Zoning a two-story in Cypress Landing, from the Tuesday call to the first evening the upstairs reads 74
The upstairs bedrooms in a 2006 two-story are six degrees warmer than the living room at bedtime. Here is what the week that fixes it looks like.
Tuesday, 6 p.m.: the call about the upstairs
Picture a mid-2000s two-story off Grandview Street in Cypress Landing. The thermostat downstairs says 74. The kids’ rooms upstairs, with the afternoon sun on the west wall and a July thunderstorm just passed, say 80. The homeowner has tried closing downstairs registers, which made the ducts whistle and did little else. She calls 866-266-5709 on Tuesday evening and the dispatcher books a visit for Wednesday.
This is the most common comfort complaint in Lake City’s 1990s and 2000s subdivisions, and it has a specific fix.
Wednesday: what changed in zoning since the house was built
When this house went up in 2006, zoning meant motorized dampers on a single-stage system and a bypass duct to dump the extra air when only one zone was calling. It worked, loudly, and it wasted energy. Three things have changed. Variable-speed equipment can now simply slow down when one zone closes, so the bypass is gone. Communicating controls let the thermostat, the blower and the dampers talk to each other instead of fighting. And the efficiency ratings moved to the SEER2 standard, which tests equipment against realistic duct resistance; a zoned system with partially closed dampers is exactly the condition that standard was written for, so the ratings on current equipment mean more for a zoned house than the old numbers did. The refrigerant transition matters here too: the current system is on a refrigerant still in production, which the 2006 unit is not.
On Wednesday the technician measures airflow to each floor, counts the returns, and confirms the existing air handler has a variable-speed blower that can take a zone controller. It does. The quote is for two zones, no new equipment.
What to buy now: variable-speed first, dampers second
If the equipment is being replaced anyway, the order is this. An indoor unit with a variable-speed blower and an outdoor unit that modulates, two-stage at minimum, because zoning without modulation is a compromise. A zone controller and one motorized damper per zone, installed in rigid trunk rather than flex. A thermostat or sensor per zone, placed away from the sunny wall and the supply register. And no bypass duct. If the equipment stays, as it did here, the same parts go on the existing system, and we are honest about the limits of a single-stage condenser if that is what is outside.
Ask whether your system can be zoned
Thursday: install day in the attic over Cypress Landing
The attic in July is the hardest part, so the crew starts early. The supply trunk is split where it already branches toward the stairs; a damper goes in each leg. The controller mounts to a truss near the air handler and is wired to the dampers, the equipment and the two sensors. The low-voltage wire to the upstairs sensor drops through a closet. The dampers are tested open and closed, the blower is set to modulate with zone demand, and airflow is checked at the upstairs registers with both zones calling and with each alone. The attic unit’s float switch gets looked at while someone is up there, because a ceiling under an attic air handler in a 54-inch rain year deserves it.
Thursday evening: the first reading
At 9 p.m., with the downstairs set to 74 and the upstairs set to 74, both floors read 74. The upstairs damper is open and the downstairs one mostly closed; the blower is loafing. The homeowner notices the quiet before she notices the temperature. Over the following week the FPL bill, which covers Cypress Landing inside the city, will show whether the system is running less overall; usually it does, because it stops overcooling the first floor to drag the second one down. The duct work is warranted, the controller carries its own parts warranty, and the fall maintenance visit will check the dampers before the heating season flips the problem on its head.
Dampers, controllers and the second floor
Does zoning require new equipment, or can it go on what I own?
It can be added to many existing systems, especially those with a variable-speed blower. On an older single-stage system it works with limits and a bypass arrangement we would rather avoid; if the equipment is near the end anyway, zoning goes in with the replacement.
How many zones does a two-story need?
Two is the common answer: upstairs and downstairs. A third zone for a bonus room above the garage or a master suite on its own side of the house is worth it when that room has its own schedule.
Will the downstairs get too cold when the upstairs is calling?
Not with a modulating system; it simply sends less air downstairs. That is the whole reason we pair zoning with variable-speed equipment rather than dumping excess air into a bypass.
What is the attic work going to disturb inside the house?
Very little. Dampers and the panel go in the attic; the only interior work is a small wall sensor or thermostat per zone and a low-voltage wire run, usually through a closet.
Second floor sweltering while the first floor shivers?
Call with the house's build year and floor count. Zoning may be a two-day fix.