ENERGY STAR v3.0 HVAC Checklists

Transcription

1 IMPROVING THE BUILT ENVIRONMENT ENERGY STAR v3.0 HVAC Checklists Hands on Practice, Tips, and Lessons Learned Srikanth Puttagunta, P.E. Certified RESNET HERS Rater and Quality Assurance Designee Steven Winter Associates, Inc.

2 What are you responsibilities? Inform client of the items that you will need to verify specific to HVAC: HVAC Contractor is Certified by ACCA HVAC System Quality Installation Contractor Checklist is submitted with supporting documentation HVAC System Quality Installation Rater Checklist Checklist: 01_clean_fillable_508.pdf? Guidebook: Installation_Rater_Checklist_Guidebook_Rev04_v6_FINAL_508.pdf?8e59-ffa4

3 Certified HVAC Contractor The following language is included in our Compliant Resolution Letter which our Raters send to a Client as soon as our Rater is under contract. To participate in the EPA s ENERGY STAR program, the builder and HVAC contractor are required to register, complete training requirements, and maintain credentials which can be accessed through the following link howwelcome&p_code=hbuilder

4 Review Load Calcs Manual J v8, 2009 ASHRAE, or Other. If a load calculation method other than Manual J v8 is used, we require our Clients to have this method pre-approved by SWA (prior to HVAC systems being specified and installed).

5 Review Manual J Calcs There are several software packages available that are designed to do these Manual J load calculations, including (but not limited to): Wrightsoft s Right-Suite Elite Software s RHVAC Adtek Software s AccuLoad Examples of commonly used software that do not meet the requirements: HVAC Computer Systems HVAC Calc 4.0 (7th edition of ACCA s Manual J) Trane s Trace 700 (commercial sizing tool) Carrier s HAP (commercial sizing tool) Elite Software s CHVAC (commercial sizing tool) Thomas & Associates HEATLOSS version 3.2 (7th edition of ACCA s Manual J)

6 Review Manual J Calcs Outdoor design temperatures are equal to the 1% and 99% ACCA Manual J design temperatures for contractor-designated design location What does a 1% or 99% outdoor design conditions mean? This is the dry-bulb temperature that corresponds to annual cumulative frequency of occurrence. This value represents the value that is exceeded on average by the indicated percentage of the total number of hours in a year (8,760 hrs). For example, the 1.0% outdoor cooling design temperature for Hartford, CT is 88 F. This means that the outdoor conditions only exceed 88 F on average for 87.6 hours per year, or 1.0% of the year.

7 Review Manual J Calcs Outdoor design temperatures are equal to the 1% and 99% ACCA Manual J design temperatures for contractor-designated design location It should be noted that extreme weather conditions can always occur that may leave your air conditioning system with temporary limits on delivering full comfort performance. This is much like selecting siding, roofing and window materials to handle very harsh weather conditions, but not extreme weather such as hurricanes and tornadoes. /Outdoor_Design_Conditions_508.pdf?8e59-ffa4

8 Review Manual J Calcs Outdoor design temperatures are equal to the 1% and 99% ACCA Manual J design temperatures for contractor-designated design location If contractor uses alternative numbers, need documentation that justifies their decision (micro-climate, monitored data, etc.). Rater is not required to determine validity of justification. Through end of 2012, allowed to be within ±5 F of ACCA Manual J design temperature.

9 Example Manual J

10 Review Manual J Calcs Home orientation matches orientation of rated home Through end of 2012, can be based on worst orientation design if the house plan has multiple configurations. Beginning in 2013, must be specific to rated home.

11 Review Manual J Calcs Number of Occupants equals number of occupants in rated home. If unknown, this should be (# of bedrooms + 1). A bedroom is defined by RESNET as a room or space 70 sq. ft. or greater in size, with egress window and closet, used or intended to be used for sleeping. A "den", "library", or "home office" with a closet, egress window, and 70 sq. ft. or greater or other similar rooms shall count as a bedroom, but living rooms and foyers shall not. If there is a need to accommodate a significant number of temporary occupants (guests) on a regular or sporadic basis, a supplemental cooling system (i.e., mini-split unit) or a variable volume zoning system should be utilized.

