What type of air exchanger should I use in a 6,600 sf house in the cold mountains using radiant heat floors. Can I use one central exchanger. Will this provide the air that I need that a large range hood would pull from the house?

There has been a lot of discussion on the greenbuildingadvisor forum about this very subject. The consensus seems to me that for a large range hood a HVR/ERV will not provide sufficient "make up" air. Several suggestions were raised, I would take a look over there for additional information.

http://www.greenbuildingadvisor.com/blogs/dept/musings/makeup-air-range-hoods

Can I use one central exchanger

Yes, Heat or Energy Recovery ventilators operate in the range of 100 - 200 cfm. This is enough for even very large houses, unless you are also planning on having large numbers of people live there. They exhaust as much air as they bring in, so there is no net positive amount to provide makeup air for a "large range hood, which can be 600 cfm 1200 cfm or more. Even if a ventilator operated in a one way mode, bringing makeup air into the house, there would still be a big volume discrepancy. Essentially, you need to open a window or even have a dedicated makeup air fan come on when the range hood is drawing.