AC Installation in Kirkwood and West St. Louis County

An AC installation in Climate Zone 4A is not an equipment-swap exercise. It’s a load calculation, an equipment match, and a duct verification — performed in that order, before any condenser model number is selected. The Manual J load calculation determines the required cooling capacity in BTU/hr; the Manual S equipment selection matches AHRI-rated equipment within 0–15% of that calculated load; the Manual D duct verification confirms the existing ductwork can handle the new equipment’s blower at the design friction rate. If any step is skipped or shortcut, the installed system will short-cycle through summer, leave indoor relative humidity at 65%, and reduce equipment service life by 30–40%. Kirkwood, Webster Groves, Crestwood, Affton, Sappington, and Town and Country homeowners deserve installations done with the engineering rigor the equipment manufacturer assumes during the warranty period.

Step 1: Manual J Load Calculation

The ACCA Manual J load calculation uses Wrightsoft Right-J software with the specific climate data for St. Louis Lambert (ASHRAE 99% winter design 3°F, 1% summer design 94°F dry bulb / 76°F coincident wet bulb, Climate Zone 4A) and the specific characteristics of your home:

• Square footage by floor with ceiling heights documented
• Window U-factors and SHGC (Solar Heat Gain Coefficient) values, with orientation noted for each window
• Wall, ceiling, and floor insulation R-values
• Air infiltration rate (measured via blower door if available, or estimated from construction era and tightness category)
• Internal heat gains: occupants (sensible and latent loads), lighting, appliances, electronics
• Duct gains and losses if ductwork runs through unconditioned space (attic, crawlspace, garage)

The Manual J output gives total cooling load in BTU/hr, split into sensible (temperature reduction) and latent (humidity removal) components. For a typical 2,400-square-foot Kirkwood home built in the 1970s, this typically calculates to 28,000–36,000 BTU/hr total cooling load with 70/30 sensible-to-latent split — matching a 2.5–3 ton AHRI-rated condenser, depending on the specific home characteristics.

Step 2: Manual S Equipment Selection

Manual S equipment selection matches AHRI-rated equipment to the calculated cooling load. The selection considers:

• Total cooling capacity at design conditions. Equipment within 0–15% of the Manual J calculated total load.
• Sensible-to-latent capacity ratio at the 76°F design wet bulb. Equipment with too high a sensible heat ratio will short-cycle in mixed-humid conditions; equipment matched to the calculated 70/30 split provides proper dehumidification.
• Heating capacity match for heat pump configurations. Cooling and heating loads typically don’t match exactly in Climate Zone 4A — the equipment selection prioritizes cooling sizing accuracy while ensuring heating capacity meets the 3°F design load with reasonable auxiliary backup.
• R-454B refrigerant compatibility. All AIM Act compliant residential equipment installed in 2025 and forward uses R-454B (GWP 466) or R-32 (GWP 675). Carrier, Trane, Lennox, Bryant, Rheem, Goodman, Mitsubishi, Daikin, and Bosch all have R-454B compliant residential lines.
• SEER2 efficiency rating. Federal minimum is 14.3 SEER2 in the Southeast region (Missouri is included). Equipment ranges from 14.3 SEER2 (entry-level single-stage) through 26 SEER2 (top-tier variable-capacity inverter-driven).
• Manufacturer ecosystem. Communicating thermostats and indoor units are matched to specific outdoor units in the same brand series.
• Utility rebate qualification. Ameren Missouri offers heat pump rebates that apply only to equipment meeting specific SEER2/HSPF/COP at low temperature thresholds.

Step 3: Manual D Duct Verification

If existing ductwork is staying (which is typical on residential replacement installs), Manual D verification confirms the new equipment’s blower capacity can move the design CFM through the existing duct system without exceeding the design friction rate (typically 0.05–0.08 inches WC per 100 feet of equivalent length).

Measurements include trunk and branch dimensions, calculated equivalent length including elbows and takeoffs, and verification of the design friction rate against the proposed equipment’s blower performance. If the existing ductwork is undersized for the new equipment’s blower capacity, options include modifying ductwork to handle the higher CFM, selecting equipment with a higher static pressure capacity blower, or downsizing the equipment if the original ductwork was sized for a smaller system.

This step is the one most often skipped in residential AC installations. Equipment installed on undersized ductwork operates at elevated static pressure, reducing airflow across the evaporator coil, causing the coil to run colder than design (potentially freezing in mild weather), reducing dehumidification capacity, increasing blower energy consumption, and accelerating motor wear.

