HVAC Installation Inspection

Per IMC Section 301.1, HVAC equipment must be sized to maintain design conditions based on the building's calculated heating and cooling loads. ACCA Manual J establishes the methodology for residential load calculations, and ACCA Manual S governs equipment selection to match those loads. Equipment must be installed with manufacturer-specified clearances and per IMC Section 304 for access and working space — a minimum 30" × 30" service access panel or opening is required. Equipment must be listed and labeled per IMC Section 301.3.

1. Verify load calculation report (ACCA Manual J) matches installed equipment capacity — equipment should not exceed 115% of the calculated cooling load per Manual S

2. Confirm equipment nameplate data matches mechanical plan specifications and permits

3. Measure clearances around equipment against manufacturer installation instructions and IMC Section 304 access requirements

4. Check that equipment is level, securely mounted, and has vibration isolation where required

5. Verify condensate drain routing per IMC Section 307.2 — drain must be trapped and routed to approved disposal point

6. Confirm equipment has a disconnect switch within sight per NEC 440.14

- Oversized equipment causing short cycling, poor humidity control, and higher energy use

- Load calculation not performed or based on outdated square-footage rules of thumb instead of Manual J

- Insufficient service clearance preventing maintenance access

- Missing or improperly routed condensate drain lines

- Equipment not level, causing drainage and operational issues

Per IRC M1601, ducts must be constructed of approved materials and installed per SMACNA (Sheet Metal and Air Conditioning Contractors' National Association) standards. Duct sizing must follow ACCA Manual D to deliver proper airflow to each room. Joints and seams must be mechanically fastened and sealed with mastic or UL 181-rated tape per IRC M1601.4.1. Ducts in unconditioned spaces must be insulated to a minimum R-8 per IECC Section R403.3.1. Flexible duct must be supported at intervals not exceeding 5 feet and must not sag more than 1/2 inch per foot per IRC M1601.4.3.

1. Verify duct sizes match ACCA Manual D calculations or mechanical plans at each branch and trunk

2. Inspect all joints and connections for mechanical fasteners and proper sealing with mastic or UL 181-listed tape

3. Confirm duct insulation R-value meets IECC requirements — R-8 minimum for ducts in unconditioned spaces

4. Check flexible duct for proper support (maximum 5-foot intervals), minimal excess length, and no kinks or sharp bends

5. Verify return air pathways are adequate — transfer grilles or jump ducts installed where doors isolate rooms

- Undersized ducts creating excessive static pressure and reduced airflow

- Unsealed joints causing significant duct leakage (typical leakage rates of 25-40% in poorly sealed systems)

- Excessive use of flexible duct with kinks, sags, or unnecessary length adding resistance

- Missing or compressed insulation on ducts in unconditioned attics or crawl spaces

- Inadequate return air paths causing pressure imbalances between rooms

Per IMC Chapter 11 (Refrigeration), refrigerant piping must be installed using approved materials (typically ACR copper tubing) with brazed joints for systems exceeding 20 psig. Line sizes must match manufacturer specifications for the installed line-set length. Suction lines must be insulated with minimum 3/4" wall closed-cell insulation per IMC Section 1105.5. All technicians handling refrigerants must hold EPA Section 608 certification. Refrigerant charge must match manufacturer specifications and be verified by superheat or subcooling method.

1. Verify refrigerant line sizes (liquid and suction) match manufacturer specifications for the total line-set length and elevation change

2. Inspect suction line insulation — must be continuous, properly sealed at joints, and minimum 3/4" wall thickness

3. Confirm lines are properly supported with approved hangers at manufacturer-specified intervals and protected from physical damage

4. Check that brazed joints are clean with no visible flux residue or evidence of overheating

5. Verify installer holds current EPA Section 608 certification (Universal or Type II minimum for residential split systems)

- Incorrect line sizes causing poor system performance, excessive superheat, or oil return issues

- Missing or damaged suction line insulation leading to condensation and capacity loss

- Refrigerant lines in contact with dissimilar metals without proper isolation causing galvanic corrosion

- Improper brazing technique introducing contaminants or causing leaks at joints

- Refrigerant charge not verified — either overcharged or undercharged from factory pre-charge without adjustment for line length

Per ASHRAE Standard 62.2, dwelling units must have whole-building mechanical ventilation providing continuous airflow calculated as 0.03 CFM per square foot of floor area plus 7.5 CFM per bedroom plus one. Local exhaust is required in kitchens (100 CFM intermittent or 25 CFM continuous per ASHRAE 62.2 Section 5.2) and bathrooms (50 CFM intermittent or 20 CFM continuous). IMC Chapter 4 governs ventilation air requirements for mechanical systems. Outdoor air intakes must be located per IMC Section 401.5 — minimum 10 feet from contamination sources.

