I have a 60 year old 1 1/2 story 1800 sf house with basement. Location is northern Kentucky. Little insulation and original windows with storms. Heat is a 150K gas Sunbeam furnace. Air conditioning is with a 3Tn Sears unit. I've had a furnace man look at it and am told that the ducts are pretty adequate for what I've got installed. I'm a good enough engineer to know that the main ductwork is not undersized that it will restrict airflow - maybe not correct airflow. Evidently the ductwork was replaced when the A/C was installed 30 yrs ago. There are some baffels in the ducts. Both the furnace and the gas water heater vent up the chimney and I would like to keep that arrangement. I don't want a "booger" on the side of my house. There are only three ducts to the upper level and the stairway is the return. Maybe some sort of fan with extra power to the second floor when the A/C is running? I've heard many noise storys about that and need suggestions.
I've gathered from a lot of reading here that I do want to get some form of dual heat - Heat Pump and gas furnace. Makes a lot of sense to me, even though I make most of my money as a natural gas producer.
Now, as I conceptualize what I want, I think I would want a system set up in somewhat this configuration:
Heat Pump Heat Exchanger / Air Conditioner
Blower / Fan
Furnace with plenum to add heat.
I'd like to get something in the 80% gas range so that I don't have to put that booggr on the side of the house. I'm not too concerned about absolute best efficiency. I do want to be able to enjoy the immediate effects of calling for gas heat and getting it. What I have now is not very efficient, but it sure feels good when I want it to make heat, or cooling.
My thoughts on that configuration of the elements are that I want to have the Heat Pump working as long as the Outside Air Temp is greater than XXX. It will add heat to the stream, maybe not enough. With a downstream furnace, controlled by some exit temp reading telling the furncce to operate, I can still get very warm air from the vents. If the Outside Air Temp falls below XX, the heat Pump will not be in the game and the modulating furnace will carry the full load. The thermostat should allow the homeowner to set that XX number for the Heat Pump shutoff. Probably in the 20F range that it will not be energy efficient to operate with .07 kwh costs here in KY. But I don't want to have an "One or Other" system.
I sure would like to have a few advice comments on what I need. Perhaps what I want is not within the normal factory options. However, if it is, I'm sure the knowledgeable people here will know how to configure it.