Step 4: Written Quote

The written installation quote itemizes:

• Equipment cost: matched outdoor condenser, indoor coil, blower or air handler if replacing, with model numbers
• Labor hours at our standard installation rate
• Permit fees at cost through Kirkwood Public Works, St. Louis County DPW, Webster Groves PW, Crestwood PW, or Town and Country PW depending on jurisdiction
• Refrigerant by the pound (R-454B charging weight specified by manufacturer)
• Electrical work: disconnect upgrade, breaker resize, conduit modification, whip replacement
• Venting modifications if a furnace and condenser are being replaced together (sidewall PVC venting for condensing furnaces, masonry chimney liner if required for non-condensing replacement)
• Pad or platform: composite condenser pad, leveling, vibration isolation
• Manufacturer warranty registration (typically free, included in install scope)
• Purisync 2-year labor warranty (included)
• Extended labor warranty options: 5, 10, or 12 years through manufacturer-backed programs (priced separately)
• Total all-in price

Quotes are valid for 30 days. No “this price is only good if you sign today” pressure. No verbal estimates. No package pricing that hides margin allocation.

Installation Day Sequence

A typical residential AC replacement is a one-day install, beginning at 8:00 AM and completing by mid-afternoon. Specific sequence:

1. Floor protection and walkthrough. Canvas drop cloths from entry to work area, plastic sheeting where evaporator coil removal will generate condensation runoff, shoe covers on every technician.
2. Refrigerant recovery. Refrigerant is recovered from the existing system per EPA Section 608 requirements using Type II certified recovery equipment, with recovery cylinder weights documented before and after to verify recovery completeness.
3. Outdoor unit removal. Disconnect electrical, disconnect refrigerant line set at the service valves, lift the condenser off the existing pad. Old equipment goes to a licensed reclaimer with chain-of-custody documentation.
4. Indoor coil removal. Disconnect refrigerant line set at the coil, disconnect condensate drain line, remove the existing evaporator coil from the air handler or furnace cabinet.
5. Line set evaluation. Existing refrigerant line set is inspected for usability with the new equipment. R-454B line sets typically require different sizing than legacy R-22 systems but match R-410A line sets in most residential configurations. New line set is installed if existing is incompatible, damaged, or undersized.
6. New equipment placement. Composite pad placement with leveling verification, condenser placement, electrical disconnect installation, line set connection with flare nut torque verification (or braze if specified by manufacturer).
7. Indoor coil installation. New evaporator coil placement in the air handler or furnace cabinet, condensate drain line connection, secondary drain pan installation if required by code.
8. System pressure test. Nitrogen pressure test to manufacturer-specified pressure to verify joint integrity. Pressure decay test of 10–15 minutes confirms no leaks.
9. Vacuum pull. Vacuum pull to 500 microns or below, held for the manufacturer-specified duration to verify system dehydration and joint integrity.
10. Refrigerant charge. Charge to manufacturer specification by weight using a charging cylinder on a scale. Final adjustment by subcooling (TXV-equipped systems, target 7–10°F at AHRI rating conditions) or superheat (piston-equipped systems).
11. Electrical verification. Voltage verification at the disconnect, amperage verification at the compressor and condenser fan motor, capacitor microfarad verification.
12. Commissioning. Static pressure measurement across the air handler (target under 0.5" WC standard, under 0.8" WC for ECM variable-speed), supply and return temperatures, supply CFM verification, refrigerant pressures at operating conditions.
13. Customer walkthrough. New thermostat operation, filter location and MERV rating, recommended filter change interval, location of emergency electrical disconnect, manufacturer warranty paperwork, Purisync labor warranty card.

Permits and Inspection

Installation permits are pulled through the applicable municipal authority within one business day of contract signing:

• Kirkwood Public Works — 139 S Kirkwood Rd, Kirkwood, MO 63122. (314) 822-5800.
• St. Louis County Department of Public Works — 41 S Central Ave, Clayton, MO 63105. (314) 615-8530. (Covers Affton and Sappington.)
• Webster Groves Public Works — 4 E Lockwood Ave, Webster Groves, MO 63119. (314) 963-5300.
• Crestwood Public Works — 1 Detjen Dr, Crestwood, MO 63126. (314) 729-4790.
• Town and Country Public Works — 1011 Municipal Center Dr, Town and Country, MO 63131. (314) 432-6606.

Municipal inspector visits within 5–10 business days of installation completion. We coordinate the inspection time with you and meet the inspector on site if requested.

