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Old 05-16-2022, 02:20 PM   #1
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Truma temp sensor placement issue

The Truma temp sensor in our 2022 Coachmen Beyond 22RB is placed above the sliding side door and sees a very different temperature environment than the room temperature FireFly sensor mounted under the wall cabinets on the opposite wall. The FireFly sensor is the one used to display the room temp on the FireFly display panel. With a room temperature of about 68 degrees and the outside temperatures around 55 degrees, the Truma comes on at a Truma panel setting of around 63 degrees. So under those conditions, there is a 5 degree difference between the two sensor locations. So in order to get the room temp to about 70 degrees I would have to set the Truma to around 65 degrees. Of course the delta in temperature will increase with decreasing outside temps. As a result I need to tweak the Truma setting depending on the outside temp, whether or not a window near the sensor is open, etc. Unacceptable to me. Why didn't they use only one sensor or at least put both sensors next to each other?
Coachmen tells me they can't integrate the Truma and FireFly systems to the point of using only one sensor and that I'm the first customer to complain about this.

I'm considering relocating the Truma sensor next to the FireFly sensor. Have any of you ever done this kind of relocating and what was your experience with it? Thanks for your help.
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Old 05-17-2022, 08:49 AM   #2
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You might be the first person to understand the problem and complain about it.
Since you've got a brand new unit, have you checked with the dealer to see if they have a solution? If you decide to relocate it, be careful not to void your warranty.
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Old 05-17-2022, 09:31 AM   #3
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I think your problem will prove to be common with these systems. You are way ahead of me in understanding the cause. My new Beyond 22c li3 (4. 1/2 months old). The Truma temp setting vs ambient room has been a total guessing game. Have to set as much as 10 +- high to get desired room temperature. Now my A/C is is about 1-2 degrees difference. A/C thermostat is in rear under cabinet over couch. Heat thermostat is front above control panel. I will plead total ignorance when it comes to these solid state systems, I’m a very old Analog guy. Does the offset setting on the Truma heater have anything to do with this deviance, please don’t lol.
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Old 05-17-2022, 09:31 AM   #4
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Old 05-17-2022, 03:22 PM   #5
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The Truma sensor is absolutely the wrond approach: 1) there should be only one sensor, not two 2) IF you can't get around two sensors, then they should be right next to each other so they see the same temperature 3) it's mounted on an outside wall 4) with very little insulation 5) it's right above a door 6) it's near an openable window and 7) it's above a hot air outlet. Coachmen isn't even sure they will relocate it in the next model year. Truma doesn't want the FireFly system to control their product. FireFly didn't answer my questions when I asked them if their system could control the Truma. The dealer? Forget it.
So, we're on our own . Opened up the spaces below both beds and found a hidden path for a 17 foot cord to relocate the current sensor right next to the FireFly sensor, eliminating the different temperature environments for both sensor, something that should have been figured out and implemented by Coachmen in the first place. Using only one sensor would be even better but that would require Coachmen, Truma and FireFly to agree. I'm not holding my breath.
So, it's off to Home Depot or Lowe's for a thin twin cord. Where's Radio Shack when you need them? Oh, right, that's no longer.
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Old 05-17-2022, 11:18 PM   #6
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Spent a couple of hours fishing wires in tight spots, but the job is done. Two sensors within inches of one another. Seems to work fine now. I can give you more specifics if you want to do this job as well.
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Old 05-17-2022, 11:24 PM   #7
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Quote:
Originally Posted by 10thtp View Post
I think your problem will prove to be common with these systems. You are way ahead of me in understanding the cause. My new Beyond 22c li3 (4. 1/2 months old). The Truma temp setting vs ambient room has been a total guessing game. Have to set as much as 10 +- high to get desired room temperature. Now my A/C is is about 1-2 degrees difference. A/C thermostat is in rear under cabinet over couch. Heat thermostat is front above control panel. I will plead total ignorance when it comes to these solid state systems, Iím a very old Analog guy. Does the offset setting on the Truma heater have anything to do with this deviance, please donít lol.
As far as I can tell, the offset was introduced by Truma to compensate for a subjective feeling that cooling to 70 degrees for instance feels different from heating to 70 degrees. I have the Truma Combi, so no cooling, but the offset is still there with a very vague description of what it would do for me. With the Truma sensor in the wrong place I could use the offset, but it would vary a lot, so it would still be a hit and miss game. But that's all in the past for me now that both sensors are side by side.
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Old 05-18-2022, 08:28 AM   #8
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Adios

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So, it's off to Home Depot or Lowe's for a thin twin cord. Where's Radio Shack when you need them? Oh, right, that's no longer.
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Old 05-19-2022, 09:32 AM   #9
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As far as I can tell, the offset was introduced by Truma to compensate for a subjective feeling that cooling to 70 degrees for instance feels different from heating to 70 degrees. I have the Truma Combi, so no cooling, but the offset is still there with a very vague description of what it would do for me. With the Truma sensor in the wrong place I could use the offset, but it would vary a lot, so it would still be a hit and miss game. But that's all in the past for me now that both sensors are side by side.
I want to thank you for this thread. There must not be many of these newer Beyond li3 out there. For months I have searched several forums for info li3, Truma, 12v roof A/C you are the first to address this package specifically. I have a new 2022 Beyond 22C li3 AWD. It has the Truma Combi. I have asked dealer and coachmen service repís about heat and A/C thermostat location. I have been told heat is up front & a/c is in back, no mention of 3rd sensor or fire fly. Iím an old Vietnam area jet mechanic crew chief. I understand analog & very little about solid state.
My 12v A/C thermostat to ambient temp 1-2 degrees. Truma heat all over the board. Would this indicate a problem similar to yours?
At some point would like to discuss 12v A/C outside noise, if you would.
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