How to Compare HVAC Contractor Bids

Why Most Homeowners Choose Wrong

You get three bids: $5,500, $6,200, and $7,800. Which do you choose? If you said "the $5,500 one," you're making the same mistake 60% of homeowners make. The cheapest bid often comes from contractors who cut corners on sizing, installation, or equipment quality—problems that cost thousands more over 10-15 years.

Before requesting bids, calculate your actual cooling load using our BTU calculator. This gives you a baseline to evaluate whether contractors are sizing correctly or just guessing.

What to Request from Each Contractor

1. Load Calculation Documentation

Ask: "Can you provide your Manual J load calculation?" Quality contractors will happily share their analysis showing:

• Room-by-room BTU loads
• Total cooling capacity needed
• Design temperatures used
• Insulation levels assumed
• Window types and orientations

Compare their calculated load against your BTU calculator result. Should match within 10-15%. Big differences (>25%) indicate poor sizing methodology.

2. Detailed Equipment Specifications

Request exact model numbers for all equipment:

• Outdoor unit: Manufacturer, model, tonnage, SEER2 rating
• Indoor unit: Evaporator coil or air handler model
• Thermostat: Programmable? Smart? Which model?
• Ductwork: New ducts, modifications, or using existing?

Use model numbers to research efficiency ratings, reliability reviews, and warranty terms independently.

3. Installation Scope of Work

Get written details on what's included:

• Equipment removal and disposal (old unit)
• Pad or mounting hardware
• Electrical work (new circuit? Disconnect switch?)
• Refrigerant line set (new or reuse existing?)
• Duct sealing or repairs
• Thermostat installation location
• Startup and commissioning
• Cleanup and haul-away

Cheap bids often exclude duct repairs, electrical upgrades, or proper disposal—surprise costs that appear later.

4. Warranty Information

• Manufacturer warranty: Usually 5-10 years on parts
• Labor warranty: Contractor's guarantee on installation (1-5 years typical)
• Extended warranties: Optional coverage terms and cost

Some contractors offer longer labor warranties as proof of installation quality confidence.

Bid Comparison Scorecard

Specific Questions to Ask Each Contractor

Sizing & Design Questions:

1. "How did you determine the system size?" → Should mention Manual J, room measurements, insulation levels
2. "Can I see your load calculation?" → Quality contractors share their work
3. "What design temperatures did you use?" → Should match local 99% summer temps (find yours with climate zone guide)
4. "Did you account for insulation and window quality?" → Major load factors, must be included
5. "How much safety factor did you add?" → 10-15% acceptable, 25%+ indicates oversizing tendency

Equipment Questions:

1. "What's the exact model number?" → Allows independent research on efficiency, reviews, warranty
2. "Why did you recommend this brand/model?" → Should explain efficiency, reliability, features—not just "it's what I use"
3. "What's the SEER2 rating?" → Efficiency metric; 14-16 is standard, 18+ is premium
4. "Is this equipment matched/compatible?" → Outdoor unit + indoor coil must be manufacturer-matched for warranty
5. "What refrigerant does it use?" → R-410A is standard, R-32 is newer (more efficient), avoid R-22 (obsolete)

Installation Questions:

1. "Will you seal the ductwork?" → Leaky ducts waste 20-30% of cooling; sealing is critical
2. "Do you do a load calculation for duct sizing?" → Room-by-room loads determine duct sizes
3. "How do you charge the refrigerant?" → Should use superheat/subcooling method, not just "add until full"
4. "What electrical work is included?" → May need new 240V circuit, disconnect box
5. "How long will installation take?" → 1-2 days typical for straight replacement, 3-5 days for full system with ductwork

Business/Warranty Questions:

1. "Are you licensed and insured?" → Verify license number with state board
2. "Who does the actual installation?" → Employees vs subcontractors; employees = more accountability
3. "What's your labor warranty?" → 1 year minimum, 3-5 years better
4. "What maintenance do you recommend?" → Annual tune-ups extend life; some offer maintenance plans
5. "Do you offer financing?" → 0% for 12-24 months is common for larger systems

