[jeff5may]

Considering your strategy thus far, I believe your money would be best spent on an energy audit and a smallish central air unit. Before you start sealing and/or insulating, call your local utility companies to see if they have any programs in place that give out incentives or services to determine your heat load and reduce it. Most utility companies will start you in the right direction for free. Also, they may pay you to install an energy-efficient air source unit or smart disconnect box.

Since your heating demand is most likely 10 times your cooling demand and your house bleeds heat, a heat pump unit would need to be much larger capacity than a straight cooling unit. Also, with winter temperatures well below freezing for days on end, you would need a ground or water source heat pump to maintain high energy efficiency year-round. An air source unit would be continually defrosting all winter long, wasting electricity.

The water heating option works basically the same as the Airtap unit, but it converts waste energy from the outdoor unit into domestic hot water. It isn't thermostat controlled, it scavenges heat into your domestic supply line when the unit runs during normal heating or cooling operation. Naturally, a heat pump unit will produce more hot water, since it runs year-round. A desuperheater is usually not even an option on straight cooling units.