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Topic: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ??? (Read 1036 times) previous topic - next topic

2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Does anyone know for sure what type of Aqua-Hot heat exchanger is in the dash?  Is it the same as the rest of the ones inside the coach (Cozy) or one of the big Komfort HX's?  Or is it something else.

I've tried to get to it to find out, but would have to disassemble the whole dash.  Not something I really want to do.

Thanks
Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #1 –
I would like to know, as well. I had assumed, a dangerous activity, that it was heated and circulated radiator heat. This, after reflection, does not seem very plausible, now.
No RV! Have hung up the keys.
In the past: 2016 Winnebago Era, 1994 Foretravel U240, 1995 Foretravel U240 (wide body), 1999 Foretravel 320, 36 Foot, 2003 Foretravel U320 38 foot,

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #2 –
If I had to bet, I would suggest it is radiator heated off the engine.  Otherwise you would have to run the Aqua Hot going down the road anytime it was cold.  And more likely the engine also heat exchanges the Aqua Hot for some small amount of hot sink water as well.  Doesn't the Aqua Hot heat the engine when required?  That would work the other way as well.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #3 –
There's a set of vents on the dash of 2003 U320's that are run by the AquaHot - they're part of the Zone 1 on the Dometic control under "furnace".  Now, they might also have engine radiator loop heat in them, but they are definitely tied to AquaHot heat operation.  I just don't know what model heat exchanger they use.
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: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #4 –
Those dash vents on my 2003 are exits for heat from the engine radiator (dash controls) for defrosting the windshield and heating the cockpit (understand this word no longer politically correct), depending on the direction of the louvres. Michelle has pointed out that they also provide heat from the zone one thermostat and the AquaHot. Like Jim, I still do not know if there is a heat exchanger there under the dash, however.
No RV! Have hung up the keys.
In the past: 2016 Winnebago Era, 1994 Foretravel U240, 1995 Foretravel U240 (wide body), 1999 Foretravel 320, 36 Foot, 2003 Foretravel U320 38 foot,

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #5 –
Oops! I just realized (1). There is another thread running with the answer to my dilemma. (2) I have hijacked Jim's thread, I am sorry. Still want to know what kind of heat exchanger is under the dash.
No RV! Have hung up the keys.
In the past: 2016 Winnebago Era, 1994 Foretravel U240, 1995 Foretravel U240 (wide body), 1999 Foretravel 320, 36 Foot, 2003 Foretravel U320 38 foot,

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #6 –
OK, I gave up and took the dash apart.  Here is what I found. 

Photos 1 and 2 show the insides of the dash.

1. There is only one fan.  It is a dual squirrel cage blower.  It is located just inside the metal box with the SGM label in Photo 2.  Air is directed up through the large vent opening and through other ducting attached thereto.  Photos 3 and 4 show a view down into the duct and back into one of the squirrel cages.

2. The fan has two sources of power - the normal dash air power when the ignition is turned on, and another controlled by the H1A wire from the Aqua-Hot when the ignition is turned off.  Two Hella relays (shown in Photos 5 and 6) perform this piece of magic.

I did not take the metal box apart to see for sure how many heat exchangers are inside, but I assume there are 3: one for the A/C, one for the engine heater, and one for the AquaHot.  I think it is obvious that cooling and heating are performed by different heat exchangers.  Some might think there is only one HX for heating, but this is not reasonable.  When you are parked and the engine is cold, there is no way to get heat out of the dash engine HX.  While the AquaHot does provide engine preheat, it is not sufficient to heat the engine coolant to the levels necessary for room heating.  Furthermore, with the engine off, there is no way for the engine coolant to get to the dash heating system.  So there must be a third HX hooked to the living room circulation system.

I think a call to James Triana is in order.

Oh, and why do I want to know all this?  I want to add some form of fan speed control to the dash AquaHot in a manner similar to the ones I have added to all the other AquaHot fans (yep, I did get them all done except the dash).
Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #7 –
Hi Jim,

I plan to do the same fan speed controller you are for the dash fan. Presuming the 2002 and 2003 coaches are the same, where do you plan to splice in the controller? Probably as close to the fan itself I'd presume. I'm hoping not to remove any more of the dash than I have to - maybe by removing just the touch latch center cupboard walls and roof? Hum...you're the pioneer on this so I hope you have a plan already.
Jim Frerichs
2002 U320 42'

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #8 –
Jim,

Thanks for the inside look.  There should be a power wire to each of the AH heat exchangers (dash, LR, Kitchen) that get powered when the Zone 1 thermostat calls for heat as does the zone 1 pump.  The power to the dash heat exchanger gets cut (probably with a relay) when the ignition is on.

