Doug Grove

So as a control I rolled up the topper mattress I had over the rear cushions and removed the inspection doors over the furnace and observed for a few hours. I got the same or very similar short cycling as I did for all the other test I tried. So I think I am ruling out air flows at least for my case.

I have sent and email to customer support I hope they read it. Basically it points them to this thread I hope they read it. This is what I told them: I don't know if you are aware of this thread on your forum but someone should read it. You have a lot of frustrated customers: Furnace cycling on and off every 2 minutes I have this problem with the furnace in my trailer short cycling. . I have been working on this for a week now and it is driving me nuts. When my furnace needs to heat my trailer from well below the thermostat set point everything is fine. When my trailer is near the setpoint the furnace only runs for about 2 minutes at most. Subsequently, after a few times it may run a bit longer. I have the rear dinette set up permanently as a bed. I have wireless thermometers set up in my trailer. I note that at times the temperature under the king size bed has been as high as 95 degrees. The air in the furnace compartment, i.e. under the passenger side rear seat is always hotter then the air at the thermostat.. I have tried a bunch of things none has adequately improved the situation. First I have a carboard box converted to direct the heat away from under the bed. I have opened the compartment under the rear seat of the forward dinette, I have duct tapped the provided vent and at other times I have both open. I have a fan running fulltime under the bed. Since I have added the fan the temperature under the bed has dropped to between 10 degrees and 5 degrees above the set point. I have some experience with control systems in chemical plants and so I have been looking to see if I could make any sense of what might be going on. Is the fact that the return air supply is above the set point factored into the control algorithm. I would expect the return air to be below the set point in a proper installation. I find it odd that I have the differential set at two degrees but the furnace cycles on and off in a much tighter band of about one degree. I am wondering if there is any kind of advanced anticipatory control being used like PD or PID. The first factors in the rate of temperature rise, i.e. the slope of the curve and the second factors in that plus the area between the temperature curve and the set point. I think you have an engineering or design problem here and maybe it is time to send this thread to your design people if you haven't already.

I am having exactly the same symptoms. When starting from a cold temperature, i.e. more than 10 degrees below the desired temperature, everything is fine until the desired temperature is approached then the furnace cycles on and off. The forced air stays on but it is only being heated intermittently. Sometimes the furnace fires for just a few seconds. The outside temperature has fluctuated between the 19 degrees and the mid 60's. The rear dinette is always in the bed position. One thing I note is that my thermostat has Bluetooth and I understand this is relatively new feature, introduced in the last few months. I wonder if there is something different about the upgraded thermostat. It is hot under the bed. Which isn't all bad. 🙂 I hope we find solutions soon.