HRV and ERV Best Practices. December 18, 2012 Portland Metro Home Builders Association

Transcription

1 HRV and ERV Best Practices December 18, 2012 Portland Metro Home Builders Association

2 The Basics: The X Flow Ports Connected to Inside 72 F 61 F 42 F 32 F Ports Connected to Outside

3 The Single Most Important Installation Detail Make sure exhausts exhaust and intakes intake

4 PORT Stale Air From Inside Fresh Air From Outside Fresh Air To Inside Stale Air To Outside Location Inside Outside Inside Outside Negative House Pressure Positive House Pressure

5 PORT Stale Air From Inside Fresh Air From Outside Fresh Air To Inside Stale Air To Outside Location Outside Outside Inside Inside Negative House Pressure Positive House Pressure

6 PORT Stale Air From Inside Fresh Air From Outside Fresh Air To Inside Stale Air To Outside Location Inside Inside Outside Outside Negative House Pressure Positive House Pressure

7 Where Data Lives

8 IS A HRV OR ERV Latent Recovery/Moisture Transfer (LRMT): Moisture recovered divided by moisture exhausted and corrected for the effects of cross-leakage. LRMT = 0 indicates that moisture was not transferred (net of cross-leakage) from the exhaust airstream to the supply airstream. LRMT = 1 would indicate complete transfer of moisture. LRMT is provided for the Heating Season Performance and the Very Low Temperature Test as an indication of moisture handling characteristics, and may be used to evaluate the moisture transfer ability of the equipment in order to assess the humidification or dehumidification performance of the product at the specified test condition.

9 Some Definitions Net Supply Airflow The gross supply airflow reduced by measured cross-leakage (EATR). This is the actual amount of outside air supplied by the unit and is used only for sizing the equipment for the required ventilation rate. USE THIS RATING FOR VENTILATION SIZING 9

10 Airflow Is Not a Given

11 FAN curves

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13 Flex Like You Have Never Seen

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15 INSTALLATION GUIDELINES ELBOWS Long-Radius Elbows VS Image Source:

16 Account for bends and offsets in the flexible duct. A 90-degree bend has a pressure drop equal to approximately twenty (20) lineal feet of flexible duct. So each 90-degree bend will add twenty (20) equivalent feet to the length used for sizing calculations. A gradual 45-degree bend has a pressure drop equal to about ten (10) lineal feet of flexible duct. A 180-degree offset has a pressure drop equal to about forty (40) lineal feet of flexible duct.

17 Equivalent Length Multipliers 1 for Wire Helix Duct with Compression and Sag Compression Superimposed Sag Negligible 1-inch/Ft 2-inch/Ft 0% to 4% % % % Bagged Coiled Excess length should not be stored in a bag Excess length should not be coiled 1) The recommended standard of care is 4% or less coil compression and negligible sag (2.5 inches sag per 5 feet of span). 2) These multipliers apply to airway sizing tools (friction chart or slide rule) that model the performance of duct that has less than 4% excess length and negligible sag (test stand condition). 3) Compression occurs when excess length is squeezed into a shorter straight line span (see Table A17-3, next page). It is possible to have excess length with negligible compression. 4) The measured span length of flexible duct is the straight line length from entrance to exit (no Group 11 turns), from entrance from a Group 11 turn to the exit. 5) The equivalent length of compressed duct equals the product of the measured span length and a compression-sag multiplier. 6) These equivalent length values do not apply any to other type of duct material. 7) Airway sizes for wire helix duct are read from the Manual D wire helix friction chart, or equivalent; or use the wire helix scale on the ACCA Duct Sizing Slide Rule, or equivalent. 8) Duct fiction charts vary from product to product (depending on construction details). The friction chart or duct slide rule provided by the manufacturer of a particular flexible duct product supersedes the Manual D friction chart and the ACCA Slide Rule. Table A17-2

18 Other Ducting Options

19 Some More Definitions Apparent Sensible Effectiveness (ASE) The measured temperature rise of the supply air stream divided by the difference between the supply temperature ( and exhaust temperature and multiplied by the ratio of mass flow rate of the supply divided by the minimum of the mass flow rate of the supply or exhaust streams. This value is useful principally to predict final delivered air temperature at a given flow rate. The efficiency not including the electrical energy used by the system.

20 Some More Definitions Sensible Recovery Efficiency (SRE) The sensible energy recovered minus the supply fan energy and preheat coil energy, divided by the sensible energy exhausted plus the exhaust fan energy. This calculation corrects for the effects of cross-leakage, purchased energy for fan and controls, as well as defrost systems. This value is used principally to predict and compare energy performance. The efficiency including the energy use of the system 20

21 Why Efficiency Matters Yes, it lowers energy use But it also increases the delivered air temperature This means less air conditioning and higher air delivered air temperatures

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23 Check Wattage of HRV/ERV Manufacturer/Brand Model Type cfm Efficiency (Low Speed) Watts (Low Speed) Annual Fan Energy Use JE Stork Air WHR 950 / CA 350 HRV % Am Aldes 200 SRD HRV 63 70% Broan/Nutone Guardian HRV 200H HRV % Bryant HRVBBLVU1200-A HRV % Bryant ERVBBLHU1200-A ERV % Lennox HRV2-195DDP HRV % Lifebreath 200 MAX HRV 63 70% Lifebreath 300DCS HRV % Renewaire EV200 ERV % Rheem/Ruud 84-HRV-200 HRV % Ultimate Air RecoupAerator 200DX ERV % Trent Metals Ltd. Summeraire SHRV185ST HRV % Venmar HRV5585 Compact HRV % Venmar AVS HRV EKO 1.5 HRV 81 73% Lifebreath 155 ECM HRV 98 63%

