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Zoning Application. Zoning Application. Agenda Application Overview --Benefits & Challenges with Zoning HVAC System Designs Conventional Vs Zoning Excess Air --Defining --Management Strategies. Zoning Application.

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Zoning Application


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    1. Zoning Application

    2. Zoning Application Agenda Application Overview --Benefits & Challenges with Zoning HVAC System Designs Conventional Vs Zoning Excess Air --Defining --Management Strategies

    3. Zoning Application Zoning is the intentional restriction of capacity (air flow) into a specific zone. Why Zoning and how can a customer benefit from zoning? Have you come across a zoning system that did not provide these benefits?

    4. Zoning Application Air Conditioning Contractors of America (ACCA) provides standards in designing HVAC system. There are standards for conventional systems and standards for zoning systems. Which manuals are mandatory? Manual J8 is required for the proper application & design of zoning systems.

    5. Zone Heat Gain Sensible Heat Gain Graph of Manual J8 Software will show “Powered by Manual J” BTU’s The yellow line represents a 30% buffer zone. Room temperature swings may be extreme if hourly load conditions exceed this buffer limit. The lower green line shows the average sensible heat gain. This is used to size the HVAC system The red line represents the actual hourly heat gain. Time

    6. Zone Heat Gain BTU’s Some applications will have extreme excursions. This is especially true for homes with large glass loads or condominiums (small interior loads with only one external wall). If zoning is applied, the duct size must be sized upon the red line peak excursion. Time

    7. Zoning Application The fundamentals remain the same: An accurate heat load calculation & proper duct design is critical. Zoning should never be applied to oversized systems or undersized ducting. The HVAC system is sized on _________ ________________ The duct system is sized on _________ ________________

    8. Zoning Application The Basics Always start with a “common sense” approach when applying zoning. There are several tools out there to assist with calculations, but always stay focus on the obvious: • Rooms that are open to each other should be in the same zone. • With multiple story homes, each floor should be a zone. • Unique rooms (detached rooms or rooms with large glass loads) should be individually zoned.

    9. Zoning Application The Basics • Each zone must have a dedicated return path. • Each sensor must be in the air path of the zone it controls. • Never apply more zones than the equipment can handle. What happens with only the smallest zone calling.

    10. Zoning Application Daily Solar Load Shifts Room grouping from ACCA Manual RS Daily solar shifts

    11. Guest Room 2 Guest Room 1 Living Room N W E Add 1 Ad 2 Add 3 Office Master Bed S Kitchen Dining

    12. Zoning Application Seasonal Load Shifts Room grouping from ACCA Manual RS Seasonal load shifts and the 15% rule.

    13. Guest room Guest room Living room 73% C/H Ratio 63% C/H Ratio Add 1 Ad 2 Add 3 109% C/H Ratio 61% C/H Ratio Office Master Bed Dining Kitchen

    14. Zoning Application Excess Air What happens to a system when air flow is restricted? How can this reduction in air flow be managed?

    15. Zoning Application Excess Air Management Strategies • Bypass • Dump • Variable Speed Air • Flow Reduction • Multi Capacity Systems • Relief • Over Blow Excess air must be managed based on worst case conditions!

    16. Zoning Application DST Thermal Limits

    17. Which is the smallest zone in heating? How much excess air must be managed? Which is the smallest zone in cooling? How much excess air must be managed?

    18. Zoning Application Understanding Bypass Supply Air Manual D informs us how to size the ducting to each zone. But how do I size a bypass duct? Return Air Mixed Air

    19. Zoning Application Calculating Bypass Supply Air Turn on the system with the smallest zone calling and the bypass damper wide open. Obtain two dry bulb temperature readings: Temp split from return & bypass air. Temp split from return & mixed air. Bypass Air Reading Return Air Mixed Air Mixed Air Reading Return Air Reading

    20. Zoning Application Understanding Bypass Taken from the install guide of a popular zoning system. Take a look at what happens with this much bypass. This is 75% bypass Return Air Mixed Air