12 Review Manual J Calcs Conditioned floor area is within ±10% of conditioned floor area of rated home Window area is within ±10% of calculated window area of rated home Predominant window SHGC is within 0.1 of predominant value in rated home Compare HERS model take-offs with load calc inputs

13 Review Manual S Calcs If the design latent capacity is not met, then they should consider including a dehumidification system to address this shortfall Listed latent cooling capacity exceeds design latent heat gain Listed sensible cooling capacity exceeds design sensible heat gain Listed total cooling capacity is % (or % for Heat Pumps in Climate Zones 4-8) of design total heat gain, or next nominal size

14 Review Manual S Calcs How to handle equipment sizing when multi-stage forced-air systems are specified? Always based on full-load capacity.

15 Review Equipment Selection HVAC manufacturer and model numbers on installed equipment, contractor checklist, and AHRI certificate or OEM catalog data all match. Request all of this documentation before the HVAC rough-in! Won t have the installed equipment to verify, but can review the model number of equipment being ordered. If system sizing is wrong, difficult to correct later on. Equipment could potentially be swapped, but duct-sizing will likely be oversized.

16 Our HVAC Contractor Submittals Equipment Data Device Pressure Losses (DPL - in.wc.) Manufacturer Carrier Cooling Coil Incl. Air Handler/Furnace Model # 58MVC Heat Exchanger Incl. AFUE / HSPF / COP 95% AFUE Supply Diffusers 0.03 Heating Capacity (Btuh) 74,000 Return Grilles 0.03 Condensing Unit Model # 24APA Filter 0.24 Cooling Coil Model # CAP**3621A Humidifier N/A Air Conditioning Size (tons) 2.0 Balancing Dampers N/A Air Volume (CFM) 700 Other Devices 0.03 SEER Rating / EER Rating 16.0 / 13.2 Total DPL 0.33 Cooling Capacity (Btuh) 24,600 Fliter Type MERV 8 Available Static Pressure (ASP - in.wc.) 0.42 External Static 2012 Steven Pressure Winter (ESP Associates, - in.wc.) Inc. All rights 0.75 reserved. Total Equivalent Length (TEL - ft) 363 Fan Speed variable speed ECM Design Friction Rate [FR=(ASP/TEL)*100] 0.12

17 Our HVAC Contractor Submittals For hydronic systems, a schematic displaying room-by-room building loads and the required pipe length needed to provide the Btus should be shown. The specific type of heat emitters used in the design should be specified in the documentation. For unducted systems, a schematic is still needed that identifies where systems will be located and which rooms will be serviced by each unit.

18 AHRI Directory Contractor should submit this to you, but if they don t/won t, then here are some tips: ages/home.aspx Often there are letters that can vary so AHRI uses ( ) or * to cover multiple options under the same rating. Put in the least amount information to start with (manufacturer, 3-5 letters/numbers of outdoor unit and furnace, and first letter/number of indoor coil). Take a look at what pops up and then revise as needed. If nothing pops up, remove some more letters until something pops up.

19 HVAC Contractor Checklist

20 HVAC Contractor Checklist

21 Review System Commissioning Using reported liquid line or suction line pressure, corresponding temperature matches reported condenser or evaporator saturation temperature (+/- 3 degrees) Did the HVAC contractor read the Pressure/Temperature chart correctly? Calculated subcooling or superheat value equals reported target subcooling or superheat temperature

22 Example

23 Subcooling Subcooling is the temperature of a fluid below its boiling point (liquid saturation temperature). OUTDOOR (T, RH, Sol, Wind) Input Power INDOOR (T,RH) Airflow Condenser T cond, in T evap, out T sup RH sup T cond p T evap T cond, air Compressor p TXV Evaporator T cond, out T evap, in T ret Fan RH ret HEAT PUMP IN COOLING MODE Subcooling [ o F] = Condenser Temp at Saturation Condenser Outlet Temp

