first cozy heater heat exchanger on the loop.  There are a number of places in the coach where 5/8" heater hose is slipped over 1/2" pex with a hose clamp connection.  I once turned my Aquahot on and turned all of the thermostats up when the coach was stored outside in very cold temperatures and within a few minutes I had one of those hose connections come apart and start pumping boiler fluid into the living room under the cabinet.  The only thing I can attribute this to is rapid expansion of the tubing.

I have the AHE-100-02S and I do know that with the electric element enabled, the coolant reservoir comes up about an inch shy of the full hot line.  If electric has been on for a while, and I turn on the diesel burner, it will light and heat until the reservoir comes up to the full hot line, so it seems like the electric element isn't getting the boiler as hot as the burner will.

Are these control thermostats adjustable or might I have an issue here?
Keith
2003 U320 38' #6197

Re: Aqua Hot electric vs diesel heat

Reply #6 –
I believe that is the way it is designed and the thermostats are not adjustable.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Aqua Hot electric vs diesel heat

Reply #7 –
Quote from: WS6_Keith –
Rather than derail the other AH thread about the leak, I thought I'd start a new one instead. 

I grabbed the other side-discussion posts from that thread and merged them into this one.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Aqua Hot electric vs diesel heat

Reply #8 –
Keith, mine is just the opposite...sounds like the thermostats might be reversed or just off spec.  According to the 100-02S service manual, the electric thermostat (red dot) should open at 198deg and the burner thermostat (blue dot) at 190deg (I have a 180deg by choice).  I also put a wireless grill thermometer in between the tank and insulation to monitor the temperatures...they are spot on...diesel : 180, electric : 200ish.

My heat up times from cold are the same as Frank's.  I don't heat to cut-out on electric when on generator...just hot enuf to shower, don't use electric often, and never leave it on continuously...I had both an electric thermostat and breaker thermostat fail to open/fuse, and steamed out all my coolant a few years back....good thing I was there and heard the gurgling racket and shut it down before it blew my coach in half.

Over the years all sorts of changes in suppliers, and yes I mean "those guys", could be affecting our different experiences as well.  As long as the thing makes hot water, I am a happy camper...literally.  And when Rudy retires, I'm selling the coach and getting a propane model!!!

2001 4010 U320 build #5865 "Bluto-d-Bus" since 09/18
2006 Honda Element ESP Toad
Full timing since 2016 in Western MT
Copilot: Sitka
1975 GMC 260 Avion: sold

Re: Aqua Hot electric vs diesel heat

Reply #9 –
I'm sure there are variations in the controls for different models and years. Get the service manual-schematic and see how it is wired.
For my Oasis, the water thermostat is operating a relay. The burner and heating elements are switch on and off together. Observing it I think they missed an opportunity for better recovery performance. In a typical boiler set up there is a set temp range, and then a higher limit. When water is called, or a heat zone is activated the burner will immediately start and run until the high limit. This eliminates the cool dawn that occurs when the zones are off and burner shuts off on set point. When water is called for or a zone turns on the water cools until that set point is reached and then these is the recovery lag.
Dennis Haynes
Bohemia NY
2008 Nimbus 342 SE Carlyle
Build #6475
Motorcade #19148

Re: Aqua Hot electric vs diesel heat

Reply #10 –
Quote from: Geodmann –
The thermostat used to control the electric element is rated higher (190F I think) than the one used for the diesel operation (180F) I think.  Don't quote me on those temperatures but they're close.

From the service manual for the AHE-100-02s, the DC thermostat is 190F and the AC thermostat is 198F.  I'm still not crazy about running 200 degree coolant through PEX pipe.  I know it's rated for it (barely) but still seems like begging for trouble.  I would prefer it to be around 180.  I may look into different operating thermostats... or I might leave well enough alone.
George Mann
2002 U320 #5934
2017 Rubicon
2013 BMW GS
Waterford MI

Re: Aqua Hot electric vs diesel heat

Reply #11 –
Quote from: Geodmann –
From the service manual for the AHE-100-02s, the DC thermostat is 190F and the AC thermostat is 198F.  I'm still not crazy about running 200 degree coolant through PEX pipe.  I know it's rated for it (barely) but still seems like begging for trouble.  I would prefer it to be around 180.  I may look into different operating thermostats... or I might leave well enough alone.

I would leave it alone. The system in our 1995 U320 has performed perfectly.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186