    21. Temp splits with 36% bypass on a 4-ton cooling system.

    22. Temp splits with 64% bypass on a 4-ton cooling system.

    23. 43% bypass on 80K 4-ton drive furnace Temp Rise 30⁰ - 60⁰

    24. 18% bypass on 80K 4-ton drive furnace

    25. Zoning Application What are the main advantages of Bypass? What are the main disadvantages of Bypass?

    26. Zoning Application $$$ Savings on Energy Bills? Will zoning deliver energy savings? “The benefit of a set-up / set-back schedule depends on the cycle time. Long periods (days or weeks) of set-up / setback save energy. Short set-up / set-back periods (less than a day, maybe less than 16 hours) saves less energy, or may increase energy use.” ACCA Preliminary Manual Zr

    27. Zoning Application $$$ Savings on Energy Bills? 4-ton AC system 10.6 EER 9.7 EER 8.5 EER

    28. Zoning Application Variable Speed Air Flow Reduction A variable speed indoor unit can reduce air flow up to 30% in compressor only operation. This creates similar results as bypass but with some energy savings. Air flow reduction is the preferred method over bypass, but is not incorporated with gas furnaces or when resistant heat is in use. Air flow reduction and bypass may not be utilized at the same time.

    29. 1985 CFM at 0.7 static consumes 824 watts. A 30% air flow reduction will deliver1389 CFM. 1383 CFM = 396 Watts at 0.7 static. Even if static remains constant as dampers close, blower reduction assists with energy savings.

    30. Zoning Application Multi Capacity Systems Can multi capacity systems assist with zoning?

    31. Zoning Application Over blow Over blow makes the assumption that air will be redirected through the ducting as dampers close.

    32. Zoning Application Over blow This duct system is moving 600 FPM. How much air flow will this 8 inch duct deliver__________? Static pressure & velocity rates will increase as dampers close. How much air will this 8 inch duct deliver at 900 FPM? Can you count on over blow with a high static duct system?

    33. Zoning Application Setting Duct Size -- Weight What are some advantages of an oversized duct system with zoning? What are some disadvantages of an oversized duct system? Should the zone control system know the duct size to each zone? Why? Auto Zone Weighting or Manual Set up

    34. Zoning Application Setting Duct Size -- Weight A main duct is defined as any damper that controls more than one supply terminal.

    35. Zoning Application Time to add it all up • Time to calculate a basic two zone single stage system with psc motor. But first, how will I obtain the following information. • The required air for each zone • The amount of excess air that must be managed • The maximum allowable bypass • The amount of over blow (if any) • The remaining amount of excess air

    36. 14” 12” 1000 CFM @ 900 feet per minute 700 CFM @ 900 feet per minute

    37. Blower set to deliver 1600 CFM. The bedroom is the only zone calling and requires 36% of this air flow. The bedroom requires ________ CFM. Due to the limitations of the furnace, the maximum bypass is 18% which is ________ CFM. I need to find a home for the remaining ________ CFM. Cooling Mode Factor in over blow. The 12 inch duct can handle 700 CFM at 900 FPM (700 – ______required by bedroom = ______ CFM of over blow). 1600 CFM – 700 into the zone – ______bypass = _______CFM (_____%) of excess air. How can we manage this excess air? 12” 700 CFM @ 900 feet per minute

    38. Blower set to deliver 1600 CFM. The living room zone is the only zone calling and requires 64% of this air flow. The living room requires ________ CFM. Due to the limitations of the furnace, the maximum bypass is 18% which is ________ CFM. I need to find a home for the remaining ________ CFM. Cooling Mode Factor in over blow. The 14 inch duct can handle 1000 CFM at 900 FPM (1000 – ______required by living room = ______ CFM of over blow). 1600 CFM – 1000 into the zone ______bypass = _______CFM (_____%) of excess air. How can we manage this excess air? 14” 1000 CFM @ 900 feet per minute

    39. Blower set to deliver 1275 CFM. The bedroom is the only zone calling and requires 43% of this air flow. The bedroom requires ________ CFM. Due to the limitations of the furnace, the maximum bypass is 18% which is ________ CFM. I need to find a home for the remaining ________ CFM. Heating Mode Factor in over blow. The 12 inch duct can handle 700 CFM at 900 FPM (700 – ______required by bedroom = ______ CFM of over blow). 1275 CFM – 700 into the zone – ______bypass = _______CFM (_____%) of excess air. How can we manage this excess air? 12” 700 CFM @ 900 feet per minute

