.. wrote:
With the desired temperature set at 84 degrees, the room temperature
drops to 72 degrees before the heater comes on. Shouldn't the room
temperature stay within a couple of degrees of the desired
temperature?

The heater has 2 green LED indicator lights. Both lights flash
simultaneouly at 3 flashes per second which the chart says is "NORMAL
OPERATION - signaled when heating demand initiated by thermostat".

I'm no expert, but all of that sounds normal to me. You set the desired
temp to 84, the thermostat then switches and tells your the current room
temp which is 72, the thermostat is telling the heater that it is calling
for heat and the heater LED's indicate that is what is correctly happening,
and over time the room temp will gradually increase until it reaches the
desired temp that you set (84), and then the heater will turn off.