24 Higher Efficiency = Higher Delivered Temperatures D e l i v e r e d Delivered Air Temp at Various OATs and ASEs A i r T e m p Apparent Sensible Efficiency 60F 40F 20F 0F Outdoor Air Temp

25 Options for Installation

26 Stand Alone Systems

27 Stale Air from House, Fresh Air to Return

28 Stale Air from Return, Supply Air to Return

29 Stale Air from Return, Fresh Air to Supply

30 Detail for Introducing Fresh Air into a Supply Duct

31 Potential Problems For Air Handler Connected Systems Increased energy use To avoid cross commination of air streams, the furnace fan should run whenever the DHP is in exchanging air: 400 watts X 24hr/day X365 days/year =3504 KWh/year Could be up to 3000 kwh a year in energy use; that s That s ignoring any extra duct losses if the duct are outside

32 Potential Problems For Air Handler Connected Systems Overcoming large negative and positive pressures in the return and supply Do the pressures generated by big furnace fan ever overpower the pressure generated by the small ERV/HRV fan?

33 Potential Problems For Air Handler Connected Systems Balancing With an increase of multi-staged or modulating equipment that have ECMs, what fan speed do you balance at? How do you know what fan speed you re at? As filters and coils get dirty, the pressures in the duct change

34 Noise: Keep it Quiet Stupid

35 Separate Exhaust from Intake

36 ASHRAE

37 Basic Formula for Continuous Ventilation Rate Required CFM for continuous ventilation CFM =.01 X Floor area =7.5 X (#bedrooms +1) Example: 2500 square foot house with 2 bedrooms.01 X X(2+1)= = 47.5 cfm

38 Ventilation Air Requirements, CFM Based on: ASHRAE 62.2, Table 4.1a (I-P)

39 Non-Continuous Ventilation

40 Non-Continuous Run Time Multipliers Based on ASHRAE 62.2, Table 4.2 This chart estimates the required cfm need for non-continuous ventilation systems

41 Room Airflows Supply to bedrooms and main body 10 cfm per person 10 cfm small bedroom 20 cfm master bedroom 20 cfm main body Exhaust from bathrooms, kitchen (not near the stove) ASHRAE 62.2 allows 20 cfm continuous instead of 50 cfm bath fan (saves some money)

42 Don t Use Wall Hoods with Gravity Dampers as Fresh Air Intakes

43 Setting the Controls Controls need to be up to meet ASHRAE 62.2

44 Defrost Options Recirculation of indoor-air: No ventilation when this occurs! Exhaust only, no heat recovery Electric heating element Geo-thermal or pumped glycol loop

45 Defrost Defrost Logic: Logic changes between systems Temp only Change in efficiency How long does it last?

46 Geo Thermal Booster Can help heat the air in winter and cool air in summer; also works as defrost

47 Other Types of HRVS Lunas reversing heat recovery Hrvs Panasonic Spot ERN

48 Balancing Aldes Iaq source supply

49 Balancing: Why it s Important Efficiency: The rated efficiency is given at specific set of conditions. If unbalanced, the rated efficiency is unknown. Building pressure Exhaust > than supply = negative building pressures Supply > than exhaust = positive building pressures

50 Best Practices: System Selection High apparent sensible efficiency will produce higher delivered air temperatures High sensible recovery efficiency will produce the lowest energy use

51 Best Practices: Location Of Unit 1. Easily accessible 2. Inside the conditioned space venmar

52 Best Practices: Distribution 1. Stand alone is the best 2. Stale from house, fresh air to return side of air handler o o o AH static pressures work with HRV/ERN not against AH and HRV/ERV do not have to be tied together When AH is off fresh air will into the duct work, some might exit the return, but who cares?

53 Best Practices: Duct Work 1. Size using a low friction rate (.06) or manufactures recommendation 2. Keep inside the condition space 3. Don t do stupid stuff with flex duct 4. Minimize duct length through central location 5. Use mastic, seal them airtight

54 Best Practices: Wall Hoods 1. Maintain separation of exhaust and intake units hoods 2. Don t use gravity dampers on intakes 3. Place where the homeowner can clean them 4. Caulk insect screen in place if it Venmar has gaps

55 Best Practice: Commissioning Balance as per manufacturer s recommendation Measure airflow per room Double-check that intakes intake and exhausts exhaust Set controller to meet ASHRAE 62.2 Record all readings and post on unit

56 Best Practice: Commissioning Compare temperatures between incoming and outgoing air. Does it match efficiency rating? aldes

57 Best Practices: Homeowner Education Leave all manuals, especially ones concerning setting the controller Emphasize filter and screen cleaning Document all testing and commissioning Sell a maintenance contract Emphasize the importance of ventilation

58 THANK YOU QUESTIONS? Contact us to learn more NorthwestENERGYSTAR.com P: E: