Commercial HVAC replacement and installation in New Orleans.

Most buyers land on one of three paths, and the cheapest one on paper is rarely the cheapest over ten years.

Replace-on-failure is usually the default by accident. The unit runs until it dies, generally in August, and then you buy whatever is available instead of what fits. Planned like-for-like replacement fixes the timing problem but carries the old sizing forward, including any mistake the last installer made.

The third path is a planned upgrade: confirm the load first, then step up the efficiency tier or change the heating source. Federal efficiency work pushed manufacturers to build rooftop units that cut energy use by up to 50 percent against the older standard, and that gap is where the operating savings live.

Which path fits depends on how long you hold the building, what an outage costs you, and whether the space is still used the way it was when the old unit was sized.

No two roofs price the same, and the spread usually comes from five or six places rather than the unit itself. Ask for each of these as its own line so you can compare bids that look different on the cover page.

Start with what the building needs today. A twenty-year-old nameplate tells you what someone calculated for a different tenant, different lighting, and a different plug load. A fresh load calculation is cheap next to buying ten extra tons you will pay to run for the next two decades.

Then pick the heating source, because that decision drives everything downstream. A gas-fired packaged rooftop unit and a heat pump rooftop unit look nearly identical on the curb, but the heat pump reverses its cycle to heat instead of firing a burner. Heat pump rooftop units are best suited to mild-to-moderate winter heating, and across most of the South and West today's units are fully capable of covering most or all of the winter heating demand. Dual-fuel versions keep a gas burner for the cold snaps that even southern climates get.

Last, check what the site can actually support before you fall in love with a model. Electrical capacity, physical clearance on the roof, and existing gas lines decide more of these projects than efficiency ratings do. So does equipment availability. The unit you can get in three weeks may beat the unit you can get in twelve.

Two replacements at the same tonnage can finish a week apart or a season apart. The difference is usually access, electrical headroom, and whether anything about the system changes besides the box.

A quote written from a nameplate photo is a starting number, not a price. It gets you a tonnage range and real lead times, which is genuinely useful when a unit is down in August. It does not tell you what the roof, the panel, or the parking lot will add.

The walk should produce four answers. First, the load the space needs now, calculated rather than copied off the old plate. Second, whether the existing curb accepts the new unit or needs an adapter, and whether the structure carries the weight. Third, what the electrical service has to spare, because that single number decides whether an all-electric option is on the table at all. Fourth, how the crane gets in: reach, staging, and the hours you are allowed to close stalls.

Ask about the old refrigerant too. Recovering it from stationary equipment is federally regulated work, and it belongs on the quote as named scope rather than surfacing later as a change order.

New Orleans handles this through the mechanical A/C permit application, and one line on that form shapes your bidder list: only City of New Orleans Class A licensed mechanical A/C contractors may apply for this permit type. A contractor without that license cannot file for your replacement, whatever the price says.

The form treats replacement as its own project type alongside new construction, alteration, and demolition, and it notes that electrical, plumbing, heating, ventilating, air conditioning, and mechanical equipment each require separate permits. A rooftop swap that also touches the panel is more than one filing.

When the work counts as new construction or substantial improvement, the contractor attests that heating and cooling equipment is sized to ACCA Manual S using loads calculated by ACCA Manual J. Sizing stops being a judgment call and becomes something signed for.

Equipment choice is the visible decision. The two that follow you for the next fifteen years are how the unit gets serviced and who pays for what.

New commercial equipment ships on different refrigerants than the units it replaces, which matters less on day one than it does in year three, when your service contractor is stocking parts for a mixed roof. And in a leased building, the split between landlord capital and tenant operating expense decides whether the higher efficiency tier is worth arguing for. The party paying the power bill is not always the party buying the unit.

Buildings rarely have one rooftop unit, and replacing five at once is a capital event most owners cannot schedule. Phasing works better when it follows condition and load rather than age alone. Rank the units by what they cost to run and how often they fail, replace the worst two this year, then reuse the same engineering and rigging plan for the next pair.

That approach has a track record. Under the federal advanced rooftop unit campaign, more than two hundred public and private organizations upgraded over forty-three thousand units and cut a combined thirty-seven million dollars a year from their energy bills. Those were portfolio owners doing exactly this, replacing on a plan instead of on failure.

Procurement matters as much as selection. Order early enough that lead time is not quietly designing the project, and schedule the crane against a delivery date you trust. If a unit is already limping, decide now whether you accept a temporary rental during the gap or carry the risk. Deciding that in advance costs nothing. Deciding it during a heat wave costs plenty.

Bids that differ by a wide margin usually differ in scope, not in price. Make every quote answer the same five questions and the comparison gets simple.