The air handler in a Murray Hill closet, and the February pollen it has to swallow

Late February on Edgewood Avenue

The oaks let go in the last week of February. For the next ten or twelve weeks, cars along Edgewood Avenue wear a yellow-green coat, and so does every return grille in Murray Hill.

Picture a 1,100-square-foot 1920s house a few blocks off the strip. The air handler lives in a hall closet behind a louvered door, where somebody put it in the 1990s when the house got central air. It is a vertical unit with a one-inch filter slot that has not seen a new filter since Thanksgiving. The blower motor has started a faint grinding note on startup, the coil is matted with pollen, and the owner notices that the bedroom at the back never quite cools.

That is the seasonal moment this page is about. Pollen plus a tired blower plus a starved return is the most common reason a Jacksonville air handler gets replaced in March.

What we would put in that closet

Our recommendation for that house, after a load calculation and a look at the return, is a variable-speed air handler sized to the condenser outside, with three changes to the closet itself:

1. A deeper filter cabinet. A four- or five-inch media filter in place of the one-inch slot. It holds a season of pollen without choking the blower, and it gets changed every few months instead of every few weeks.
2. A bigger return. The louvered door was never enough. We cut a proper return grille and, where the floor plan allows, add a second return near the back bedroom.
3. A float switch and a cleanable drain. Closets in these houses sit over heart-pine floors. A clogged condensate line in July should trip a switch, not stain the wood.

Electric heat strips go in sized for a Jacksonville winter: enough for the dozen freeze nights, no more. If the house is in a block that floods, the unit goes on a raised platform.

The swap, one Tuesday

An air handler replacement in a small house takes most of a working day.

• 8 a.m. Power off at the disconnect and the breaker. Refrigerant recovered from the old coil.
• Mid-morning. Old unit out through the hall, closet floor checked for rot, new platform or pad set.
• Midday. New air handler in, line set brazed and pressure-tested, drain run with a trap and a float switch, strips wired, filter cabinet mounted.
• Afternoon. Return opened up, supply plenum sealed with mastic, system evacuated and charged, blower speeds commissioned against the measured duct static pressure.
• Before we leave. Thermostat checked, filter shown, and the owner walked through the drain and the switch.

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Six months later

By late August the same house sits at a steady 75 degrees without the back bedroom lagging. The variable-speed blower runs low and long, which keeps the coil wet and the humidity in the low 50s rather than the high 60s. The media filter gets its second change of the year. The grinding note is gone, and so is the yellow film on the grille, because the filter is catching it before the coil does.

A Cook’s maintenance visit in the fall checks the blower amperage, the strips and the drain before the first freeze. Air handlers from Lennox are what we install; Carrier, Bryant, Trane and the rest are what we service across Jacksonville, from Murray Hill to the Beaches.