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
63
of
97
STP Manual
PHONE: 800-221-1522
•
WEBSITE: www.dhtnet.com
09/11/2019
NOTE:
NPT screwed valves are flat-faced to facilitate sealing with the gaskets supplied. Do not
use hemp, tape, or thread-sealing compound. Do not insulate the actuator.
5) Reattach electrical connections. Follow local codes or accepted contractor practices as to
the use and/or type of joint compound or sealer at the connections.
6) Follow the startup procedures to put the unit back online. Carefully check all connections
for any sign of leakage.
4.6
BOILER WATER VFD PUMP OPTION MAINTENANCE
DHT STP Series water heaters are equipped with optional heating source boiler water VFD
pump(s) to assist in the even heating of the water in lieu of Control Valve(s) depending upon
customer preference. If the unit is equipped with this option, the following procedure should be
followed to replace the pump.
NOTE:
Also follow inspection, repair, maintenance and replacement instructions etc. contained in the
pump manufacturer’s documentation shipped with the unit.
VFD 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 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 and control
signal leads to the pump.
d)
Close the isolation valves and drain the boiler water loop.
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 electrical and control signal wiring 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.
