A.O. Smith BTR(C)120 THRU 500A Installation Operation & Maintenance page 18

INSTALLATION DIAGRAMS-SIDE INLET/OUTLET USAGE
A listed temperature and pressure relief valve of adequate
capacity is installed on the heater. The locations shown in the
installation diagrams on the following pages are typical.
TWO TEMPERATURE - TWO HEATERS, ONE PRE-HEATER/ONE - BOOSTER HEATER
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE
TEMPERATURE AT FIXTURES. SEE WATER TEMPERATURE CONTROL
WARNING ON PAGE 27. IF HIGHER PREHEAT TEMPERATURES ARE
NECESSARY TO OBTAIN ADEQUATE BOOSTER OUTPUT, ADD AN ANTI-
SCALD VALVE FOR HOT WATER SUPPLIED TO FIXTURES.
CIRCULATING RETURN LINE CONNECTIONS
- FROM FIXTURE LOOP, IF USED, CONNECT TO PREHEATER INLET.
- FROM BOOSTED TEMPERATURE LOOP, IF USED CONNECT TO
BOOSTER INLET.
†AVALAIBLE FROM A.O. SMITH.
*PIPE RELIEF VALVE TO OPEN DRAIN.
INSTALL IN ACCORDANCE WITH LOCAL CODES.
WITH OR WITHOUT BUILDING RECIRCULATION
DANGER
The discharge opening of the temperature and pressure relief
valve must be piped to an open drain and should not be subject
to freezing conditions. DO NOT REDUCE, BLOCK OR PLUG
THE DISCHARGE OPENING OF THE VALVE.
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