Line up each bid by the same items: load calculation, exact model numbers (outdoor and indoor), efficiency ratings, scope of duct, electrical, and venting work, permits, rebate paperwork, commissioning tests, labor warranty, and payment terms. The lowest total often leaves out items another bid includes.
Technical Consideration
Proposal comparison checklist
| Item | What to look for |
|---|---|
| Sizing method | Manual J load calculation, not rule of thumb |
| Equipment | Full model numbers for every component |
| Efficiency | SEER2 / HSPF2 / AFUE and matched-system rating |
| Scope | Ducts, returns, electrical, venting, drain, pad, line set |
| Permits | Who pulls them; inspection included |
| Rebates | Who files; eligible models confirmed |
| Commissioning | Charge, airflow, static pressure, combustion tested |
| Warranty | Parts and labor terms in writing |
| Payment | Deposit, schedule, and final payment after inspection |
Why do bids differ so much?
Contractors include different scope: one may replace the line set, add a return, and pull a permit; another may not.
Normalize scope before comparing price.
What does a matched system mean?
The outdoor unit, indoor coil, and air handler or furnace are certified together for the advertised efficiency.
Mismatched components can underperform and may affect warranties and rebates.
What red flags should I watch for?
No load calculation, vague model numbers, pressure to sign the same day, or a large deposit before permits are issued.
Also verify the Delaware license of the company doing the work.
Related services in Wilmington
- AC Installation & Replacement in Wilmington, DE
- Furnace Installation & Replacement in Wilmington, DE
- Heat Pump Installation in Wilmington, DE
- Boiler Replacement in Wilmington, DE
Local verification resources
Before authorizing work, use the Delaware license lookup. For projects that may require approval, consult the City of Wilmington permit information or the authority serving the property.