Quality install testing procedures for forced air systems
-
Upload
center-for-energy-and-environment -
Category
Documents
-
view
341 -
download
0
Transcript of Quality install testing procedures for forced air systems
Quality Install Testing Procedures for Forced Air
Systems
Quality Installation: Outcomes
• Installation practices have links to • Comfort• Humidity Levels (dehumidification)• Reduced Utility Consumption • Reduced Utility Consumption • Indoor Air Quality
Why Test?
• SEER reduced when airflow not correct• High Static = more power draw on ECMs• ECMs start to draw more power at .8” wc• Must know system performance to • Must know system performance to
consider ECM upgrade
Why Test?
• Coils, filters, ductwork (flexible lines worst), registers all add to Total External Static Pressure (TESP)
• High static pressure makes more noise• High static pressure makes more noise• Flow directly effects comfort• No test is just a guess
Two Main Tests
• Total External Static Pressure• Air Flow CFM
What is Rated TESP?
What is TESP?
All components add resistance. Too much
restricts flow.
Testing TESPStatic Pressure Tube and Manometer
Testing TESPPitot Tube and Manometer
Testing TESP (Heat Only)
• TESP = top of heat exchanger to bottom of blower (after filter)
• Pressure Drop = • Pressure Drop = change over a distance (AC coil, filter, etc.
• Check rating (includes coil? Filter?)
Testing TESP Rooftop units
• TESP = Supply and return
• Pressure Drop = change over a distance change over a distance (AC coil, filter, etc.
• Rated TESP, coil included in package units.
Testing TESP
• TESP = Add two numbers together
• Pressure Drop = subtract numbers subtract numbers (ignore ± sign)
TESP Results
• Think Golf and Blood Pressure• Lower is better• High numbers indicate a problem• And a need for…more practice, exercise • And a need for…more practice, exercise
and tweaking the system
Example w/no and dirty filter
• 10 After coil • 4 Before Filter• 10 After Filter• 70 Before Coil
• 6 After coil • 4 Before Filter• 52 After Filter• 43 Before Coil • 70 Before Coil
• **TESP = 80• **∆P Coil = 62• ∆P Filter = 2
• 43 Before Coil • ***TESP total = 95• ∆P Coil = 38• **∆P Filter = 48
Testing Air Flow (CFM)
• Static Pressure affects air flow• Air flow determines efficiency• Need air flow to set refrigerant• Need 400~ cfm per ton of cooling• Need 400~ cfm per ton of cooling• Need to know # of tons
Testing Air FlowTrue Flow Meter®
True Flow Meter®
• Energy Conservatory, MN Manufacturer• Advantages: very accurate, fairly easy to
set up• Disadvantages: Equipment can be • Disadvantages: Equipment can be
expensive, needs filter slot that fits plates, can be effected by poor duct design
True Flow Meter®
• Install in filter slot• Meter automatically averages flow rates• Needs manometer (pressure gauge)
Testing Air FlowHot Wire or Mini-Vane Anenometer
Hot Wire or Mini Vane
• Advantages: Fast and east to use, accurate (when compared to True Flow meter)
• Disadvantages: Cost, need linear section • Disadvantages: Cost, need linear section of duct
Hot Wire or Mini Vane
• Drill holes in duct• Take readings• Meter automatically calculates flow rates
Testing Air FlowHotwire or Mini-Vane Anenometer
TESP
• Advantages: Low cost, Quick and easy (if table available), good for troubleshooting
• Disadvantages: Fan tables sometimes not available (can use generic), duct available (can use generic), duct configurations may cause turbulence
TESP
• Take readings• Know fan speed setting, rated TESP• Match readings off fan table to find CFM
Fan Table
Potential Problems Found
Restrictive filter (up to 50% drop in flow) Restrictive designer registers
Potential Problems Found
Dirty AC Coils Owner did not know it existed
Potential Problems Found
Dirty Fan Blades Leaky Ductwork
Possible Solutions
• Less restrictive filters• Regular filter changes, maintenance • Curved ductwork, turning vanes• Registers with free air • Registers with free air • Smooth ductwork, not flex duct• Proper sizing of ductwork• Sealing ductwork
Challenges
• Additional testing often means more cost• Additions to ductwork can add cost to
proposal• “Low Bid” vs. most responsible bid• “Low Bid” vs. most responsible bid• Customer education• Contractor education
Benefits
• Energy Savings (that is expected and predicted)
• Increased Comfort• Better customer service• Better customer service
Thank You
Bruce Stahlberg, CEMAffordable Energy Solutions, Inc.
Minneapolis, MN Minneapolis, MN