A matching Trane coil should be installed but first question I would want answered is whether existing furnace has a 5 ton rated blower. And what about idea of the larger AC condenser?

How was this arranged? Through the insurance company's agent? Or perhaps through one of these awful third party warranty companies?

Eventually homeowner will most likely have trouble. Perhaps this is a case of an unethical HVAC company akin advantage of a senior.

This makes me mad.

IMO

No this is just a big mess.

What is location?

What size home?

Ductwork most likely is not sized for a 5 ton.

Homeowner would be better served if used Trane was removed for a good basic 4 ton 13 SEER with matching evap coil.

IMO

We have serviced this furnace for years and it is a Goodman GPS 120 and if I remember right does have a 5 ton blower. From what I can gather the work was done by someone sent by a home warranty company. They did not give the homeowner anytype paper work. Simply showed installed unit got it running and left. I though his homeowners policy had arrainged this but after talking to him again found out it was one of the home warranty outfits. The whole setup is quite odd house is 1700 sq feet and the 4 ton unit was too big, however someone installed it along with the furnace to replace an old gravity unit was not the best installation but whoever did the work lucked out and setup worked fine kept house comfortable and the years we have been servicing unit it has given minimum problems, we have replaced the timed fan board and a gas valve over about 15 years, other than this just cleaned burners, oiled vent fan motor and cleaned coils. A higher effeciency setup would definitely be better but I doubt they can afford it and are stuck with the Trane unit. I want to do whatever I can to help them and would like to do whatever I can to make the Trane last as long as possible.

It sounds like it is a five ton a coil, if not you can install a five ton metering device. But like I say if it ain't broke don't fix it. Now if there are condensation problems that is a different situation .

Heatseeker, according to the home owner setup worked fine,no condensation issues, said his electric bill actually was a few bucks lower than with the old setup. I had him turn unit on and it seemed to run smooth and the amp draw was in proper range. The whole setup is quite unique have never seen such a cobbled up installation that worked well. When the old gravity unit was replaced someone left the old 8 inch vents in tact and made sheetmetal adapters to make regular vent pipe connects from furnace plenium. They also used the old gravity return which is located in a hall way, several grates are installed in room doors and as weird as it is setup keeps house comfortable and the utility bills are within reason. We have not changed anything on setup, have simply repaired and cleaned furnace. I would like to do whatever I could to help them keep the setup operating. I hate to see people get cobbled up work like this. However as heatseeker says if it ain,t broke, don,t fix it. So maybe it would be wiser to just wait and see.