Heater / Thermostat Question

redlightning

So, I fired up the hvac on the boat today since the temp is dropping for a few days.  Heat came on and warmed up the cabin easily.  It appears that the set point for the heat cannot be lowered below 65 degrees.  in addition, I guess I am going to have to get a remote temp sensor because the cabin got very warm and was only showing a temp of 61.  I am sure it was warmer.  this is after I adjusted the ambient temp up to the maximum off set in programming.

Anyway to get this system to allow me to lower the temp where the heat will engage?

raybo3

At 65 and lower you would be calling for A/C not heat. Raise the temp to 75 or higher for heat.

redlightning

yea I get that.  I could put the system in heat only mode in programming so the cooling would not come into play.  if its 50 in the cabin 65 will engage the heat.  I just don't see any need to keep the cabin above 40 or 50 degrees when not being used.  Simply wanting to keep it warm enough to not allow anything to freeze.

MarkB

Check where your thermo couple is (temperature sensor). Mine is behind the air return at the foot of the mid berth. It wasn't positioned well and was resting against a pipe. I moved it and put a quick tie on it and it helped a lot. 

Did you try calibrating the thermo couple? 

Michael T

@redlightening. I had a failed temperature sensor (looks like SS bullet)  on my new HVAC. The technician who installed the new one, installed it near the HVAC unit (for reasons that I fail to comprehend) so that when in cooling mode the HVACs chilling made the thermostat read too cool and shut off and when in the heating mode the sensor read too hot and shut off. So a good location for unobstructed air flow is very important. I had a friend experiencing trouble and it was as simple as making sure the bedspread did not cover the return air grille.

So, I repositioned my new temperature sensor behind and in the middle of the return air grille for a good "average temperature" airflow. Test your temperature sensor to make sure it is accurate (my first new one wasn't) and check to make sure it is in a good position to read average temperature airflow. If you have to replace the sensor, its wiring, on Dometic units, usually runs to the printed circuit board under a metal cover on your HVAC unit. It just clips-out like a telephone jack plug. Good Luck! :-)

BTW another problem some boaters have is the location of a thermostat itself - IF there isn't a remote sensor. My friend had "wonky" temperature swings caused by a thermostat that was installed on a place in his boat that was subject to heating. We cured that with a remote sensor install.