Product Overview

51
103859-12 - 8/19
MPO-IQ
Installation & Service Manual
A. MAINTENANCE OF LOW WATER CUT-OFF
DEVICES (when installed)
See Instructions provided with Low Water Cut-off
Option Card for Installation Instructions.
WARNING
Probe type low water cut-off devices require
annual inspection and maintenance.
1. PROBE TYPE LOW WATER CUT-OFF
Although these devices are solid state in their
operation, the probe is exposed to possible
contamination in the boiler water and subject to
fouling.
Sometimes the LWCO can be found in the primary
loop of the boiler system. Ideally, shut off valves
have been installed between the loop containing
the LWCO and the rest of the system, to minimize
the amount of system draining.
It is important to physically remove the probe from
the LWCO tapping annually and inspect that probe
for accumulation of scale or sediment.
Follow these steps to inspect, clean and/or replace
the probe:
a. Turn off electric service to the boiler.
b. Drain boiler water to a level below the tapping
for the probe.
c. Disconnect wiring connections between the low
water cut-off control and the probe.
d. Remove the low water cut-off control from the
probe.
DANGER
Assure that the boiler is at zero pressure before
removing the LWCO probe. Do not rely on the
pressure gauge to indicate that the boiler is at
zero pressure. Open the safety valve to relieve
all internal pressure prior to proceeding. Safety
valve discharge piping must be piped such that
the potential for burns is eliminated.
e. Unscrew the probe from the LWCO tapping.
f. Inspect that portion of the probe that is exposed
to the water for a scale or sediment buildup.
g. Light deposits may be removed by wiping the
probe with a damp cloth. Wiping the probe
with a cloth soaked in vinegar will remove more
tenacious lime deposits. The most stubborn
deposits may be removed from the probe by
using a diluted amount, 3 parts of water to 1 part
of phosphoric acid (H
2
PO
4
).
h. Clean the pipe threads of the probe to remove
old, hardened pipe dope and other foreign matter.
i. Apply a moderate amount of good quality pipe
dope to the pipe threads on the probe, leaving the
two end threads bare. Do not use PTFE (Teflon)
tape.
j. Screw the probe into the LWCO tapping.
k. Mount the low water cut-off control on the probe.
l. Reconnect the control to probe wiring.
m. Fill the system with water.
n. Add boiler water treatment compound as needed
(refer to Paragraph B.).
o. Restore electric service to the boiler.
p. Fire burner to bring the water in the boiler to a
boil to drive off free oxygen.
q. WARNING — BEFORE RETURNING BOILER TO
SERVICE: Follow the low water cut-off instructions
provided with Low Water Cut-off Option Card.
B. BOILER AND SYSTEM CLEANING INSTRUCTIONS
FOR TROUBLE FREE OPERATION
1. Filling of Boiler and System — General —-In a hot
water heating system, the boiler and entire system
(other than the expansion tank) must be full of water
for satisfactory operation. Water should be added to
the system until the boiler pressure gauge registers
12 psi. To insure that the system is full, water should
come out of all air vents when opened.
2. Boiling Out of Boiler and System. The oil and grease
which accumulate in a new hot water boiler can be
washed out in the following manner.
a. Ideally, shut off valves have been installed
between the boiler return manifold and the rest
of the system, to minimize the amount of system
draining.
b. Drain the boiler to a level below the relief valve
tapping.
10 Maintenance and Service Instructions
DANGER
Assure that the boiler is at zero pressure before
removing the relief valve. Open the safety valve
to relieve all internal pressure prior to proceeding.
Safety valve discharge piping must be piped
such that the potential for burns is eliminated.
CAUTION
Exercise caution when handling phosphoric acid
and follow the instruction label on its container.
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