1. What is an HVAC Unit Size Calculator?

Definition: This calculator converts BTU (British Thermal Unit) cooling capacity to tons, which is the standard measurement for HVAC system sizing.

Purpose: It helps homeowners, HVAC professionals, and contractors properly size air conditioning systems for buildings.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \text{Tons} \) — HVAC unit capacity (tons)
• \( \text{BTUs} \) — British Thermal Units per hour (BTU/hr)

Explanation: One ton of cooling capacity equals 12,000 BTU/hr. This conversion helps match HVAC systems to building cooling requirements.

3. Importance of Proper HVAC Sizing

Details: Correct sizing ensures energy efficiency, proper humidity control, system longevity, and prevents short cycling or inadequate cooling.

4. Using the Calculator

Tips: Enter the total BTU requirement (from manual J calculation or rule of thumb). Value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why 12,000 BTU per ton?
A: This originates from the amount of heat needed to melt one ton of ice in 24 hours (288,000 BTU/24hr = 12,000 BTU/hr).

Q2: How do I determine my BTU requirements?
A: Professional Manual J calculations consider square footage, insulation, windows, climate, and other factors.

Q3: What's a typical tonnage for residential homes?
A: Most homes need 1-5 tons (12,000-60,000 BTU), with about 1 ton per 400-600 sq ft depending on climate and insulation.

Q4: Can I use this for heat pumps?
A: Yes, the calculation works the same for cooling capacity of heat pump systems.

Q5: Should I round up the calculated tonnage?
A: HVAC systems come in standard sizes (1.5, 2, 2.5, 3, etc. tons). Professional installation should determine final sizing.