There are extra costs to move a HVAC system. If the system is all electric it's a tad bit easier. If it's gas, it's more complicated and costs are higher.

When you relocate the HVAC you have to relocate all the connections, duct work, flue pipe, gas piping, electrical, air returns etc.

Because this is a design related question, yes it can be done but it is best done from a blank slate meaning when the structure is built or take everything out and redesign the entire system duct work, everything. That can be quite costly.

So if your plan is to build a new structure the costs are even higher because you also have the costs of the new structure to contend with.

If you're not prepared with the costs of redesigning the entire HVAC system and just move it without considering design implications the next extended heat wave or cold snap may prove unbearable.

It's one thing for a HVAC system to operate in 80 degree weather or 50 degree weather --- it's quite another for it to work in 100+ degree weather or -40 below zero wind chills.

I've been in homes with HVAC systems installed in an exterior closet. But those homes were designed this way from the get go. So it's not anything new.

I service the Katy, Texas area

Thanks, really appreciate your advice.

what did you end up doing? I'm thinking about doing the same, mine is in a closet in the kitchen where space is a premium

There are two main cons to HVAC relocation:

https://www.heatair.org/

Difficulty

Relocating HVAC components can take a lot of time and labor, and it needs to be done by a professional so nothing is damaged and the system continues to work properly. If you’re having an indoor evaporator, outdoor condenser/compressor or a furnace/air handler unit moved, some of the necessary steps involved may include:

Pumping out the refrigerant and extending/replacing the copper lines.

Moving and leveling the unit.

Redoing the electrical wiring to the thermostat and/or disconnect box.

Removing any moisture in the refrigerant lines to avert flow issues.

Recharging the refrigerant and testing for leaks.

Modifying and reattaching the fuel lines, exhaust vent, and return and supply ductwork.

Performing various checks to ensure that the system is operating safely and properly once the move is complete.

Cost

The expense of relocating equipment can vary considerably, depending on the components involved, the materials needed, and the amount of labor it takes.

Be prepared for a lot of ductwork, gas line electrical renovation to accommodate your project, city permits will be required as it is not a simple retrofit. Best solution would be to speak to your local building inspectors and ask them what you would need to complete this project.