By "heat pump" are you referring to a system that uses an air handler and coolant lines? If so, please get a highly experienced installer. These systems are a bear to get correctly "balanced".

I do not think heat pumps are usually even allowed in condo buildings.So check that out for sure. As for the ducting unless you are adding more I can’t see a problem with using the old ones with a good cleaning.

Air conditioner - Goodman

HVAC contractors who come as a package with a general aren't always a top choice. Hard metal ducts can be physically cleaned but standards and techniques have changed so much in even recent years, they're likely to be quite leaky. Did they suggest sealing them?

I'd get a second opinion.

They are in boxes 1976

This duct may be split

Looks like crappy duct board. Is that what it is?

Is the $3K bid for hard metal ducts to replace duct board? If so, I'd go for it in a minute if the place were mine. Now's the time, the walls are open.

Old rigid ductwork usually had no sealer at the joints, or just dried up duct tape. Duct board was even worse. While the walls are open install new ducting.

I’m curious the pushback to a heat pump, they are very efficient in the south and the most common heating system in my area.

I’m also curious why the switch to a larger system. There is a tendency to oversize systems which makes them run less often which means they don’t remove as much moisture from the air. Did they measure your actual hvac needs or did they increase the size on a whim?

In the south it's not likely to be rigid duct work, most likely to be flex duct.

The duct board duct being that old I would replace as well. What ever you replace them with make sure you get R8 insulation on the duct work as a minimum.

Heat pump vs straight AC: Given Florida climate heat pump would rarely enter defrost mode. If heating is electric heat strips the operational savings while running in heat pump mode could be as much as 75% less cost than running via electric strip heat. This operational cost reduction is for entry level system.

Just switching to a heat pump alone and several cold winters can pay for the system.

I would avoid up sizing the unit and add new insulation to the structure instead.

I think 2.5 tons for a 1350 square foot condo is over sized. Are you upgrading the insulation as part of the renovation? If you are then you should be going smaller and not larger.

Where in Florida are you located? In humid climates an over sized AC will short cycle and have poor humidity control. It wastes energy and is uncomfortable.

Get a quote for upgrading to a heat pump. On a 2 ton unit it should not be a big price increase.

If you have duct board then rip it out and properly sized and sealed metal ducts. A few dampers could be added so the system can be balanced to have an even temperature in all rooms.

A new 2 ton system with new duct work will keep you comfortable in my opinion.

Do NOT up-size A/C unit on existing duct system...!

Not only are Return-Air ducts grossly undersized but also
filter rack areas are also grossly undersized…

This is Extremely Important when Sizing filter rack areas…! Time
to start checking filter airflow fpm velocities...!

NCI is the National Comfort Institute, Inc.; they say to
verify the pressure drop for that filter at the design CFM & velocity and
compare it to the available static pressure of the system, the pressure drop
through residential systems should not exceed 20% of the fans rated static pressure.
A .5" Rated system x .20% is .1" of pressure-drop...

However; then they show the various WRONG steps in Sizing
filters for the CFM airflow & fpm velocity required; the problem is that
they use the listed total square footage of the filter and ‘never figure the
actual open area or AK ‘of the filter, which makes a huge difference in
selecting filter sizes for a particular required CFM & fpm velocity.

After much figuring I have found that the ‘open-air or AK’
of the low pressure drop filters is at around 0.645%. .Return-air filters are
not 100% open-air; for example RA grilles at 400-fpm velocity have a usual
pressure-drop of .03” while cheap filters have around a .08 or.1” pressure-drop
at 300-fpm velocity indicating many times more airflow resistance…!

A typical 16x25 or 20x20 is a total 400-sq.ins. x* .645% is
258-sq.ins open-air Ak / 144 is (525-CFM / 1.791666-Ak is 293-fpm velocity);
that’s only 350-CFM per ton on a 1.5-Ton
A/C…!

That’s how we have to size filters to come close to the
manual D requirement of 300-fpm velocity… Some say use 250-fpm, I kind
of like 280-fpm as being okay.

If you decide to install new duct work, make sure they put cold air returns in each bedroom, not just a large return in the middle of the house. By installing air returns in each bedroom you maintain a good flow of air for a heat pump system, even if your family sleeps with bedroom doors closed. It does make a difference in comfort.

Bruce

Stick with 2 tons. Replace the ductwork. If the $3k is for sealed, insulated, metal ducts then go for it, but that price is too high for flexduct.