Hi. I am a new member and I want to be as specific as possible so I can get the correct answer. I have a GMP100-4 furnace working properly in my house. I need to know the heating capacity of this machine because I want to add a AC Coil so I can use a Condensing Units that I received as a gift from a friend. The condensing unit (Trane) is 3 tons and so I need to buy a 3 tons coil to add it to my GMP100-4 furnace. Someone told me that my furnace should be 3 or more tons to be able to add a new 3 tons coil. The condensing unit was only use for one year. My questions are:

1- How can I find out the capacity of my GMP100-4 Furnace?
2- since the condensing unit is from Trane and my furnace I think is from GOODMAN, can I by the coil from any of these two companies?
3 How much do you think it may cost me to have this work done by a licenced worker?

This furnace is good for up to four tons of air conditioning(3 ton is O.K.) it is 17.5" wide, so I would try and get a evaporator coil that is the same width, name brand does not matter, just make sure you get one with an expansion valve on it and the same refrigerant.
The price will vary greatly from one contractor to another and also the local labor rates.
Shop around and ask your friends for referrals.

Thank you very much for your answer.

Hi acetc. Thank you very much for your answer.