I am seeking for an advise on whether installing multiple heating zones have much sense in my situation.
At the moment I am planning to convert my house in Massachusetts from electric baseboard heating to natural gas. The house is a typical split entry with 1400 sf main level and 600 sf living space in the basement. The main level is going to be central air (heat pump plus hydroair) and the basement level will be hydronic baseboards. Obviously it gives me two zones already.
The question is if I will really benefit (cost savings as well as comfort) from setting up two central air zones for the main floor. I am thinking about separating my large (about 600 sf) living room area which has cathedral ceilings and large south facing windows from the 3 bedrooms. Because of the cathedrals and windows in summer the temperature in the living room might easily go to 90F while in bedrooms it stays below 80. Similar in winter cathedrals result in much more volume to be heated.
When I spoke to contractors in my area they generally advised setting up just a single zone claiming that having two will not make much difference to justify an extra cost.
I have absolutely no experience with HVAC systems but to me it seems a bit suspicious that a single zone set up (and I assume single thermostat) will be able to efficiently handle such a difference in temperatures. I afraid that in summer my bedrooms will be super-cold trying to keep up with a living room and in winter I'll have same problem but with heating. At the same time I would hate to throw money away on something that I do not really need.
What are the general principles for making zoning decision? Any recommendations?
The equipment proposed by contractor is:
Carrier infinity 2 ton 17 seer 2 stage heat pump; 3 ton infinity variable air handler; 72MBTU hot water coil; 130K BTU high efficient natural gas boiler (also connected to indirect water heater)