B) On/Off Conditions: Btu Requirements - A.O. Smith 710 ASME Service Manual

12-7.(B) ON/OFF conditions: BTU requirements

alculating the ON/OFF conditions of the 710
A. C
【Condition needed to turn the 710 ON】
(T – T ) × GPM × 500 > 14,880
set in
【Condition needed to turn the 710 OFF】
(T – T ) × GPM × 500 <11,900 or T
set in
Where: T
set
B. Calculation example
Set temperature: T
set
【Condition needed to turn the 710 ON】
(120 – T ) × 2.5 × 500 > 14,880
in
【Condition needed to turn the 710 OFF】
(120 - T ) × 2.5 × 500 < 11,900
in
C. ON/OFF table
Set temperature
(˚F)
ON
100
OFF
ON
115
OFF
ON
120
OFF
ON
135
OFF
ON
145
OFF
ON
155
OFF
ON
165
OFF
ON
185
OFF
= T
in set
= Set temperature and T
= 120˚F Flow rate = 2.5 GPM
T < 108.1˚F
in
T
in
The outlet temperature at that moment will be 120˚F
0.5 1.0
40.5 70.2
52.4 76.2
55.5 85.2
67.4 91.2
60.5 90.2 100.2
72.4 96.2 104.1
75.5 105.2 115.2
87.4 111.2 119.1
85.5 115.2 125.2
97.4 121.2 129.1
95.5 125.2 135.2
107.4 131.2 139.1
105.5 135.2 145.2
117.4 141.2 149.1
125.5 155.2 165.2
137.4 161.2 169.1
= Inlet temperature
in
> 110.5˚F
Flow rate (GPM)
1.5 2.0
80.2 85.1
84.1 88.1
95.2 100.1
99.1 103.1
105.1
108.1
120.1
123.1
130.1
133.1
140.1
143.1
150.1
153.1
170.1
173.1
57
CONFIDENTIAL
710 / 710 ASME Service Manual
2.5 3.0
88.1 90.1
90.5 92.1
103.1 105.1
105.5 107.1
108.1 110.1
110.5 112.1
123.1 125.1
125.5 127.1
133.1 135.1
135.5 137.1
143.1 145.1
145.5 147.1
153.1 155.1
155.5 157.1
173.1 175.1
175.5 177.1
Ver. 1.00
3.5 4.0
91.5 92.6
93.2 94.1
106.5 107.6
108.2 109.1
111.5 112.6
113.2 114.1
126.5 127.6
128.2 129.1
136.5 137.6
138.2 139.1
146.5 147.6
148.2 149.1
156.5 157.6
158.2 159.1
176.5 177.6
178.2 179.1