My idea is to use a single speed controller in a common  power line that feeds all three.

Roger Burke says the Cozy heat exchanger draws only 1/2 amp.  The Komfort heat exchangers draw 8+ amps.  The LR and Kitchen HE in my 2001 U320 appear to be Cozys.  No sure what is in the dash.  If it has an AH heat exchanger with no fan and the AH powers the squirrel cage fan through the relay then a common speed control might work.  If the amp load on the dash fan is much different from the other heat exchangers then it might need a speed controller or its own.

I hope a single controller will work. It would be nice to have a single control.

Let us know what James has to say.  I have been studying the FT wiring diagrams.  I'm lost.  There may be a wiring drawing that I don't have.  Imagine that.

Roger
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #9 –
Roger,

It will not be possible to use a single speed controller for all the living room and kitchen fans.  You can control all the Cozy's, because their fan motors receive their power from the same source - the Zone A Relay inside the Aqua-Hot cabinet.  However, the dash blower motor does not receive its power directly from the Aqua-Hot.  The Aqua-Hot simply activates a relay that routes power from the coach circuit breaker board (on my coach it is B45) to the blower motor. 

Also, you have to connect the PWM to both the positive and negative wires to the motor.  For inductive loads like a motor, you cannot just install the PWM in the positive line.  Read about snubbers for more info.

Jim,

I was hoping that I could figure out a way to use the normal dash fan speed control when in the Aqua-Hot mode.  Hopefully Triana can provide some wiring diagrams that will help.  Also, without knowing more about the motor wiring, I would be reluctant to simply install a speed controller at just any old place.  If I get a solution, I will post it.  Right now, the best I can do is put in a switch that would allow turning off the dash blower during AquaHot operation.

Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #10 –
Well maybe I'll have to use two speed controllers.  The kitchen and LR heat exchangers have the positive 12v line from the AH controller and a ground wire returning to the AH case.  The speed controllers are cheap enough that if in the worst case I need one on each it wouldn't be a cost issue.  It would be nice to have a single point speed control.

We learn so much from each other and each others thinking.  Thanks everyone for sharing ideas and discoveries.

Roger
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #11 –
Jim,

It would seem that because the speed controller you ordered online and the dash fan both have positive and negative connections, then installing the controller on the the fan wires would do the trick (for either aqua hot or engine heat speed adjustment). That would allow the factory positive and negative lines to be switched by their respective relays as originally designed.

Or... maybe it would be far easier to use two speed controllers for the dash fan adjustment - one from the aqua hot side and one from the engine heat side?

Yes, a schematic would be quite helpful.
Jim Frerichs
2002 U320 42'

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #12 –
And here is the schematic courtesy of the kind people at SGM.

According to my interpretation of the schematic the AquaHot mode runs the blower fan on low speed only.

The blower is a 3-speed, 4-wire DC motor only available from SGM.  There are no details on the motor design.  I would guess there are multiple windings to achieve the 3 speeds. 

It looks like there is no way to access the ground wires for each of the different windings, so a PWM motor controller won't work (at least in my way of understanding how a PWM controller works - I could be wrong).

You could use a rheostat to control the low speed, but that will require a heat sink of some type.

I think I will just put an on/off switch on the AquaHot mode (on the H1A line from the AquaHot).

So why would I want to turn off the dash heat, you ask?  Two reasons: 1)noise reduction, and 2) reduce AH on/off cycling.  The Dometic CCC is close to the dash (just behind the driver's seat), so it gets unduly affected by the dash heat causing the AH to cycle on and off frequently.

Also, I'm just a bit nuts.

Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #13 –
Hi Jim,

Oh darn...I can't open the PDF attachment - I've tried everything I could think of. Any suggestions?

I wouldn't give up on the use of PWM speed control - though I haven't received mine yet. If you have access to the H1A wire in the dash, why not use the black wire to the fan as the ground and pass the hot side through the speed control. Or will a common ground in the speed control be a problem?

Sounds as though you like numerous improvement projects just like I do.

Jim
Jim Frerichs
2002 U320 42'

Re: 2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or ???

Reply #14 –
I am not going to post any more to this thread.  The issue about what type of HX is in the dash is resolved.  We have now started talking about speed control, which should be moved to the other thread I started a few days ago.  Aqua-Hot Fan Speed Controller Install

I have new information obtained this morning from SGM.  I will post it in the above thread.

Jim
Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow