single pole and humming questions - baseboard heat
I have a couple questions.
We moved into our house last April (2300 sq ft colonial-built in the 70's) and its ALL electric baseboard heat. This is our first winter and our electric bills are very high. Within the last couple of months I started replacing all of the thermostats because the old ones (ra=stat) would cause the room to get too hot then get too cold until it kicked back on and some would just stay on (I tried vacuuming dust out-nothing helped). Anyway, the only Honeywell thermostats I could find where double pole and all of mine were single pole (Honeywell techs told me how to hook them up for single pole use and they work great (very comfortable).
So here's some of my questions:
What is single pole exactly compared to double pole? Is it bad to have it that way (since it's not done anymore)?
Also, I get a slight humming (or buzzing) sound coming from my baseboards. It usually (but not always happens when the thermostats are off. If I tap them, I can sometimes make it stop. When the thermostat kicks on it usually stops, too.
Is this just some frequency hum? Does this have anything to do with single pole?
Thanks in advance.