How we size a new system
We size every system with a Manual J load calculation, not a rule of thumb. Manual J is the industry method for working out how much heating and cooling a specific house actually needs.
It looks at your home's square footage, insulation, windows and which way they face, air leakage, ductwork location and Central Kentucky's weather. The result tells us the right capacity for your house, not the house down the street.
A lot of systems get sized by copying the old unit's tonnage or using "one ton per so many square feet." That skips everything that makes your house different, including any insulation, windows or additions you've changed since the last system went in.
Why a bigger system isn't better
An oversized AC cools the house too fast and shuts off before it's done its other job: pulling humidity out of the air. In a Kentucky summer, that leaves the house cool but clammy.
Oversizing also causes short cycling, where the system turns on and off every few minutes. That means more wear on the compressor, uneven temperatures from room to room, and a system that feels worse than its size suggests. An undersized system has the opposite problem and can't keep up on the hottest afternoons. Manual J gets it right.
What's included in an install
Every AC and heat pump install includes:
- Removal of your old equipment, with the refrigerant recovered properly
- A new pad for the outdoor unit
- Line set evaluation. If your refrigerant lines are the right size and in good condition, we clean, pressure-test and reuse them. If not, we replace them.
- Electrical connections, including the outdoor disconnect and wiring checks
- Thermostat installed or reconnected and set up for the new system
- Start-up testing, including setting the refrigerant charge, checking airflow and running the system through full cycles
- Permits. We pull permits where required.
- Clean-up before we leave
You'll get a firm quote that lists what's included before any work is scheduled.
The R-454B change and your new system
New residential AC and heat pump equipment made since 2025 uses A2L refrigerants, mainly R-454B or R-32, instead of R-410A. Nearly every new system on the market today uses one of them.
Two things matter for your install. First, the indoor coil and outdoor unit must be matched and rated for the same refrigerant, so a new outdoor unit almost always means a new indoor coil. Second, many A2L systems include a refrigerant leak sensor near the indoor coil. We check it during start-up.
Repair or replace: we quote both
If your system is older or facing a big repair, we'll give you repair and replacement quotes side by side. You see both numbers and decide.
Our usual guidance: under about 10 years old, repair is usually the better deal. Between 10 and 15, it depends on the repair and the system's condition. Past 15, or on a second major repair, replacement is worth pricing out.
Free second opinion on replacement quotes
Did another company tell you that you need a new AC, heat pump or furnace? Before you sign, call or text us. Our second opinion on a replacement quote is free. We'll come look at your system, go over that quote with you and tell you honestly whether a repair would do.
Sometimes it will. If it won't, we'll show you why and give you our own firm quote to compare. An existing R-410A system can still be repaired and serviced, so don't let the refrigerant change alone push you into a new system.
The free second opinion is for replacement quotes. When your heat or AC isn't working and you need a repair, the visit is our diagnostic: $39 when you mention our online special (regularly $79), credited in full to any repair you approve.
Most installs are done in one day
Most AC and heat pump installs are finished the same day we start. You'll have cooling or heat back that evening in most cases.
Some jobs take longer, like a tight crawlspace, ductwork changes or a system moving to a new location. If yours is one of them, we'll tell you when we quote it. That's the kind of work Sophia R. described:
“HVAC Doctor replaced my old system in the crawlspace, and they did an amazing job. The crew was on time, professional, and worked efficiently despite the tight space. They made sure everything was sealed properly and even cleaned up…”
AC Installation questions
How long does a new AC or heat pump installation take?
Most installs are done in one day. Jobs with extra work, like a hard-to-reach crawlspace, ductwork changes or moving equipment to a new spot, can take longer. We'll tell you the expected timeline when we quote the job, so you're not guessing about when your heat or cooling will be back.
Do you give free second opinions?
Yes, on replacement quotes. If another company told you that you need a new AC, heat pump or furnace, we'll come look at your system and go over that quote for free, and tell you honestly whether a repair would do. When something isn't working and you need a repair, the visit is our diagnostic: $39 when you mention our online special (regularly $79), credited in full to any repair you approve.
What size AC do I need?
We find out with a Manual J load calculation, which looks at your home's size, insulation, windows, air leakage and local weather. Copying the old unit's size is a common mistake, especially if you've added insulation or new windows. The right size keeps the house comfortable and pulls humidity out properly in a Kentucky summer.
Do I need to replace my indoor coil too?
Almost always, yes. New systems use A2L refrigerants like R-454B or R-32, and the indoor coil and outdoor unit have to be matched and rated for the same refrigerant. You can't pair a new A2L outdoor unit with an old R-410A coil. If your furnace is in good shape, it can often stay.
Can I still get an R-410A system?
Mostly no. Manufacturers switched new residential equipment to A2L refrigerants in 2025. A 2026 EPA rule change lets contractors install leftover R-410A equipment built before 2025, but that supply keeps shrinking. For most homeowners, a new A2L system makes more sense. Existing R-410A systems can still be repaired.
Which brands do you install?
We install all major brands. Rather than push one name, we recommend equipment that fits your house, your budget and how long you plan to stay. The Manual J calculation tells us the right size, and we'll explain the differences between the options we quote in plain language.
Are there rebates or tax credits for a new system?
The federal energy-efficiency tax credit for AC and heat pump equipment ended for systems installed after December 31, 2025, so we don't count on it in any quote. Check with Kentucky Utilities or your local utility for any current rebates. We'll share the equipment details you need to apply.
How much does a new AC or heat pump cost?
It depends on the size your home needs, the efficiency level you choose and what the install involves, like line sets, electrical or ductwork. We measure first, then give you a firm quote that spells out what's included. We don't post install prices because every house is different.
Where we work
Lexington and nine nearby towns, with no travel surcharge and the same flat-rate pricing everywhere.