Honeywell Design and Application User Manual

Section 1 - Ventilation
Honeywell Economizers 63-8594-02 12
Outside Air Percentage Chart
This chart can also be used for measuring the
percentage of outside air on an air handler.
The same three temperatures are measured
per the formulas on the preceding page. Lines
are drawn on the chart using a ruler. As with
the formulas this chart is most effective if there
is at least a 10 degree F difference between
the return and outside air. This will typically
require either a warm or cold day rather than
moderate weather. It is more accurate to
measure outside air percentage on a day
when the outside temperature is 10°F (-12°C)
rather than on a day when it is 70°F (21°C). If
the temperature difference between the return
and outside air is only a few degrees, a small
error in measurements can alter the results by
as much as 50% using this method. If the
temperature difference is 40 or 50°F (22 or
28°C) small errors in measurement do not
substantially affect the results of the
calculations.
OUTSIDE AIR TEMPERATURE
MIXED and RETURN AIR TEMPERATURES
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
%
O
U
T
S
I
D
E
A
I
R
%
O
U
T
S
I
D
E
A
I
R
49 C
120 F
43
110
38
100
32
90
27
80
21
70
16
60
10
50
4
40
-1
30
-7
20
-12
10
-18
0
-23
-10
-29 C
-20 F
120 F
49 C
110
43
100
38
90
32
80
27
70
21
60
16
50
10
40
4
30
-1
20
-7
10
-12
0
-18
-10
-23
-20 F
-29 C
M25274A

Honeywell Design and Application Specifications

General

Brand	Honeywell
Model	Design and Application
Category	Controller
Language	English