Heating, Ventilation and Air-Conditioning (HVAC)

1 69 heating , Ventilationand Air-Conditioning ( hvac )Energy Code RequirementsThe energy requirements of the building code that apply to hvac instal-lations (ECCCNYS Section 503) are in addition to any plumbing, mechan-ical, and fuel gas codes that apply to these systems. Although it is gener-ally the hvac installer s responsibility to follow these requirements,because they are in the building code it may be up to the builder to knowwhat they are and to communicate them to the subs for a given s a summary of the hvac requirements.

2 Remember that theserequirements generally apply to all residential buildings, but more com-plex mechanical systems typically found in multifamily residences mayhave to meet additional requirements see ECCCNYS Section 503 formore detail. Heat loss calculations and system sizing (ECCCNYS Chapter 3) heating and cooling load calculations must bedone according to a specified process. Air conditioning Contractors of America (ACCA) Manual J(seeAppendix B for ordering information) is required by the 2000 IRCOne and Two Family Dwelling Code (see Section ).

3 Thedesign parameters used for these calculations are given in ECCCNYSC hapter 3. hvac system efficiencies The minimum efficiency requirementsfor hvac systems are given in ECCCNYS Note that code min-imums for efficiency follow federal minimum efficiency standards. Seefollowing table and the next bullet for more Boilers (oil and gas)Annual Fuel Utilization Efficiency80 Furnaces (oil and gas)Annual Fuel Utilization Efficiency78 Heat Pumps (air source) heating Seasonal Performance Air ConditioningSeasonal Energy Efficiency Ratio10 heating system trade-offs Many boilers and furnaces are more effi-cient than the code minimums.

4 You can take credit in any of the com-pliance methods for systems with higher than minimum efficiency. Getthe equipment efficiency ratings from your hvac installer (or subcon-tractors you have worked with) beforeyou do the compliance a designer or builder you can specify high levels of efficiency, whichmakes it easier to meet the code. However, be careful to know inadvance what your requirements are, and how much the upgrade costs. hvac controls (ECCCNYS and ) Temperaturecontrols must include the capacity to be set to 55 degrees or lower(for heating ) and/or 85 degrees or higher (for cooling).

5 Thermostatsused to control heating and cooling simultaneously must have a tem-perature range (of at least 5 degrees) within which calls for heatingand cooling are either suspended or reduced. Similarly, humidistatsmust have the capacity to prevent energy consumption (suspendoperation) between 30 and 60% relative humidity. Heat pumps thatinclude auxiliary electric resistance heaters must have controls thatlock out the auxiliary heaters above a preset outdoor temperature.

6 All mechanical Ventilation systems must have controls to shut downwhen Ventilation is not required. When the system is shut down,automatic or gravity-driven dampers at the points of intake andexhaust must be closed. Duct and pipe insulationis required for all hvac ductwork andpipes in unconditioned spaces, as indicated in ECCCNYS are exceptionsfor return ducts in basements and ducts or pipesinside hvac equipment. For most single family work, the insulationmust meet the levels shown in the following table.

7 Note that flex ductmust have R-value labels on the outside jacket (ECCCNYS ).Table Duct and Pipe Insulation LevelsDucts in unconditioned spaceHydronic pipes in any unconditioned spaceSupply Return Returnup to 2"over 2"runouts toductsducts inducts inpipepipeindividualuncondi-all otherdiameterdiameterterminals, up tioned uncondi-to 12' longattic ortionedoutsidespacesR-8 R-4R-2R-4 (1")R-6 (1-1/2")R-2 (1/2")70 HVAC9 HVAC71 HVAC9 hvac Duct sealingis required on all low-pressure ductwork ( ). All portions of stud bays or joist cavities used as ductworkmust also be sealed.

8 All connections and seams (except longitudinaljoints that lock) must be sealed with either mastic or fibrous tapeembedded in mastic (see Figure ). Tapes meeting UL 181A may beused for rigid fiber ducts. Tapes meeting UL 181B may be used for flexducts. Duct tape is not allowed for duct sealing. Written materialsdescribing regular maintenance actions must beleft with all hvac and water heating equipment (ECCCNYS ). Alabel with a reference to such material is also STAR Mechanical VentilationThere is little emphasis on indoor Ventilation in building codes.

9 Mostbuilders meet requirements for natural Ventilation by accident, withordinary window and door openings. In New York however, everyENERGY STAR Labeled New Home must be equipped with amechanical Ventilation mechanical Ventilation pro-vides the following benefits: Healthier indoor air ASHRAE recommends that residential build-ings be maintained at 30 to 60% relative humidity for optimum Some biological contaminants thrive in low or high humidity,but most are minimized in this range.

10 How do you control the humid-ity? In any climate and in any season, the first step is to control the airexchange rate. In the winter, dryness is caused by excess air leakage;when dry outdoor air is heated, the relative humidity drops. Highhumidity on the other hand, is often caused by underventilation, andpoor source exhaust for moisture-producing activities such as cookingand bathing. Control the dryness by limiting air leakage, and controlthe moisture by ventilating the house. In the summer, the only way tocontrol humidity is with mechanical dehumidification or properlysized air conditioning systems (see pages 113-114).