When the August GRU bill says the package unit on the pad is done

What the bill is telling you

A GRU residential electric bill in August is the highest of the year for almost every household in Alachua County, so a high one by itself means little. The signal is the trend: this August against last August, with the same thermostat setting and the same people in the house. A package unit whose kilowatt-hours have climbed two summers running, while the house feels no cooler, is losing capacity. Dirty coils and low refrigerant charge explain some of it. A compressor working harder each year to do less explains the rest, and that one is not a tune-up.

Clay Electric and Duke customers in the rural county see the same pattern on different paper.

Who runs a package unit around Gainesville

A packaged system puts the compressor, both coils, the blower and the heat strips or gas section in one outdoor cabinet, connected to the house by a supply and a return duct through a wall or the floor. Around here that describes:

• Manufactured homes from Hawthorne and Waldo to Archer and the unincorporated stretches toward Micanopy.
• Site-built slab homes from the 1960s and 1970s in East Gainesville and the older Northwest streets, where there was never an attic platform or a closet.
• Student apartment complexes along SW 20th Avenue and Archer Road, where a dozen identical units sit in a row behind the buildings.
• Small commercial buildings with rooftop units: the strip centers, clinics and restaurants along Archer Road, Newberry Road and NW 13th Street.

Replacing a cabinet versus starting from a bare pad

Nearly all of our package work in Gainesville is retrofit. The new cabinet goes where the old one sat, which sounds simple and hides three decisions. First, whether the pad or roof curb is sound; a tilted pad on sandy soil west of I-75 strains the refrigerant lines and the duct connection. Second, whether the new unit’s footprint and duct openings match the old; adapters exist, and a well-built transition matters more than the box. Third, whether the electrical service is adequate, because many 1970s installs are on undersized wire and a disconnect that has been baking in the sun for forty years.

New construction is the exception, mostly commercial: a new building near the Progress District or a clinic off NW 39th Avenue where the engineer specified rooftop units, and we install to the drawings.

The ductwork underneath

A package unit can be no better than the duct it pushes into, and the duct on a Gainesville package job is often in the worst place a duct can be. Under a manufactured home it runs through a crawlspace that floods in a wet September, sags between supports, and splits at the boots where years of foot traffic above have worked the connections loose. In a 1960s slab house the trunk may be buried in the slab itself, and after heavy rain those ducts hold water and grow what you would expect. Under a rooftop unit, the supply plenum drops through a roof penetration that has moved with every reroof.

We pressure-test the duct before quoting a replacement. GRU’s residential duct test program is a reasonable paid alternative for homeowners who want an independent number first. Either way, no new cabinet overcomes a duct system leaking a third of its air into a crawlspace.

Sizing in a cabinet that comes in fixed steps

Package units come in half-ton steps, and the temptation is to match the nameplate on the old one. We run a load calculation instead, because the house has changed: windows replaced, insulation added or settled, a room enclosed, a tree grown over the roof. Oversizing a package unit is especially costly, since the whole machine cycles on and off outside and never logs enough run time to dry a house whose August dew point sits in the low 70s. Right-sized, a two-stage package unit holds a manufactured home drier at a higher thermostat setting, and that shows up on the next August bill in the direction you want. Inside GRU gas territory a gas-electric cabinet heats with a burner on the few dozen cold mornings; everywhere else, a heat pump package pays for itself on Clay Electric winter bills.