Montgomery/Dannelly Field in NOAA's design tables
NOAA's engineering weather data lists a station named Montgomery/Dannelly Field, at an elevation of 203 feet. For that station, NOAA gives a 1% summer design temperature of 93°F with a mean coincident wet-bulb temperature of 76°F, and a 99% winter design temperature of 27°F.
The federal efficiency floor in Alabama
The Department of Energy places Alabama in its hot-humid Southeast region. In that region, 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.
Reading the rating on a matched pair
A split system is two halves: an outdoor condenser or heat pump, and an indoor coil sitting on a furnace or inside an air handler. The published efficiency rating belongs to the combination, not to either cabinet on its own, so the model number on the outdoor unit tells only part of the story. For every option a contractor puts in front of you, ask:
- What are the exact model numbers of the outdoor unit, the indoor coil and the furnace or air handler?
- What is the AHRI reference number for that exact combination, and which SEER2 rating, plus HSPF2 for a heat pump, does that listing show?
- If the plan keeps your existing indoor coil or furnace, which rating applies to the pair as it will really be installed?
- Will the ratings appear in writing on the proposal, beside the model numbers?
Ask for a printout of the AHRI listing with each proposal. It turns a sales claim into a line you can look up yourself.
A week of noticing before anyone visits
An estimator sees your house during one visit; you live in it every day. In the week before the first appointment, jot down what you notice:
- which rooms run warm on summer afternoons, and which feel chilly on winter mornings;
- whether the air indoors ever feels damp or sticky while the thermostat says it is satisfied;
- how long the system runs once it starts, and whether it switches on and off in quick bursts;
- any water in the drain pan, on the floor beside the air handler, or a stain on the ceiling below it;
- the filter size, and how fast a fresh filter turns gray;
- your last year of power and gas bills, if you are willing to share them.
Hand the notes over at the start of the visit. They give the estimator something concrete to check, and they make it easier to see afterward which bidder paid attention.
Sizing, asked plainly
Capacity is hard to change once the equipment is set. Put the same questions to every bidder:
- Was the size worked out room by room, with a load calculation such as a Manual J, and will a copy of the report come with the proposal?
- Which outdoor design conditions went into that calculation, and from what source?
- Were window areas, insulation levels and duct runs measured, or assumed?
- How close does the proposed capacity sit to the calculated load, and why that size rather than the next size down?
If a contractor proposes the same size as the old unit without running numbers, ask what that choice rests on.
Moisture removal belongs in the bid
At the indoor coil, an air conditioner does two jobs at once: it cools the air and it wrings water out of it. Equipment that drops the temperature quickly and then shuts off can leave the second job unfinished. Ask how each option deals with indoor humidity:
- Is the compressor single-stage, two-stage or variable-speed, and how does that change the length of each run?
- Which blower setting do you recommend for summer, and why?
- Can the proposed thermostat or control read and display indoor humidity?
- Would a dedicated dehumidifier suit this house, and if so, where would it drain and how would it be powered?
Heat pump or gas heat
The heating side deserves its own comparison. Ask each contractor to quote every arrangement they are willing to install, on one sheet:
- Heat pump with electric backup. Request the maker's published heating output at low outdoor temperatures for the exact model, the size of the backup strips, and what brings them on.
- Gas furnace and central air conditioner. Request the furnace's AFUE rating, how and where it will vent, and whether the burner fires in one stage, two stages or modulates.
- Heat pump paired with a gas furnace. Ask at what outdoor temperature the system hands off from one to the other, who chooses that point, and whether you can adjust it later.
Then ask to see how each option's yearly operating cost was estimated, using the rates printed on your own bills.
Where the air handler and its drain sit
Wherever the indoor unit lives, whether a hall closet, a garage or an attic, it produces water through the cooling months. Ask:
- Where does the condensate line run, and where does it end outside or at a drain?
- Is there a secondary pan, or a float switch that shuts the system down before water overflows?
- If the unit sits in an attic, how will the platform, the ducts and their connections be sealed and insulated?
- How much room will a technician have later to slide out the filter and reach the coil?
Paperwork and coverage
Before you sign, ask the contractor:
- What state license or registration, if any, covers this work, and what is the number?
- Which permits does this installation need, who pulls them, and will an inspector come to the house?
- Will you hand over proof of liability coverage and workers' compensation before work starts?
- Who registers the equipment warranty, and what upkeep does it require to stay valid?
- How will the refrigerant in the old equipment be recovered?
What to hold each bid to
Proposals only compare fairly once each answers the same list. Lay them out together and check that every one names the model numbers and AHRI reference, the load calculation, the humidity approach, the heating arrangement and its controls, venting for any gas appliance, duct repairs or sealing as a separate line, the thermostat, removal of the old equipment, permits, start-up readings, and parts and labor warranties in writing. Anything left blank is a question to send back to that contractor before you choose.