    40. Blower set to deliver 1275 CFM. The living room zone is the only zone calling and requires 57% of this air flow. The living room requires ________ CFM. Due to the limitations of the furnace, the maximum bypass is 18% which is ________ CFM. I need to find a home for the remaining ________ CFM. Heating Mode Factor in over blow. The 14 inch duct can handle 1000 CFM at 900 FPM (1000 – ______required by living room = ______ CFM of over blow). 1275 CFM – 1000 into the zone – ______bypass = _______CFM (_____%) of excess air. How can we manage this excess air? 14” 1000 CFM @ 900 feet per minute

    41. Cooling mode bedroom calling. Living room damper stop must be set to manage 612 CFM. 38% relief. Cooling mode bedroom calling. 576 CFM is required based on conventional system design . 412 CFM is managed through over blow & bypass. Cooling mode living room calling. 1024 CFM is required based on conventional system design. 288 CFM is managed by bypass. Cooling mode living room calling. Bedroom damper stop must be set to manage 312 CFM. 20% relief. 14” 12” 1000 CFM @ 900 feet per minute 700 CFM @ 900 feet per minute

    42. Heating mode bedroom calling. Living room damper stop must be set to manage 345 CFM. 27% relief. Heating mode bedroom calling. 548 CFM is required based on conventional system design . 382 CFM is managed through over blow & bypass. Heating mode living room calling. Bedroom damper stop must be set to manage 45 CFM. 4% relief. Heating mode living room calling. 727 CFM is required based on conventional system design. 503 CFM is managed by over blow & bypass. 12” 14” 700 CFM @ 900 feet per minute 1000 CFM @ 900 feet per minute

    43. Living Room Damper Bedroom Damper Damper relief must be set for worst case conditions which is 20% for the cooling mode (only 4% required in heating mode). The zone will receive 16% more air than is required during the heating mode. Damper relief must be set for worst case conditions which is 38% for the cooling mode (only 27% required in heating mode). The zone will receive 11% more air than is required during the heating mode. Would a variable speed motor help? Why? Would multi capacity systems help? Why 14” 12” 1000 CFM @ 900 feet per minute 700CFM @ 900 feet per minute

    44. Would oversizing the duct system help? Moving from a 14 to a 16 inch duct allows for an additional 500 CFM of over blow. This reduces the bedroom cooling damper stop from 20% to 0%. It reduces the bedroom heating damper stop from 4% to 0%. Moving from a 12 to a 14 inch duct allows for an additional 300 CFM of over blow. This reduces the living room cooling damper stop from 38% to 20%. It reduces the living room heating damper stop from 27% to 4%. What are the risks of oversizing ducting? 16” 14” 1500 CFM @ 900 feet per minute 1000 CFM @ 900 feet per minute

    45. What happens as the number of zones increases? 8” 10” 250 CFM @ 900 feet per minute 410 CFM @ 900 feet per minute How well will a single stage system work on 4 zone application? 12” 8” 700 CFM @ 900 feet per minute 250 CFM @ 900 feet per minute

    46. What happens in a home with different zones at different temperatures? Heating Cooling 8” 10” 68⁰ 77⁰ 250 CFM @ 900 feet per minute 410 CFM @ 900 feet per minute Cooling Cooling 12” 8” 75⁰ 84⁰ 700 CFM @ 900 feet per minute 250 CFM @ 900 feet per minute

    47. Zoning Application What are the chances any dealer / designer is going to go through all these steps? How many zoning systems are working properly?

    48. Zoning Application Bypass is a way to manage excess air. The downfall is it’s extremely difficult to configure and impossible to maintain consistency. • The Comfortlink II / AccuLink zone system has the ability to manage excess air based on static pressure and discharge air temperature. • System configuration is simplified. • System performance is improved. • Homeowner comfort is maximized.