I just wanted to add that I'm still using the hot water coil setup, this will be the 4th heating season. They save me a lot of electricity by offsetting the power that the blowers on the furnace consume. The blowers use 300 watts each (total of 600 watts for 2 of them) a significant amount of power. My current bill shows that my electric is 13.3 cents per kilowatt total (total bill divided by KWatts used). During the shoulder months the blowers run part time. But for about 3 months they run 24/7.. Running 24/7 they use 432 KW per month and would cost $57.45.. My electric bill actually goes down in the winter months, even with the blowers on 24/7.. Actually the usage drops about 300-400 KWatts. Average 350 KWatts which would be roughly $45.00.. So overall they swing the electric bill about $100 a month the other way. The coils paid for themselves in just a few months.
The trick is to use an extra hot water tank to use as a temper tank that circulates thru the coil by natural convection. No pump required if done right. THe other trick is to keep it simple and use a set of three valves so that all you need to do is swing valves to activate the setup thru heating months, then deactivate it during the summer. You DO NOT want cold water in the coils thru the summer, it will destroy them!
I'd be happy to help if you have any questions on concerns