Understanding Garage Heating
Proper garage heater sizing ensures comfort and efficiency while considering space characteristics, insulation levels, and usage patterns.
- Heat Load Factors Base load: 30-35 BTU/sq.ft Ceiling height factor: +15% per foot over 8' Window factor: +10% per window Door factor: +20% per exterior door Vehicle impact: +5,000 BTU per car
- Climate Considerations Zone 1-2: 30 BTU/sq.ft Zone 3-4: 35 BTU/sq.ft Zone 5-6: 40 BTU/sq.ft Zone 7-8: 45 BTU/sq.ft Temperature differential: Design temp to 68°F
- Insulation Impact R-13 walls: Base calculation R-19 walls: -10% BTU required R-30 ceiling: Base calculation R-38 ceiling: -15% BTU required Air sealing: -5% BTU required
- Usage Patterns Occasional use: 0.75 factor Regular use: 1.0 factor Workshop: 1.25 factor Living space: 1.5 factor Recovery time: 30-45 minutes
Heater Types
Forced Air
Efficiency: 80-95% AFUE. Air throw: 25-30 feet. Mount height: 7-10 feet. CFM: 75-150 per 10,000 BTU. Recovery: 15-20 minutes.
Radiant
Efficiency: 90-99%. Coverage: 100-150 sq.ft per unit. Mount height: 8-12 feet. Angle: 30-45 degrees. Zone control capable.
Infrared
Efficiency: 85-90%. Direct heating zone: 8-10 foot radius. Mounting: 8-15 feet high. Power: 20-40 watts/sq.ft coverage.
Unit Heater
Efficiency: 80-82%. Throw distance: 15-50 feet. Mounting: Ceiling/wall bracket. BTU range: 30,000-200,000. Multiple stages available.
Installation Requirements
- Electrical Requirements Circuit sizing: - 5kW: 30A/240V - 7.5kW: 40A/240V - 10kW: 50A/240V Wire gauge: 10-6 AWG GFCI protection required
- Gas Requirements Natural gas pressure: 5-7" WC Propane pressure: 11-13" WC Pipe size: 1/2"-3/4" typical Flex connector: 24-36" length Annual inspection required
- Ventilation Needs Fresh air: 1 sq.in per 1,000 BTU Exhaust: Power vented/sealed CO detector: Required Combustion air: 50 cu.ft per 1,000 BTU Clearances: Per manufacturer
- Mounting Specifications Height: 8-12 feet typical Wall bracket: 500 lb capacity Ceiling mount: 3/8" rod minimum Vibration isolation: Required Level tolerance: ±1/2 degree
Performance Factors
- Efficiency Ratings AFUE standards: - Minimum: 80% - Mid-efficiency: 83-89% - High-efficiency: 90-97% Thermal efficiency: 78-82% Radiant efficiency: 85-92%
- Operating Costs Natural gas: $0.40-0.60/hour Propane: $0.80-1.20/hour Electric: $1.00-1.50/hour Maintenance: $100-200/year Life expectancy: 15-20 years
- Temperature Control Thermostat accuracy: ±1°F Staging capability: 2-3 stages Setback savings: 10-20% Recovery time: 20-30 minutes Zone control: Optional
- Safety Features High limit switch Tip-over protection Oxygen depletion sensor Flame supervision Over-temperature protection
Maintenance Schedule
- Monthly Tasks Filter inspection/change Visual check of operation Thermostat accuracy check Clearance verification Safety system test
- Annual Service Burner cleaning Heat exchanger inspection Electrical connection check Gas pressure verification Efficiency testing
- Safety Inspections CO detector testing Ventilation verification Gas leak check Exhaust system inspection Emergency shutdown test
- Replacement Parts Filters: 3-6 months Igniter: 3-5 years Thermocouple: 5-7 years Blower motor: 8-12 years Heat exchanger: 15-20 years