Nice forum -- But a little knowledge is a dangerous thing!
20 years ago I had an Amana NG furnace and A/C unit installed in my house - replacing an oil unit.
It is that crazy unit with the hydronic wraped heat exchanger 94% - a/c unit was the best one Amana made at the time.
Unit was installed using the same basic ductwork (installed by the old oil people -who were real pros) House is wood construction typical two story box with a large one story addition in back. Well insulated - new windows etc.
Oil people set it up with three zones 1st/2nd/back room. System has been great -- In summer I can keep the 2nd floor cold and in winter the back room hot. Plus the Amana unit really put out hot air - nice after the oil changeover.
My mother now lives in this house and the furnace finally went - unlike many with this Amana unit I have not had any real problems. So I need a new furnace and I would think I should just replace the A/C since it is 20 years old. I did get an Amana replacement est. -- the better unit with SS heat exchanger VS motor and matching A/C - 2speed 3 ton
What is causing me to spend some time on this is as follows:
The house I moved to 13 years ago is a large two story brick cape with typical second floor wood dormers - built in the 50's - updated with a large room off the back. When I moved in it was oil- forced air -original unit with ductwork all over the place!
Newer 4 ton York A/C unit for the whole house
2nd floor was cold in winter hot in summer -- back room hot in summer cold in winter - a real mess!
I ended up changing to gas -- hot water for heat -- radiant/ runtal units.
2 ton A/C only unit in the attic for the second floor and using the 6 year old 4 ton w/airhandler for the rest of the house. I was told the brick construction on the first floor adds to the heat load in summer. load was 3.5 tons - as I remember.
The heat works great! - the a/c is just ok. I was talked into an Arcoair unit -the 2 ton -that had some problems and needs a charge every year. I questioned the atic installation -- but I had no choice at the time. The balance on the 1st floor/back room system is just not right, plus I think it is oversized for the space and I should have zoned the back space (talked out of it)
To add to all of this I am buying a converted church for a weekend house that has two old forced air oil fired heaters - with one 3ton 2 year old bryant 10 seer A/C unit that to my shock is keeping the whole place cool even in the 98 degree heat we just had on the east coast. The placed was spray fomed top to bottom when it was converted to a house 10 years ago -- but they used the old heaters with new duct work. No gas service in the area.
I know that this is getting long - but the cost of all of this is