24 Long Line Lengths

25 Superheat Superheat is the temperature of a fluid above its boiling point (liquid saturation temperature). OUTDOOR (T, RH, Sol, Wind) Input Power INDOOR (T,RH) Airflow Condenser T cond, in T evap, out T sup RH sup T cond p T evap T cond, air Compressor p TXV Evaporator T cond, out T evap, in T ret Fan RH ret HEAT PUMP IN COOLING MODE Superheat [ o F] = Evaporator Outlet Temp Evaporator Temp at vapor point

26 Verify Static Pressure 1.3 Rater-verified supply & return duct static pressure<110% of contractor values You should not be drilling into the ductwork to be making these measurements. Simply use the holes that the contractor used when taking their measurements you are just verifying test results. Depending on return side hole, may need to remove filter during this test.

27 HVAC Contractors Checklist

28 Verify Static Pressure Use a static pressure probe. Make sure sensor is pointing in direction of flow as the holes must be perpendicular to the direction of flow. Air Conditioners and Heat Pumps include the coil in their ESP test, while gas furnaces with air conditioners attached do not.

29 Verify Static Pressure

30 HVAC Contractors Checklist

31 Duct Quality Installation 2.1 Connections and routing of ductwork completed without kinks or sharp bends. 2.2 No excessive coiled or looped flexible ductwork.

32 Duct Quality Installation 2.3 Flexible ducts in unconditioned space not installed in cavities smaller than outer duct diameter; in conditioned space not installed in cavities smaller than inner duct diameter 2.4 Flexible ducts supported at intervals as recommended by mfr. but at a distance < 5 ft. Recommend 2 straps.

33 Duct Quality Installation 2.5 Building cavities not used as supply or return ducts unless they meet items 3.2, 3.3, 4.1, and 4.2 of this checklist. [Insulated and Sealed] 2.6 HVAC ducts, cavities used as ducts, and combustion inlets and outlets may pass perpendicularly through exterior walls but shall not be run within exterior walls unless at least R-6 continuous insulation is provided on exterior side of the cavity, along with an interior and exterior air barrier where required by the Thermal Enclosure System Rater Checklist.

34 Duct Quality Installation 2.7 Quantity & location of supply and return duct terminals match contractor balancing report. Design New Target Final Deviation Size Bedroom 1 (office) 90 CFM 98 CFM 98 CFM 0% 8" x 6" x 8" Bedroom CFM 146 CFM 141 CFM -3% 10" x 6" x 8" Master Bedroom 166 CFM 181 CFM 185 CFM 2% 10" x 6" x 9" Living Room 150 CFM 164 CFM 168 CFM 2% 10" x 6" x 9" Kitchen/Family 260 CFM 283 CFM 278 CFM -2% 12" x 8" x 12" Total 800 CFM 868 CFM 870 CFM

35 Duct Quality Installation 2.8 Bedrooms pressure-balanced using any combination of transfer grills, jump ducts, dedicated return ducts, and/or undercut doors to either: provide 1 sq. in. of free area opening per 1 CFM of supply air, as reported on the contractor-provided balancing report; or achieve a Rater-measured pressure differential < 3 Pa (0.012 in. w.c.) with respect to the main body of the house when bedroom doors are closed and the air handler is operating.

36 Duct Insulation

37 Duct Leakage Per system requirements. 5 CFM25 per 100 sq ft. for home 1,200 ft 2 Needs to be testing at project completion as all components (air handler and register grilles) need to be installed. Just because ducts are located in conditioned space, don t slack on duct sealing. We are finding homes are having a tough time meeting total even when leakage to outside is basically zero. If supply-only connected into AHU, need have access point or damper to seal off outdoor air supply duct.

38 Whole-House Ventilation 5.1 Rater-measured ventilation rate is within % of HVAC contractor design value. For HRV/ERV or supply-only ventilation, using a low-flow balometer can be difficult. I find it easiest to use a hot-wire anemometer to measure flow in the ductwork.

