HVAC for Energy Advisors & Raters
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Brett Dillon presented on HVAC design and code requirements. He discussed performing load calculations using Manual J and selecting equipment using Manual S. He emphasized using OEM performance data for equipment selection. He also reviewed requirements for duct design using Manual D, including sizing ducts, calculating airflow, and required static pressures. Throughout, he stressed that code requires following Manual J, S, and D for new installations and replacements of HVAC systems.
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HVAC for Energy Advisors & Raters
- 1. HVAC for Energy Advisors & Raters Brett Dillon CEO Midwest Regional Energy Conference
- 2. About Me • Author of: • Guide to HVAC Design, Construction & Commissioning • Developer of: • ACCA RSI Verifier Manual & Certification Program • NATE HVAC Verifier Training Program
- 3. AHRI Capacity vs OEM Capacity Manual J Manual S Manual D
- 5. AHRI Data • Region IV • 80°F indoor cooling test temperature • 67°F indoor wet bulb temperature • 90°F outdoor test temperature • 47°F outdoor heating test temperature • 17°F outdoor heating test temperature
- 6. Code Requirements Manual J Manual S Manual D Blueprints & Specifications Design Temperatures Orientation Internal Loads Ventilation Infiltration Duct System Manual J OEM Performance Manual J Material Devices Length
- 7. 2009 IRC Requirements • Outdoor Thermostat for heat pumps • N1103.1.2 • R-8 ducts in attics • N1103.2.1 • Ducts sealed and tested • N1103.2.2 • Repairs/replacements of existing systems • M1202.1 • HVAC sizing based upon Manuals S & J • M1401.3 • Heat Pump return area • M1403.1 • Duct Design according to Manual D • M1601.1
- 8. Replacement / Repairs of Systems • Meet requirements for new installations • M1202.1
- 9. Code Required • Manual J & S, M1401.3 (2009) • Manual D, M1601.1 (2009) • Ventilation, M1507.3 (2012) • 403.5 Mechanical ventilation (Mandatory). Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating. Code
- 10. System Concept Load Calculation Equipment Selection Air Distribution Duct Size Calculation Adjust, Test & Balance Manual RS Manual J Manual T Manual S Manual D
- 11. Manual J
- 12. Manual J • 99% • 1% • Room-by-Room • Process, not software Code
- 13. Manual J • Indoor Design Temperatures • Outdoor Design Temperatures • Windows • Walls • Ceilings • Floors Code • Infiltration • Appliances • Occupants • Ducts • Ventilation
- 14. Infiltration • 2009 IRC • Maximum 7 ACH50 Code
- 15. Internal Loads • Appliances • 1200 Btu/hr • 2400 Btu/hr • 3600 Btu/hr • Occupants • BR + 1 • 230 Btu/hr x occupants Code
- 16. Duct Loads • Location • Leakage • Code maximum Code
- 17. Ductwork • R-8 • R-6 • Sealing • Outside air inlets Code
- 18. 2009 IRC • N1103.2.2 Mandatory duct testing • Post-Construction, 8% leakage to outside or 12% total leakage • Rough-in, 6% total leakage, 4% if air handler not installed Code
- 20. Manual S
- 21. Systems • Furnace, > 0.50 i.w.c. • Condensate drain • Secondary drain pan • Suction lines insulated • Combustion air • Heat pump returns Code
- 22. Systems • Furnaces = programmable T-stat • Heat pumps = outdoor T-stat Code
- 23. Equipment Selection • Heating output, Btu/hr < 140% load • Total Cooling, Btu/hr <115% load • Sensible capacity • Latent capacity • Airhandler CFM • Auxiliary Heating Code
- 26. Manual D
- 27. Manual D • Sizing Ducts • Friction Rate • (pressure drop x 100) / total effective length • Slide rule • Static pressure Code
- 28. Manual D • Peak loss = 1967 Btu/hr • CFM = 1,967 / (1.1 x ∆T) • ∆T = ℉ between return & supply • Heat pumps, 25℉ • Furnaces, 55℉ • CFM = 1967 / (1.1 x 25) = 1967 / 27.5 = 72 • CFM = 1967 / (1.1 x 55) = Code
- 29. Manual D • Peak gain = 1189 Btu/hr • Sensible gain = 932 Btu/hr • Latent gain = 257 Btu/hr • SHR = 932 / 1189 = 0.78 • CFM = 932 / (1.1 x ∆T) • ∆T = ℉ between return & supply • SHR < 0.80, 21℉ • CFM = 932 / (1.1 x 21) = 932 / 23.1 = < 0.80 21℉ 0.80 - 0.85 19℉ > 0.85 17℉ Code
- 30. Manual D • Required under IRC M1601.1 • Implies room-by-room load calculation must be performed • CFM • SHR • ΔT supply-return • Sensible load • Friction rate • Pressure drop x 100 / total effective length Code
- 31. Supply Duct Sizing • What temperature does the air need to be to meet the load? • How many CFM of air must be delivered to meet the load? • Sensible Load / (1.1 x ΔT)
- 32. Return Airflow • 350 fpm • Return register face velocity < 400 fpm • 90º bend between register & airhandler
- 33. Sizing Return Ducts • Sized according to Manual D –Returns should be sized properly •IRC M1403.1, heat pumps need > 6 sq in / 1,000 Btu/hour capacity (2 ton unit at least 14” duct) –All areas that are conditioned should have an adequate return path •And undercutting doors 1” isn’t enough! Code
- 36. Other Sources • http://www.acca.org/standards/acca-speed-sheets/ • http://www.acca.org/qa/resources/ • RESNET/NATE HVAC Verifier Training & Certification
- 37. Questions?