1. Technician’s Guide and Workbook for Zoning Section 2: Zoning Types and Design Decisions

2. Zoning Methods
There are an unlimited number of ways to zone a home! Popular ways include:
More than one single zone HVAC system.
Zone damper systems.
Combinations of different types of HVAC equipment.
Heat transfer based on hydronic, air, or refrigerant based heat exchangers.
Mini-split systems and individual room units.
Cooling or heating only zones.

3. More Than one Single Zone System
Zone 1 2nd Floor
Zone 2 1st Floor
Zone 3 Basement

4. Different Equipment Types
Boiler
Mini-Split
Electric Strip
PTAC
PTAC = Packaged Terminal Air Conditioner

5. Zone Serves More Than One Area
Zone 1 2nd Floor
Zone 2 1st Floor
Zone 2 Basement

6. Zone For Each Floor Level
Zone 1 1st Floor
Zone 2 Basement

7. Heat Transfer: Air, Water, or Refrigerant

8. Zoning Decisions
Zoning decisions are based on many factors. Some are listed below:
Owner Input
Remote Rooms (location)
Life-Style Spaces
Zone by Level
Zone by Exposure
Zone by Construction type

9. Owner Input Master Bedroom In-law Suite Baby’s Room
Game Room and Bar Over Garage
Wine Storage Room

10. Remote Room Locations
Kitchen
Great Room
½ Bath
Laundry
Dining
Garage

11. Life-Style Rooms Master Bedroom Bed 2 Card Room & Bed 3 Bar Bath
Closet
Card Room
&
Bar
Bath
Bed 3

12. Zone For Each Floor Level
Zone 1 2nd Floor
Zone 2 First Floor

13. Zone By Exposure
Zone 2
East Side
Zone 1
West Side

14. Peak Fenestration Loads
Exposure
Month
Hour
Comment
North
Mid-Summer
Relatively Constant
Diffuser radiation gain, conduction peaks in late afternoon.
East
9-11 AM
Low sun angle, 1ft overhang not effective.
South
Fall
1-3 PM
High sun angle, 1ft overhang is effective.
West
5-7 PM
Horizontal
Mid-Day
Use exposure direction for tilted skylights.
Block Load
Normal amount of southern-facing glass.
Large amount of southern-facing glass
Incomplete spaces are easily identified when hourly fenestration loads are graphed for time-of-day.

15. Exposure Load Chart 4-5 PM 4,500 4,000 3,500 3,000 2,500 2,000 1,500
1,000
500
BTUH
Hour of the Day
4-5 PM

16. Zone By Construction Type
Additions or rooms with different types of windows and insulation treated different.

17. Zone For Cooling/Heating Loads
Manual J cooling load is not equal to the Manual J heating load very often.
Manual D duct design is based on the Larger of
the two.
Final airflow provided to the space is often a
compromise between cooling and heating
requirements.

18. Cooling/Heating (C/H)
If Heating CFM = Cooling CFM : C/H = 1
What is the ratio if the cooling CFM is 120 and the heating CFM is 60?
120 ÷ 60 = 2
What is the ratio if the cooling CFM is 60 and the heating CFM is 120?
60 ÷ 120 = 0.5

19. Cooling/Heating (C/H)
If Heating CFM = Cooling CFM : C/H = 1
What is the ratio if the cooling CFM is 88 and the heating CFM is 76?
88 ÷ 76 = 1.158
What is the ratio if the cooling CFM is 76 and the heating CFM is 88?
76 ÷ 88 = 0.864

20. Final Air Balance Affects Temperature
Air Balancing Method Affects Temperature Swing
Room 1 2 3 4 5 6 7 8
Cooling CFM
116
138
119
130
113
151
162 63
Heating CFM 87
111
109
108
126
128
136 75
Average CFM
101.5
124.5
114
119.5
139.5
149 69
XS H-CFM BC
33.3%
24.3%
9.2%
20.4%
-10.3%
18%
19.1%
- 16%
XS C-CFM BH
-25%
-19.6%
-8.4%
-16.9%
11.5%
-15.2%
-16%
19%
XS H-CFM BA
16.7%
12.2%
4.6%
10.2%
-5.2% 9%
9.6%
-8%
XS C-CFM BA
-12.5%
-9.8%
-4.2%
-8.5%
5.8%
-7.6%
9.5%
XS H-CFM BC: Excess heating CFM when the system is balanced for cooling.
XS C-CFM BH: Excess cooling CFM when the system is balanced for heating.
XS H-CFM BA: Excess heating CFM when the system is balanced for average CFM.
XS C-CFM BA: Excess cooling CFM when the system is balanced for average CFM.

