BTUs are BTUs. 410 cools just fine. If you get the same size unit, you won't know the difference. But don't assume that the old one is sized properly. A good dealer will measure your house and calculate needs, not just put in the same size.

OK, heres the info that I was given on both units: Goodman: 1-MBE1600-Air Blower 1-CAPF3743C6-Evaporator Coil 1-ASZ14036-3.0 Ton Heat Pump Condenser 1-Digital Heat Pump Therostat RUDD: 1. Untra Series Heat Pump UPQL-JEZ 1. UHKA Air Handler Digital thermostat It says install 15 seer HP 3ton R-410-A split system. Now whether or not my house needs a 3 ton or not I left that up to the dealer/installers. But my house was built in 1940, is about 1500 square feet, with NON-insulated windows, with non insulated exterior concrete walls. I do have quite a bit of insullation in the attic. This is probably the reason for the higher ton heat pump. That and trying to get to the tax credit. Both dealers claim that their units qualify for the $1500.00 tax credit. If not then I'm makin me a trip to Sears and just replace my 24,500but window unit with another and call it a day.

An HRV is required by code on all new homes in the US. This is for ventilation air. I have one, works great. See link. Costs less than solar. An ERV will recover moisture too as well as heat. If you do not have a sealed combustion furnace (2 pipes, intake & exhaust) and have a gravity furnace, a combustion air duct is required to supply air for the furnace burner. You can create a "cold air trap" by placing a box on the floor and dropping the combustion air duct into the box (No top). You may also be able to connect the Combustion air duct to the return duct to the furnace (Check code). Attach duct at least 10'0" away from the furnace soas not to crack the heat exchanger with the cold air. Connecting to the return also creates a slight positive pressure in the house reducing infiltration/drafts. Stay Warm! Dan Martyn Here is a link that might be useful: Broan HRV

I know nothing about why your home is not set up for central air. I can speak knowledgeably about split a/c units. We installed them when we lived in Thailand. They are remarkable, in that they usually feature a dehumidify setting, to get the moisture out without making it too cold, as well as a cooling setting. If they worked at 17 degrees from the equator during monsoon season and hot dry season they ought to work well in Washington state. We went with small units in each bedroom, so that we were only cooling the area we were in, and one larger 20kbtu unit for the entire downstairs.