I have an RCS TR40 thermostat and whenever I change the heat set point down it's also changing the cool set point down the same relative amount.

Anyone else seen this?

I know about the thermostat keeping a 3 degree minimum between heat and cool set points but I'm actually making a change that's increasing the difference between the two and either the stat or the plug-in is actually maintaining the spread.

Interestingly, it happens when stat is in "auto" or "cool" mode, but not in "heat" mode. So I tested the reverse scenario - increasing the cool set point while in heat mode and it does *not* bring up the heat set point with it, which is what you want (well, I want, anyway)

Is this something the plug-in is doing or is it something the (my?) thermostat is doing?