Ok - I am finalizing HVAC etc plans on new construction in NC (triangle). Cost is obviously an issue and our climate is relatively mild so dumping money into certain things doesn't make sense. Geothermal is not a realistic option given the lot. Things like orientation and design are limited by lot and covenants (and are already designed).

There are 2 solar hot water heaters that we have been quoted Velux at $6500 or so and another brand at about $5800. I know no specific details on model number/size of collectors etc.

We are doing energy star certification with blower test etc. The house is 3 levels with initially unfinished basement. Planning a 90% gas furnace with Seer 15 HP on the main floor with just HP on the upstairs.

I would like to do some solar heating. I love heated tile and was wanting to run some pex tubing in the master bath for solar run radiant (obviously limited area). I would also like to supplement the house heating with the solar system. We have a decent sized mechanical room that could store a lot of hot water. There are both state and federal tax credits on solar hot water.

Ok - my question - finally - can we put extra collectors on the roof and initially tie it into just hot water. Then after we move in - as I have time - tie this into a heating system? Radiant to a large portion of the house is too expensive. Wife would not allow radiators (except in the basement) so I would probably do water to air heat exchanger.