39 Controls - Does the HVAC Work? 6.1 Air flow is produced when central HVAC fan is energized (set thermostat to fan ). 6.2 Cool air flow is produced when the cooling cycle is energized (set thermostat to cool ). 6.3 Heated air flow is produced when the heating cycle is energized (set thermostat to heat ). 6.4 Continuously-operating ventilation & exhaust fans include readily accessible override controls. Make sure to note the original thermostat settings. If outdoor temp is 55 F

40 Ventilation Air Inlets & Source 7.1 All ventilation air inlets located 10 ft of from known contamination sources (stack, vent, exhaust hood, or vehicle exhaust). Exception: ventilation air inlets in the wall 3 ft. from dryer exhausts and contamination sources exiting through the roof. 7.2 Ventilation air inlets 4 ft. above grade or roof deck in Climate Zones 4-8 and not obstructed at time of inspection. Pay close attention, if ventilation system (supply-only or HRV/ERV) is located in basement.

41 Ventilation Air Inlets & Source 7.3 Ventilation air inlets provided with rodent / insect screen with 0.5 inch mesh. 7.4 Ventilation air comes directly from outdoors and not from adjacent dwelling units, garages, crawlspaces, or attics. If exhaust-only ventilation is used in attached housing, likely can t avoid this but make sure demising wall is sealed as well as possible to compartmentalize (this improves the fire assembly, noise attenuation, and odor transmission)

42 Local Mechanical Exhaust

43 Local Mechanical Exhaust Spec Most bath fans deliver their rated flow at pressure drops of 0.1 inches of water gauge (wg). As a reference, this is roughly the pressure drop created by 50 CFM of flow through a grille, 5 ft of 3-inch flex duct, and a wall cap for the fan...that s it! It's best to use the rated flow at 0.25 wg. to meet the required flow rate, since this is more likely to be the typical static pressure when fans are installed. A typical fan rated at static pressure will operate closer to cfm at 0.25 static pressure. An 80 cfm fan at 0.1 will operate at roughly cfm at 0.25 static pressure.

44 All to Common Exhaust Ducting

45 Local Mechanical Exhaust

46 Observations from the Field Homeowner We have recently been noticing evidence of molding around the bathroom window, resulting from very high humidity level throughout the house (but especially the master bath). This is really a big concern to us because we have been living in the house for just under 2 months, and to have evidence of molding and mustiness reappear is a big issue to us. Here is a perfect example why performance testing is essential to quality control/assurance. Three of the bath fans were restricted in one fashion or another causing blow back into the conditioned space. It is common to see the exhaust fan backdraft damper screwed shut at the connection of the fan housing to the ductwork. Though the exhaust fans were operating, they were not extracting the excess moisture.

47 Ventilation & Exhaust Ratings ENERGY STAR exhaust fan database:

48 Combustion Appliances Combustion Safety Test Procedure for Vented Appliances:

49 Filtration 11.1 At least one MERV 6 or higher filter installed in each ducted mechanical system. A ducted mechanical system is one that has over 10 feet of ductwork. Mini-split systems typically do not have MERV-rated filters available for use and are, therefore, currently exempted All return air and mechanically supplied outdoor air pass through filter prior to conditioning.

50 Filtration 11.3 Filter located and installed so as to facilitate access and regular service by the owner. If the filter is located in the attic, must have a drop-down stairs (no attic hatches) and a permanently installed walkway/platform to get to the filter Filter access panel includes gasket or comparable sealing mechanism and fits snugly against the exposed edge of filter when closed to prevent bypass. Aluminum tape is not acceptable, as the homeowner needs to be able to change filter and re-secure the filter cover.

51 References Designing Forced-Air HVAC Systems: Why Right-Size? Science versus Practicality: Guidelines for Complying with BPI s Technical Standards for the Air Conditioning and Heat Pump Professional: 20Standards_ pdf Ventilating Your Home: HVAC System Quality Installation Rater Checklist Guidebook Slide Deck: ecklist