Install Quality Red Flags Reference

Why this matters

Most service calls are on equipment someone else installed. The install quality determines how the equipment performs, how long it lasts, and how frustrating it is to service. The tech who notices install red flags can flag them to the customer, plan around them, OR refuse work until they're addressed. This is the field card.

Why install quality matters more than equipment brand

Two same-model AC units, one installed well + one poorly: the well-installed unit will outperform AND outlast the cheaply-installed one by years. A premium-brand unit installed badly is worse than a builder-grade unit installed properly.

When a system underperforms, customers blame the equipment. Usually the equipment is fine + the install is bad.

HVAC install red flags

Refrigerant line set:

• Loose insulation, gaps where bare copper shows
• Lineset tightly bent (kinked) at outdoor unit
• Not pitched to drain back to compressor
• Suction line in direct sun without UV-resistant insulation
• Long line runs without proper sizing

Indoor coil / air handler:

• Mismatched indoor + outdoor units (per AHRI directory - not all combos are tested as a matched system)
• Coil installed in wrong orientation (upflow on downflow application, etc.)
• Drain pan not pitched to drain
• Secondary drain pan missing on attic install
• Float switch (water sensor) missing
• Filter slot not sealed (bypass air around filter)

Outdoor unit:

• Not on level pad
• Set against the house (no clearance for airflow)
• Surrounded by debris, vegetation (restricts airflow)
• Disconnect missing OR not within sight of unit (NEC required)
• Whip wiring damaged at penetration into unit

Ductwork:

• Crushed flex duct (radius bends with kinks)
• Long flex runs without intermediate support
• Air leaks at joints (no mastic OR foil tape)
• Wrong duct sizing for blower OR system tonnage
• Returns inadequate (single small return for whole-house system)

Thermostat:

• Located on exterior wall (reads wrong temperature)
• Directly above supply register (cold draft on stat)
• In direct sun
• Wired incorrectly (RC + RH jumper missing on dual-transformer system)

Plumbing install red flags

Supply lines:

• Rubber hoses on washing machine (5-year failure life)
• Galvanized still in service (corroded interior reducing flow)
• Unsupported piping (sags + stress at fittings)
• PEX exposed to UV (UV degrades PEX)
• Mixed-material connections without dielectric union (galvanic corrosion)

Drain lines:

• Wrong slope (too steep = water leaves solids; too shallow = standing waste)
• S-trap installed (illegal modern code; siphons water out of trap)
• No vent OR vent improperly located
• Drain run too long from trap (siphoning issue)

Water heater:

• T+P discharge capped OR routed wrong (catastrophic risk)
• Missing expansion tank on closed system
• Missing earthquake straps in seismic areas
• No drain pan OR pan with no drain to safe location
• Cold-water shutoff not within reach
• Improper venting (atmospheric vent next to high-eff sealed combustion?)

Faucet / fixture:

• Missing shutoff valves at fixtures
• Cross-connection (potable + non-potable supplies meet)
• Backflow preventer missing where required (irrigation, boiler feed, hose bibs)

Electrical install red flags

Panel:

• Federal Pacific Stab-Lok (known failure history)
• Zinsco / GTE-Sylvania (similar concerns)
• Double-tapped breakers (one wire intended; two seated; loose)
• Aluminum branch wiring on copper-rated devices (CO/ALR-marked devices required)
• Cobra wire OR knob-and-tube remnants
• Loose breaker connections (sparks/fire risk)
• Missing labels on circuits

Outlets + switches:

• Backstabbed connections (spring-clip; fails over time)
• Reverse polarity (3-light tester reveals)
• Open ground (3-prong outlet without actual ground)
• Outlets near water without GFCI
• Outlets in bedroom without AFCI (modern code)
• Daisy-chained 15A outlets on 20A circuit OR vice-versa
• TR (tamper-resistant) missing on new install

Light fixtures:

• Insulation-contact fixtures without IC-AT rating in attic
• Cover plates missing
• Junction boxes buried in drywall (must remain accessible)
• Wire nuts in inaccessible locations

Service entrance:

• Service drop touching tree branches
• Meter base damaged / weathered
• Grounding electrode (rod, water pipe) not properly bonded

Roofing install red flags

Shingles:

• Wrong nail placement (high nail = blow-off in wind)
• Nail count wrong for wind zone
• Cutting starter strip with utility knife (versus proper starter strip)
• Step flashing missed at wall-to-roof junctions
• Counter-flashing not let into masonry properly
• Drip edge missing at eaves + rakes

Ventilation:

• Soffit vents painted/blocked
• Ridge vent + gable vent both (short-circuits airflow)
• Bath fan duct terminating in attic (covered separately)
• Insufficient NFA for attic size

Underlayment:

• Felt vs synthetic underlayment used inconsistently with shingle warranty requirements
• Ice + water shield missing at eaves in cold climates
• Underlayment torn / wrinkled (no smooth surface to nail to)

Garage door install red flags

• Track misalignment (door binds OR drifts)
• Springs incorrectly sized (door imbalanced)
• Cables frayed
• Opener limit switches wrong (door doesn't fully close OR slams)
• Safety reverse not working (test: place a 2x4 in door path)
• Photo eyes misaligned

Common red flags across all trades

• Hand-written modifications to factory equipment
• Mismatched parts (one brand of breaker in a different brand panel - sometimes not UL-approved combination)
• "Temporary" fixes that became permanent
• Bypassed safety devices (jumpered limit switches, removed pressure switches)
• Equipment installed in wrong location (water heater in unconditioned attic without provisions, etc.)
• Original manufacturer's install instructions not followed (red tags from inspector)

What to do when you find a red flag

Document: photograph it.

Tell the customer: in clear language, what the issue is + the consequence.

Recommend: corrective action OR referral.

Don't bypass it: doing service on top of an unsafe install ties you to the issue when it eventually fails.

Decline if necessary: some red flags (live electrical hazards, gas leaks, missing T+P) require correction before you do any related work.

When the customer says "the previous tech said it was fine"

Some red flags are debatable; some are obvious. If you see something genuinely unsafe (capped T+P, double-tapped breaker, blocked flue), the previous tech's opinion doesn't override safety. Politely:

"I'd want to address this before doing additional work - the previous install isn't safe + my work on top of it would put us both at risk."

References

• Manufacturer install manuals (every piece of equipment)
• IRC + IPC + NEC + IFGC code requirements
• AHRI directory for matched HVAC systems
• Manufacturer warranty requirements (often void if install instructions skipped)
• Manuall internal: Combustion Fundamentals, Pressure Relief Valve Diagnosis, Common Codes Overview