Manufacturer Warranty Registration

Tess submits manufacturer warranty registration within the 60- to 90-day window required by Carrier, Trane, Lennox, Bryant, Rheem, Goodman, Mitsubishi, Daikin, and Bosch. The manufacturer confirmation email is forwarded to you for your records. Failure to register within the window typically reduces coverage to the manufacturer default (5 years parts) — we register on every install as part of the install scope.

Frequently Asked Questions

What does an AC installation cost in Kirkwood?

Pricing varies by equipment tier, capacity, and installation scope. A typical 3-ton single-stage R-454B condenser with matched evaporator coil and standard installation runs $5,800–$8,400 all-in including permit. Two-stage 3-ton equipment runs $7,200–$10,800. Variable-capacity inverter-driven equipment (Carrier Infinity, Trane XV20i, Lennox Signature Collection, Mitsubishi Hyper-Heat) runs $10,400–$16,500. Pricing depends on equipment selection, electrical or venting modifications required, ductwork modifications, and whether a furnace or air handler is being replaced concurrently. Written quotes itemize every line item — no package pricing that hides allocation.

How long does an AC installation take?

A typical residential AC condenser and evaporator coil replacement is a one-day install, starting at 8:00 AM and completing by mid-afternoon. Complete HVAC system replacement (furnace, condenser, evaporator coil, line set, possibly ductwork modifications) typically runs 1.5–2 days. Ductless mini-split installation with 2–4 indoor heads typically runs 2–3 days. Pre-install equipment delivery and permit pull typically takes 5–10 business days from contract signing.

Do I need new ductwork with a new AC?

Not usually. Existing ductwork is verified during the Manual D step of our installation process — measurements include trunk and branch dimensions, calculated equivalent length, and verification of design friction rate against the proposed equipment’s blower performance. If existing ductwork can handle the new equipment’s blower at design friction rate (typically 0.05–0.08 inches WC per 100 feet of equivalent length), it stays. If undersized or damaged, options include duct modifications, equipment selection with higher static pressure capacity blower, or downsizing the equipment. Most residential replacements in Kirkwood, Webster Groves, and Crestwood retain existing ductwork.

What’s the AC warranty on a new Purisync install?

Manufacturer parts warranty typically 10 years on parts and 10 years on compressor for residential equipment from Carrier, Trane, Lennox, Bryant, Rheem, Goodman, Mitsubishi, Daikin, and Bosch (registered within the 60- to 90-day window required by the manufacturer). Purisync provides a 2-year labor warranty on every new installation. Extended labor coverage (5, 10, or 12 years) is available at the time of install through manufacturer-backed extended warranty programs at additional cost. Full warranty details at /warranty/.

Why does Purisync use ACCA Manual J instead of square-footage sizing?

Square-footage rules of thumb (“500 square feet per ton”) ignore the actual factors that drive cooling load: window orientation and U-factor, insulation R-values, infiltration rate, internal heat gains, duct losses, and the climate-specific design conditions (Climate Zone 4A, 94°F dry bulb / 76°F wet bulb at St. Louis Lambert). Equipment sized by square footage alone is typically oversized by 20–40%, which causes short cycling, poor dehumidification, accelerated equipment wear, and 65% indoor relative humidity in summer. Manual J using Wrightsoft Right-J software with actual ASHRAE design data sizes equipment to the actual calculated load, producing the comfort and efficiency outcomes the equipment manufacturer’s SEER2 rating assumes.

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Contact Purisync Heating and Air

For AC installation quotes, equipment recommendations, or Manual J load calculation consultation, contact our 325 N Kirkwood Road office. Installation scheduling typically targets 5–10 business days from contract signing, with emergency same-day replacement available during Polar Vortex weeks or summer heatwaves when equipment can be pulled from distributor inventory inside 4 hours.

• Emergency Line (24/7): (314) 338-5111
• Address: 325 N Kirkwood Rd #245, Kirkwood, MO 63122
• Email: info@purisyncheatingairconditioning.xyz
• St. Louis County Mechanical Contractor License: #MC-2014-08439-STL
• Kirkwood Business Registration: #BL-2014-1187
• EPA Section 608 Universal: #608U-2014-385721

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Office Hours

• Emergency Service: 24 hours a day, 7 days a week
• Office Staff: Monday – Saturday, 9:00 AM – 5:00 PM
• Closed: Sundays and State/Federal Holidays (emergency line always active)