1. Verify whole-building ventilation rate matches ASHRAE 62.2 calculation for the dwelling's floor area and bedroom count

2. Measure kitchen exhaust fan airflow — minimum 100 CFM intermittent or 25 CFM continuous

3. Measure bathroom exhaust fan airflow — minimum 50 CFM intermittent or 20 CFM continuous per ASHRAE 62.2

4. Check outdoor air intake location — minimum 10 feet from exhaust outlets, plumbing vents, and other contamination sources per IMC Section 401.5

5. Verify exhaust ducts are properly routed to the exterior — not terminated in attics, crawl spaces, or soffits per IRC M1501.1

- No whole-building ventilation system installed despite tight building envelope

- Bathroom exhaust fans venting into attic spaces instead of to the exterior

- Outdoor air intake located too close to exhaust outlets or garage openings

- Kitchen range hood not ducted to exterior (recirculating hoods do not meet code for required exhaust)

- Inadequate makeup air for large kitchen exhaust fans exceeding 400 CFM per IMC Section 505.2

Per IRC G2407 (IMC Section 701), fuel-burning appliances must receive adequate combustion air through properly sized openings or ductwork. For confined spaces, two permanent openings are required — one within 12" of the ceiling and one within 12" of the floor, each sized at 1 square inch per 1,000 BTU/hr input for outside air (IRC G2407.6). Venting of combustion products must comply with IRC G2427 (IMC Chapter 8). Category I appliances require Type B vent or masonry chimney with proper clearances. High-efficiency condensing appliances (Category IV) require PVC or CPVC venting per manufacturer specifications.

1. Verify combustion air openings are properly sized per IRC G2407 — calculate total BTU input of all appliances in the space

2. Check that combustion air pathways are unobstructed and openings have not been blocked or reduced

3. Inspect vent connector pitch — minimum 1/4" per foot upward slope toward chimney for Category I appliances per IRC G2427.10.5

4. Verify vent termination clearances from windows, doors, and air intakes per IRC G2427.8 — minimum 4 feet below, 4 feet horizontally, or 1 foot above any opening

5. For condensing appliances, confirm PVC/CPVC vent pipe is properly supported, sloped back to appliance for condensate drainage, and uses correct solvent cement

- Combustion air openings blocked or sealed during finishing work

- Undersized venting causing backdrafting and potential carbon monoxide exposure

- Single-wall vent connector used where double-wall (Type B) is required due to clearance to combustibles

- Improper vent termination location near operable windows or fresh air intakes

- Missing condensate drain trap on condensing furnace vent system

Per IRC M1401.3, every heating and cooling system must have an accessible thermostat or control device. IECC Section R403.1.1 requires programmable thermostats capable of maintaining different setpoints for at least two periods within 24 hours. Thermostats must be installed approximately 5 feet above the floor on an interior wall, away from direct sunlight, supply registers, and heat sources per manufacturer instructions. ENERGY STAR certified thermostats (including smart thermostats) meet efficiency criteria established by EPA. Safety controls including high-limit switches, fan controls, and refrigerant pressure switches must be factory-installed and operational per IMC Section 1006.

1. Verify thermostat is located on an interior wall at approximately 5 feet above floor level, away from supply registers, windows, and direct sunlight

2. Confirm thermostat is programmable or smart type meeting IECC Section R403.1.1 requirements

3. Test heating and cooling mode operation — system responds correctly to setpoint changes within manufacturer-specified time

4. Verify safety controls are operational — high-limit switch, fan delay, and low-voltage transformer are properly wired

5. Check that multi-zone systems have individual thermostats per zone with proper damper control wiring

- Thermostat placed on exterior wall or near heat sources causing inaccurate temperature readings

- Non-programmable thermostat installed where energy code requires programmable capability

- Incorrect thermostat wiring causing improper staging or fan operation

- Missing C-wire (common wire) for smart thermostat installation causing intermittent power issues

- Zone dampers not properly calibrated or wired to corresponding thermostats

Per ACCA Standard 5 (Quality Installation Specification), installed HVAC systems must be tested and verified for proper operation before occupancy. Total external static pressure must not exceed manufacturer-rated maximum (typically 0.50" w.c. for residential systems). Airflow must be verified at 350-400 CFM per ton of cooling capacity. Duct leakage testing per ASHRAE Standard 152 or IECC Section R403.3.5 requires total duct leakage not to exceed 4 CFM25 per 100 square feet of conditioned floor area. Temperature differential across the evaporator coil should measure 14-22°F in cooling mode.

1. Measure total external static pressure with a manometer at supply and return plenums — must not exceed equipment manufacturer's maximum rated ESP

2. Verify airflow per room with an anemometer or flow hood — total system airflow should be 350-400 CFM per ton of cooling

3. Perform duct leakage test per IECC Section R403.3.5 — maximum 4 CFM25 per 100 sq ft of conditioned floor area

4. Measure supply and return air temperatures — cooling mode temperature split should be 14-22°F across the evaporator coil

5. Verify refrigerant charge using superheat method (fixed metering) or subcooling method (TXV) per manufacturer specifications

6. Test all safety controls — high-limit switch, pressure switches, and flame safeguard operate correctly

- Excessive static pressure from undersized ducts or dirty filters restricting airflow

- Airflow significantly below 350 CFM per ton causing frozen coils and poor dehumidification

- Duct leakage exceeding code limits due to unsealed connections at boots, plenums, or branch takeoffs

- Refrigerant charge incorrect — not adjusted for actual line-set length versus factory pre-charge assumptions

- Commissioning documentation not provided to homeowner including equipment data, test results, and warranty information