HVACSouthwest OhioCincinnati

Hamilton High School Air Handler 2026

The north fine arts wing at Hamilton High School went into the 2026–27 school year with two new rooftop air handlers and a new roof beneath them, all replaced in one summer while the building was empty. Prodigy delivered the whole package under one contract: HVAC engineering and equipment selection, a new structural steel platform, crane work, chilled- and hot-water piping, ductwork, Automated Logic building controls, and an 80-mil Carlisle TPO roof carrying a 30-year warranty. Hamilton City School District bought the work through the TOP-C cooperative, a competitively bid unit-price contract, which let the district approve the project in November 2025 and have the air handlers on order by the first of December.

The air handlers and the roof were due at the same time, and doing them together is what made the schedule work. A crane took the old units off in early July and set the new ones the following week, while the roofing crew worked through the wing's roof sections around them. Because the new units stand on steel above the roof, the new membrane runs under the equipment instead of around an old curb, and nothing will have to be lifted off it when the roof is next worked on. The crew also removed 18 abandoned curbs, filled in the deck, and added tapered saddles to drain an area that had been holding water.

The new equipment is two Daikin Rebel air handlers of about 27 and 20 tons, serving the wing from the school's existing chilled-water and hot-water loops. Both run variable air volume with an economizer that uses outdoor air for free cooling when conditions allow, carry MERV 14 final filters, and measure their own outdoor airflow and the carbon dioxide in the air they return. New ductwork is sloped to shed water and aluminum-jacketed to match what was already on the roof, and the piping to the coils is heat-traced for the coldest nights. The units report to new Automated Logic controls, with graphics, alarms and trending in WebCTRL for the district's maintenance staff.

What the district has now is a fine arts wing with new equipment on a new roof, set up so that the next roof replacement does not start with a crane. For a district with rooftop air handlers and a roof both getting close to their dates, the lesson is to look at them as one project: the crane, the curbs and the sequence are shared, and so is the opportunity to fix how the equipment sits on the building.

Daikin air handler on its steel platform beside an aluminum-jacketed duct riser on the new Hamilton High School roof

Two Daikin air handlers joined by insulated ductwork on the north wing roof, with an arched-roof building in the background

New white TPO roof with yellow-edged walkway pads along the brick wall and windows of the Hamilton High School fine arts wing

Technical Discussion

Why the new air handlers stand on steel instead of the old curbs

The default when a rooftop unit is replaced is to set the new one where the old one was, on the existing curb or on a curb adapter. The ductwork below stays put, the roof opening stays put, and the structural question never comes up. At Hamilton High School's north wing that default stopped working the moment the new units were selected.

The new unit did not fit the old support

The two new Daikin air handlers are smaller and lighter than the units they replaced. Each one is about 162 by 70.5 inches and weighs 3,048 pounds. The old curbs had been framed around the old units and the steel angles that carried them, and the new units' base rails no longer landed on that support. A curb adapter could have bridged the difference in outline, but it would still have put the weight where the old framing was, not where the new unit's rails are.

The deck is not the structure

Under the membrane, this wing's roof is poured gypsum on bulb tees. That deck spans between the steel and carries roof loads; it is not something to set a concentrated load on. Spread over its footprint, a 3,048-pound unit works out to roughly 38 pounds per square foot, but it does not bear evenly. It bears on its base rails, and the rails have to land on steel.

So the structural engineer designed a new steel platform, about two feet tall, that sits on the existing W16 beams, which run at about eight feet on center. The legs pass through the roof and are flashed; the air handlers sit on the platform; the platform takes the load straight to the beams.

Two side-by-side roof sections. Left, labeled reuse the old curb: a dashed smaller new unit sits on an old curb over a gypsum deck and misses the old support angles. Right, labeled new steel platform as built: a 3,048-pound Daikin air handler on a steel frame about two feet above the roof, its flashed legs passing through the new TPO to existing W16 beams about eight feet on center. — The new units' weight goes to the building's W16 beams on a steel platform, and the new TPO roof runs continuously underneath.

What the platform buys besides structure

A unit on a curb interrupts the roof: the membrane runs up the curb, is flashed at its top, and is trapped under the unit until the unit is lifted off. A unit on a two-foot platform leaves the roof continuous beneath it, broken only at the legs. On this project that meant the new 80-mil TPO went down under the equipment in one piece with the rest of the section, and the next roofer can inspect, repair or replace it without a crane. It also let the crew take out 18 abandoned curbs on the wing and fill the deck, so the new roof carries no penetrations that serve nothing.

The question to ask when rooftop equipment is replaced is not whether the old curb is still there. It is where the new unit's weight will land, and what the answer does to the roof the unit is standing on.

Our Work