STP SERIES Install, Operation, and Maintenance Manual
SECTION 4: MAINTENANCE
Rev-1
Diversified Heat Transfer, Inc.
•
439 Main Road, Route 202
•
Towaco, New Jersey 07082
Page
55
of
97
STP Manual
PHONE: 800-221-1522
•
WEBSITE: www.dhtnet.com
09/11/2019
4.1 CIRCULATING PUMP MAINTENANCE
DHT STP Series water heaters are equipped with circulating pump(s) to assist in the even
heating of the water. If the unit is equipped with a circulating pump, the following procedure
should be followed to replace the pump.
CIRCULATING PUMP INSPECTION AND REPLACEMENT
INSTRUCTIONS
a) Take the unit offline (Steps: 1 through 5 of the shutdown procedure, Sec. 3.9) before
attempting to service the circulating pump.
WARNING!
TURN OFF/DISCONNECT ALL ELECTRIC POWER BEFORE ATTEMPTING ANY
MAINTENANCE PROCEDURE.
b) Test the pump according to manufacturer’s instructions supplied with the test unit. If
found to be defective or worn, replace the pump per the following steps:
c) After assuring that the power has been turned off, disconnect the electric leads to the
circulating pump.
d) Drain the unit by opening the drain valves (See Figures 3-1a and 3-1b).
e) Break the flanged joint between the pump and the inlet and outlet piping.
f) Remove the pump.
g) Reconnect the pump to the inlet and outlet piping. Follow recommendations contained
in the manufacturer’s documentation, local codes, or accepted contractor practices as
to the use and/or type of joint compounds or sealer at the connections.
h) Reconnect the electric leads to the pump (reference wiring diagram provided with the
unit to assure proper wiring).
i) Follow the startup procedures (Section 3.8) to put the unit back online. Carefully check
all connections for any sign of leakage.
WARNING!
DO NOT RUN THE PUMP WITHOUT WATER AND FAILURE TO DO SO CAN CAUSE
DAMAGE TO THE PUMP.
NOTE:
Follow inspection, repair, maintenance and replacement instructions etc. contained in the pump
manufacturer’s documentation shipped with the unit.
