If you are planning on solar down the road, why not upgrade the current system so that it is a backup to the solar system?
First of all, I will not let a plumber tell me my heating requirement needs. I would call an HVAC contractor. One of the best in the area is Jeffery Seymour on Gilford Ave in Laconia. He is extremely knowledgeable of the latest in gas appliances. He is honest to a fault, he was a minister.
In my case, I had a plumber talking me into converting to an oil furnance with a seperate hot water holding tank. Big Bucks! I already have a NG furmance and an electric hot water heater.
Jeff installed a tankless NG furnance and domestic hot water. It is so small it hangs on the wall. It is so efficient the flue is PVC piping. I am extremely please with the system. Instead of cycling off and on the heating, it senses the outside temperature as well as the inside temperature and adjust the forced hot water temperature accordingly. Pretty slick!
While he was at it, he exended the gas lines to the kitchen stove, the clothes dryer and the fireplace. After swapping my appliances my electric bill was cut more than half, while I did not notice that must of an increase in my gas bill.
