Another issue with a Truma heater.

[Buddhabelly]

Everything seems to work fine except one place and that's the temp control.  After I set the temp the furnace keeps running and doesn't turn off when it reaches the temp I set. Never had this issue before.  My guess is the temp sensor has gone bad but, I can't seem to find where it's located. I can turn the furnace off manually.  Does anyone have any suggestions on where to look and how to check to see if it works correctly?  

[jd1923]

Hull #? Signature? Please update asap...

Edited Saturday at 05:36 AM by jd1923

[topgun2]

10 hours ago, Buddhabelly said:

Does anyone have any suggestions on where to look and how to check to see if it works correctly?  

Sorry but I don't have one of those "fancy" things.  But, I assume that you've submitted a Service ticket?

Bill

[Rivernerd]

13 hours ago, Buddhabelly said:

After I set the temp the furnace keeps running and doesn't turn off when it reaches the temp I set. Never had this issue before.  My guess is the temp sensor has gone bad but, I can't seem to find where it's located. I can turn the furnace off manually.  Does anyone have any suggestions on where to look and how to check to see if it works correctly?  

Do you have the CP Plus wall control unit for your Truma furnace?  Could you attach a photo of the display on the unit when the furnace is still running but the set temperature has been reached?

And, an update to your footer showing hull number, model year and installed options would be very useful to those of us trying to help.

[Buddhabelly]

Yes, mine is a Truma CP plus. I've tried different temps and it doesn't matter.  It justr keeps running past the set temp.  i.e.62 and still heating at 72 degrees. Need to turn if off manually.  I turned in a service ticket and can't get anywhere with them. They just don't seem to understand what I am saying. Finally gave up along with my AC problem. It you guys that saved my hide on the AC.  Forgot, it's a 2021 model Elite 1

Edited Saturday at 06:29 PM by Buddhabelly

[Rivernerd]

The photo of the cat is cute, but a photo of the CP Plus wall unit  display when the furnace is still running, when the temp in the cabin is beyond the set temp, would be more useful.  It might enable progress toward diagnosis of your issue.

[Buddhabelly]

My error.  This is a pic of my Truma and a pic of the temp settng running and a differnt temp gauge so the difference after running for awhile.  Was 70 degrees inside and furnace still running.  I can turn it off manually but, doesn't turn itself off when it reaches it's temperature. Any suggestions would help...

[Snackchaser]

3 hours ago, Buddhabelly said:

 Any suggestions would help...

Reading your post peaked my curiosity about the Truma, particularly from the mention of a Temperature Sensor. . .  which is typically part of the thermostat.  So I looked-up the Combi and sure enough, there is a Temperature Sensor that is separate from the control panel.

Accordingly, there is a temperature off-set adjustment in the control panel to account for temperature variances depending on where the sensor is mounted verses the room temperature.  Perhaps that was inadvertently reset, which could account for your temperature miss-match.  I’d check that first.  Review your manual for instructions on how to change the off-set.

I don’t know where the sensor could be mounted, but it shouldn’t be too difficult to find by following the wire from the unit. It’s probably a simple thermistor, basically a resistor that changes resistance with temperature change.  These are easy to test with a multimeter in the Ohms setting. If the resistance value changes with a little heat applied from your fingers, then it’s probably okay.   

Let us know what you find and good luck.  Cheers!  Geoff