A.O. Smith HW 300 Installation & Operation Manual page 35

TWO HW-399's, HW-420's, HW-520's, HW-610's or HW-670's UP-FLOW MODEL
COMMERCIAL BOILER WITH VERTICAL TANK, CER-TEMP 80
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERATURE
AT FIXTURES. SEE TANK TEMPERATURE CONTROL WARNING ON PAGE 11. IF
HIGHER PREHEAT TEMPERATURES ARE NECESSARY TO OBTAIN ADEQUATE
BOOSTER OUTPUT, ADD AN ANTI-SCALD VALVE FOR HOT WATER SUPPLIED
TO FIXTURES.
WIRING - FIGURES 21 to 27 on
USE THIS TABLE FOR CORRECT
PUMP AND WATER PIPE SIZE
Model
Number
HW-300
HW-399
HW-420
HW-520
HW-610/670
* Assumes 50 equivalent feet of piping or less.
IMPORTANT
THE INSTALLATION OF SAFETY FLOW SWITCH AS SHOWN IS
REQUIRED TO PROTECT THE BOILER IN CASE OF WATER SERVICE
INTERRUPTION OR CIRCULATOR FAILURE.
+
GATE VALVES ARE SHOWN FOR SERVICING BOILER. HOWEVER,
LOCAL CODES SHALL GOVERN THEIR USAGE.
*
**
DANGER
pages 28 to 32.
HEATERS SPACED 30" APART
INSTALL IN ACCORDANCE
WITH ALL LOCAL CODES
Minimum
B & G
Pipe Size
Pump
(Inches)
Size
A B
2" 1-1/2" 2"
2" 1-1/2" 2"
2" 1-1/2" 2"
2" 1-1/2" 2"
2-1/2" 1-1/2" 2-1/2"
FIGURE 30.
35
PIPING AND FITTINGS BETWEEN GATE VALVES AND BOILERS
SHOULD BE BRASS OR BRONZE. OTHER PIPING SHOULD
CONFORM TO LOCAL CODES.
PRESSURE RELIEF VALVE RATING SHOULD NOT EXCEED
PRESSURE CAPACITY OF ANY COMPONENT IN THE SYSTEM.
INSTALL THERMOMETER AND PRESSURE RELIEF IN OPENINGS
PROVIDED ON HW-520, HW-610 & HW-670.
*Armstrong
Pump Size
S-35
S-35
S-35
S-35
S-45 2-1/2"