21. Air Balance Design Percentages
Air Balancing Method Affects Temperature Swing
Room 1 2 3 4 5 6 7 8
Cooling CFM
116
138
119
130
113
151
162 63
Heating CFM 87
111
109
108
126
128
136 75
Average CFM
101.5
124.5
114
119.5
139.5
149 69
XS H-CFM BC
33.3%
24.3%
9.2%
20.4%
-10.3%
18%
19.1%
- 16%
XS C-CFM BH
-25%
-19.6%
-8.4%
-16.9%
11.5%
-15.2%
-16%
19%
XS H-CFM BA
16.7%
12.2%
4.6%
10.2%
-5.2% 9%
9.6%
-8%
XS C-CFM BA
-12.5%
-9.8%
-4.2%
-8.5%
5.8%
-7.6%
9.5%
XS H-CFM BC: Excess heating CFM when the system is balanced for cooling.
XS C-CFM BH: Excess cooling CFM when the system is balanced for heating.
XS H-CFM BA: Excess heating CFM when the system is balanced for average CFM.
XS C-CFM BA: Excess cooling CFM when the system is balanced for average CFM.

22. Air Balance Design Percentages
Air Balancing Method Affects Temperature Swing
Room 1 2 3 4 5 6 7 8
Cooling CFM
116
138
119
130
113
151
162 63
Heating CFM 87
111
109
108
126
128
136 75
Average CFM
101.5
124.5
114
119.5
139.5
149 69
XS H-CFM BC
33.3%
24.3%
9.2%
20.4%
-10.3%
18%
19.1%
- 16%
XS C-CFM BH
-25%
-19.6%
-8.4%
-16.9%
11.5%
-15.2%
-16%
19%
XS H-CFM BA
16.7%
12.2%
4.6%
10.2%
-5.2% 9%
9.6%
-8%
XS C-CFM BA
-12.5%
-9.8%
-4.2%
-8.5%
5.8%
-7.6%
9.5%
XS H-CFM BC: Excess heating CFM when the system is balanced for cooling.
XS C-CFM BH: Excess cooling CFM when the system is balanced for heating.
XS H-CFM BA: Excess heating CFM when the system is balanced for average CFM.
XS C-CFM BA: Excess cooling CFM when the system is balanced for average CFM.

23. Calculating Percentages
What is 25 percent of 100?
(25 ÷ 100) × 100 = 25 (or 0.25 × 100)
What is 23 percent of 73?
(23 ÷ 100) × 73 = (or 0.23 × 73)
What is 123 percent of 75?
(123 ÷ 100) × 75 = (or 1.23 × 75)
What is 14.2 percent of 376?
(14.2 ÷ 100) × 376 = (or × 376)

24. Calculating XSHcfmBC Percentages
Air Balancing Method Affects Temperature Swing
Room 1 2 3 4 5 6 7 8
Cooling CFM
116
138
119
130
113
151
162 63
Heating CFM 87
111
109
108
126
128
136 75
Average CFM
101.5
124.5
114
119.5
139.5
149 69
XS H-CFM BC
33.3%
24.3%
9.2%
20.4%
-10.3%
18%
19.1%
- 16%
XS C-CFM BH
-25%
-19.6%
-8.4%
-16.9%
11.5%
-15.2%
-16%
19%
XS H-CFM BA
16.7%
12.2%
4.6%
10.2%
-5.2% 9%
9.6%
-8%
XS C-CFM BA
-12.5%
-9.8%
-4.2%
-8.5%
5.8%
-7.6%
9.5%
XS H-CFM BC: Excess heating CFM when the system is balanced for cooling.
XS C-CFM BH: Excess cooling CFM when the system is balanced for heating.
XS H-CFM BA: Excess heating CFM when the system is balanced for average CFM.
XS C-CFM BA: Excess cooling CFM when the system is balanced for average CFM.
[(116 ÷ 87) – 1] × 100 = %

25. Calculating XS CcfmBH Percentages
Air Balancing Method Affects Temperature Swing
Room 1 2 3 4 5 6 7 8
Cooling CFM
116
138
119
130
113
151
162 63
Heating CFM 87
111
109
108
126
128
136 75
Average CFM
101.5
124.5
114
119.5
139.5
149 69
XS H-CFM BC
33.3%
24.3%
9.2%
20.4%
-10.3%
18%
19.1%
- 16%
XS C-CFM BH
-25%
-19.6%
-8.4%
-16.9%
11.5%
-15.2%
-16%
19%
XS H-CFM BA
16.7%
12.2%
4.6%
10.2%
-5.2% 9%
9.6%
-8%
XS C-CFM BA
-12.5%
-9.8%
-4.2%
-8.5%
5.8%
-7.6%
9.5%
XS H-CFM BC: Excess heating CFM when the system is balanced for cooling.
XS C-CFM BH: Excess cooling CFM when the system is balanced for heating.
XS H-CFM BA: Excess heating CFM when the system is balanced for average CFM.
XS C-CFM BA: Excess cooling CFM when the system is balanced for average CFM.
[ (87 ÷ 116) -1] × 100 = -25%

26. Design CFM For Balancing
The actual airflow to be sent to each area/room when the system is balanced is calculated using percentages. That final calculation must be done in the field after the total CFM airflow is established, and the airflow across the heat exchanger is within 10% of the Manual S equipment airflow value.

27. Field Notes
The complaint is simple, and if you start doing airflow balancing in homes that were never balanced, you will hear it often: This room is always too cold in the summer, and then the funniest thing happens, in the winter it is just the opposite, and it is always too hot. The room obviously was not balanced correctly and it is always getting too much airflow.