Case Study: Three Bids Compared

Scenario: 1,800 sq ft home, Zone 3, needs full system replacement

Bid A: $5,200 (Budget Contractor)

• Sizing: "3 tons is standard for 1,800 sq ft homes"
• Equipment: Generic brand, 14 SEER2, no model number provided
• Installation: "Replace equipment, test and go"—no duct sealing mentioned
• Warranty: 5 years parts, 90 days labor
• Score: 420/1000 → High risk

Problems: Rule-of-thumb sizing (likely oversized), cheap equipment, minimal warranty, vague installation scope. Homeowner calculated 26,000 BTU actual load using BTU calculator—this contractor proposed 36,000 BTU (39% oversized).

Bid B: $6,800 (Quality Contractor)

• Sizing: Provided Manual J showing 24,000 BTU load → 2-ton system
• Equipment: Lennox XC16 (16 SEER2), model numbers included, 10-year parts warranty
• Installation: Detailed SOW: duct sealing, new thermostat, refrigerant charging by superheat, disposal
• Warranty: 10 years parts + 5 years labor
• Score: 875/1000 → Excellent

Verdict: Proper sizing (matched homeowner's calculations), quality tier-1 equipment, comprehensive installation, strong warranty. $1,600 more than Bid A but saves $300-500/year in energy costs = payback in 4-5 years.

Bid C: $8,400 (Premium Contractor)

• Sizing: Manual J showing 24,000 BTU → 2-ton system
• Equipment: Carrier Infinity 21 (18 SEER2, variable-speed compressor), Wi-Fi thermostat
• Installation: Same scope as Bid B + duct performance testing (blower door test)
• Warranty: 10 years parts + 10 years labor
• Score: 925/1000 → Excellent

Verdict: Top-tier equipment with best efficiency and comfort (variable-speed = fewer temperature swings). Premium warranty. $1,600 more than Bid B saves extra $150-200/year in energy = 10-year payback. Best choice if budget allows and you plan to stay in home 10+ years.

Homeowner's Decision:

Chose Bid B. Bid A's oversizing and poor warranty were dealbreakers. Bid C's extra $1,600 didn't justify modest additional savings for this homeowner's 7-year ownership timeline.

Red Flags to Watch For

Negotiation Tips

1. Use Your Calculator Results as Leverage

If your BTU calculator shows 22,000 BTU but contractor proposes 36,000 BTU (3 tons), ask: "My calculations show 22k BTU. Can you explain why you're recommending 50% more capacity?"

Forces contractor to justify sizing or recalculate.

2. Compare Apples-to-Apples

Ask higher-priced contractors: "Bid A is $6,200 for a 3-ton 14 SEER2 system. Your bid is $7,800 for a 2.5-ton 16 SEER2 system. Can you match their equipment and price, or explain why yours is worth the premium?"

Either get price concessions or learn what justifies higher cost.

3. Negotiate Scope, Not Just Price

Instead of "Can you discount 10%?" ask: "Can you include duct sealing and a programmable thermostat at your quoted price?" Improves value without pure price-cutting.

4. Ask for Mid-Tier Equipment

If premium equipment is out of budget: "Your 18 SEER2 system is too expensive. Can you requote with a 16 SEER2 model from the same brand?" Usually saves $1,000-2,000 while keeping quality installation.

Final Checklist Before Signing

Resources to Compare Bids

• BTU Calculator: Calculate your load independently to verify contractor sizing
• Manual J Guide: Understand proper load calculation methodology
• Multi-Room Planner: Break down loads by room for duct sizing verification
• Climate Zone Guide: Verify contractor used correct design temperatures
• Oversizing Problem: Why bigger isn't better—avoid upselling tactics