Equipment Installation Problems — All Commercial Sites
Fifteen cross-site equipment problems covering AHUs, RTUs, split systems, rigging, curbs, access, drainage, flexible connectors, weatherproofing, and startup readiness.
What this covers
Use this playbook when installation conditions do not match the plan, the work cannot be completed cleanly, or the crew needs a structured way to inspect the problem before changing the installation.
How to use this playbook
- Identify the exact location, system, installation phase, and affected work.
- Open the closest matching problem below.
- Complete the listed checks before changing or removing installed work.
- Use the field solution only when it matches project requirements and crew direction.
- Apply the prevention note to the next similar installation.
- Stop and escalate whenever the listed stop condition applies.
Problems and field solutions
Rigging · AHUs/RTUs1. Equipment arrives with shipping damage
Open
1. Equipment arrives with shipping damage
What to check
Inspect casing, coils, base rails, doors, fans, and accessories before unloading.
Field solution
Document damage; notify supplier; protect unit; do not install compromised components without disposition.
Prevent it next time
Perform receiving inspection before crane/rigging.
Stop / escalate
Stop if structural, refrigerant, electrical, or fan damage exists.
Rigging · AHU sections2. Sections are rigged from unapproved points
Open
2. Sections are rigged from unapproved points
What to check
Check manufacturer rigging instructions and labels.
Field solution
Reset rigging with approved lifting points, spreader bars, and qualified plan.
Prevent it next time
Review rigging manual before lift.
Stop / escalate
Stop lift immediately.
Setting · Equipment3. Unit is not level and drain pan will not drain
Open
3. Unit is not level and drain pan will not drain
What to check
Check base, curb/frame, isolators, and manufacturer level requirements.
Field solution
Shim/reset support as approved; relevel unit; test drain before connections are finalized.
Prevent it next time
Survey pad/curb before set.
Stop / escalate
Stop startup until drainage is proven.
Connections · AHU/RTU4. Duct weight is carried by unit casing
Open
4. Duct weight is carried by unit casing
What to check
Inspect final supports, transitions, and flexible connectors.
Field solution
Add independent supports; realign duct; reset connector neutral; repair casing if damaged.
Prevent it next time
Install equipment-adjacent supports before connecting.
Stop / escalate
Stop if casing is distorted.
Connections · Flexible connectors5. Connector is stretched tight
Open
5. Connector is stretched tight
What to check
Check alignment and gap.
Field solution
Reposition duct/support or fabricate correct transition; replace connector and leave neutral slack.
Prevent it next time
Do not use connector to make up dimensional error.
Stop / escalate
Stop startup with torn or overstressed connector.
Access · AHU6. Coil pull path is blocked by wall or duct
Open
6. Coil pull path is blocked by wall or duct
What to check
Check submittal service dimensions.
Field solution
Relocate obstruction or unit before completion; maintain full pull path.
Prevent it next time
Mark service envelope on floor/walls during layout.
Stop / escalate
Stop installation if access cannot be achieved.
Access · RTU7. Filter doors cannot open due to gas/electrical/duct routing
Open
7. Filter doors cannot open due to gas/electrical/duct routing
What to check
Check all service-door swings.
Field solution
Reroute services and supports; preserve code and manufacturer clearances.
Prevent it next time
Perform service-access walk before final connections.
Stop / escalate
Stop turnover until access works.
Drainage · Cooling equipment8. Condensate trap is installed from a guessed dimension
Open
8. Condensate trap is installed from a guessed dimension
What to check
Check manufacturer static-pressure trap requirements.
Field solution
Remove and rebuild trap exactly per unit instructions; add cleanout/vent as required; test.
Prevent it next time
Use unit-specific IOM at rough-in.
Stop / escalate
Stop startup until correct.
Controls · Equipment9. Sensor tubing or wiring is pinched during duct connection
Open
9. Sensor tubing or wiring is pinched during duct connection
What to check
Inspect penetrations, grommets, tubing, and harness routes.
Field solution
Repair/replace damaged components; reroute and secure away from sharp edges.
Prevent it next time
Protect controls during mechanical connection.
Stop / escalate
Stop commissioning until signals are verified.
Vibration · Equipment10. Shipping blocks/restraints are left in place
Open
10. Shipping blocks/restraints are left in place
What to check
Check manufacturer startup checklist and visible labels.
Field solution
Remove restraints as instructed; inspect isolators and fan movement.
Prevent it next time
Include shipping-restraint check in turnover list.
Stop / escalate
Stop startup if restraints remain.
Weatherproofing · Outdoor equipment11. Curb or casing joint leaks rainwater
Open
11. Curb or casing joint leaks rainwater
What to check
Check gasket, curb squareness, flashing, panel seams, and penetrations.
Field solution
Coordinate roof/casing repair; reseal with approved system; correct standing water.
Prevent it next time
Inspect weather seals before startup.
Stop / escalate
Stop if water reaches electrical or occupied space.
Orientation · Equipment12. Unit is set backwards relative to duct openings
Open
12. Unit is set backwards relative to duct openings
What to check
Compare unit model/handedness, curb, and drawings.
Field solution
Do not cross-connect; reset unit if feasible or use engineered approved adapter only.
Prevent it next time
Verify orientation during pre-lift meeting.
Stop / escalate
Stop all connections until resolved.
Accessories · Equipment13. Economizer or curb adapter is missing during set
Open
13. Economizer or curb adapter is missing during set
What to check
Check packing list, submittal, and sequence.
Field solution
Delay final set or install accessory per manufacturer-approved sequence; protect opening.
Prevent it next time
Verify all loose-ship accessories before crane day.
Stop / escalate
Stop if later installation would require unsafe rework.
Power Coordination · Equipment14. Disconnect location blocks service panel
Open
14. Disconnect location blocks service panel
What to check
Check electrical layout and service-door swing.
Field solution
Coordinate relocation before final wiring; maintain required clearances.
Prevent it next time
Overlay electrical and mechanical service zones.
Stop / escalate
Stop energization until access is safe.
Startup Handoff · Equipment15. Unit is released for startup with dirty filters and debris
Open
15. Unit is released for startup with dirty filters and debris
What to check
Inspect filters, coil, fan section, drain pan, and duct cleanliness.
Field solution
Clean unit and connected duct; install correct filters; close panels; document readiness.
Prevent it next time
Use formal pre-start checklist.
Stop / escalate
Stop startup until clean and complete.
Check
- Current approved drawings and submittals
- Actual field dimensions and access
- Support, joint, equipment, and life-safety requirements
- Whether the correction changes design intent or another trade's work
Warnings
- Do not solve coordination problems by crushing, stretching, or forcing duct and equipment.
- Do not bury access, dampers, controls, filters, coils, cleanouts, or service panels.
- Do not treat lift, rigging, welding, refrigerant, gas, electrical, structural, or life-safety work as apprentice-only work.
Stop and ask
- Stop when the correction changes route, size, pressure class, listed assembly, equipment connection, structure, life-safety function, or another trade's approved work.