What the Baton Rouge/Ryan Field station records
NOAA's engineering weather data places its Baton Rouge/Ryan Field station at an elevation of 69 feet. For that station it gives a 1% summer design temperature of 92°F, with a mean coincident wet-bulb temperature of 77°F, and a 99% winter design temperature of 30°F. At Baton Rouge/Ryan Field, NOAA also counts about 2,213 hours in an average year when the wet-bulb temperature is above 73°F, and about 3,994 hours when it is above 67°F. The same Baton Rouge/Ryan Field data lists a 50-year basic wind speed of 120 mph (3-second gust at 33 feet), a 100-year rainfall rate of 4.0 inches per hour and about 14 freeze-thaw cycles in an average year.
Those are the station's numbers. Everything else on this page concerns your own house in East Baton Rouge Parish: its rooms, its ductwork, its windows and the way your household uses it. The sections below follow the order in which a careful contractor tends to work through a replacement.
One machine, two jobs
A central air conditioner changes the air in two ways at once. It lowers the temperature, and it pulls water vapor out, which condenses on the indoor coil and drains away. Trade people call these sensible and latent capacity. Equipment that drops the temperature fast and then shuts off can leave a room cool but clammy, because the coil never ran long enough to wring much water out.
Questions that get at the moisture side of a bid:
- What sensible and latent capacity does the matched outdoor and indoor pair have, according to the manufacturer's performance data?
- Would a two-stage or variable-speed system, or a slower blower setting, give the house longer and steadier run times?
- Is a separate whole-house dehumidifier worth discussing for this house, and where would it drain?
- Can the thermostat display indoor humidity, and where will it be mounted?
Ask for the load calculation in writing
The size of a new system should come out of arithmetic, not out of the sticker on the old one. A room-by-room load calculation (usually called a Manual J) adds up heat gained and lost through each wall, window, ceiling and duct run. Ask each bidder:
- Will you run that calculation for this house and leave me a copy?
- Which outdoor design values went into it, and where did they come from?
- Did you measure the insulation, window sizes and air leakage, or assume them?
- What capacity does the result call for, and how does it compare with what is installed now?
If two bids propose very different sizes, put the two calculations next to each other and ask each contractor to explain the gap.
The federal floor for new split systems
The Department of Energy puts Louisiana in its hot-humid Southeast region. There, split-system central air conditioners installed on or after January 1, 2023 must be rated at least 14.3 SEER2 (13.8 SEER2 for 45,000 Btu/h and larger); split-system heat pumps must meet 14.3 SEER2 and 7.5 HSPF2 nationwide.
A rating belongs to a combination, not to a single box. Ask that every SEER2 or HSPF2 figure in a bid refer to the exact outdoor unit paired with the exact coil or air handler being quoted, and ask for the AHRI reference number for that pairing so you can look it up yourself.
Where the coil's water goes
All the water an air conditioner removes has to leave the house. On a system with the air handler in an attic or closet, ask:
- Where does the primary condensate line run, and where does it end outdoors?
- Is there a secondary drain pan under the unit, and a float switch that shuts the system down if water backs up?
- Does the line have a trap and a cleanout, and how should it be flushed?
- If a pump lifts the water, how loud is it and what happens when it fails?
A clogged line that overflows into a ceiling is a nuisance a few cheap parts can prevent.
Ducts and the air coming back
New equipment cannot fix a leaky duct system. Ducts that run through an attic lose cooling through gaps at joints and boots, and a return that is too small makes the blower work against high pressure, which tends to be noisy. Ask whether the bid includes a duct leakage test and a static pressure reading, which joints would be sealed, whether any ducts would be replaced or re-insulated, and whether more return air is needed for the new blower.
Heating: heat pump, furnace or both
For the heating side, bids generally offer a heat pump with electric backup strips, a gas furnace paired with an air conditioner, or a dual-fuel setup that uses both. Ask why the contractor favors one, at what outdoor temperature the backup heat would turn on, and what each option might cost to run per year at your actual gas and electric rates. Ask to see the calculation behind that estimate.
Before you sign
Search for the company on LSLBC's license search, and put these to each bidder:
- What state license, if any, covers this work, and what is the number?
- Which permits does the job need, and who pulls them?
- Will your own employees do the installation, or a subcontractor?
- Can you show proof of liability coverage and workers' compensation?
- How will the refrigerant in the old equipment be recovered?
- After start-up, will you record airflow, refrigerant charge and the temperature drop across the coil, and give me a copy?
Weighing the bids
Line the proposals up on the same items: model numbers for both the outdoor and indoor units, the matched SEER2 and HSPF2, the load calculation and the size it supports, backup heat, duct testing and repairs, drain and float switch work, thermostat, removal of the old system, permits, start-up checks, and the parts and labor warranty terms in writing. When a bid skips an item, ask about it before comparing totals.