60
B. MPO LWCO
To simplify installation, the MPO LWCO can be
easily installed by removing the LWCO jumper
inside the internal junction box and connecting the
harness into the boiler Molex plug.
Refer to Section II, Paragraph F, Item 2 (of this
manual) for more details.
How to Test
Shut off fuel supply. Lower water level until water
level is BELOW the LWCO. Generate a boiler demand
by turning up thermostat. Boiler should not attempt to
operate. Increase the water level by fi lling the system.
The boiler should attempt to operate once the water
level is above the LWCO.
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I
XIV. LOW WATER CUT-OFF (LWCO) ON HOT WATER BOILERS
Figure A1: Wiring of Aftermarket LWCO
When
A low water cut-off is required to protect a hot water
boiler when any connected heat distributor (radiation)
is installed below the top of the hot water boiler (i.e.
baseboard on the same fl oor level as the boiler). In
addition, some jurisdictions require the use of a LWCO
with every hot water boiler.
Where
The universal location for a LWCO on both gas and oil
hot water boilers is above the boiler, in either the supply
or return piping. The minimum safe water level of a
water boiler is at the uppermost top of the boiler; that
is, it must be full of water to operate safely. Provisions
have been made on the MPO supply manifold for a
LWCO.
What Kind
Typically, in residential applications, a probe type
LWCO is used instead of a fl oat type, due to their
relative costs and the simplicity of piping for a probe
LWCO.
How to Pipe
Attach the LWCO to the 3/4" NPT connection on the
supply manifold. See Figure A2 for more details.
Ideally, manual shutoff valves should be located
above the LWCO and the boiler to allow for servicing.
This will allow probe removal for inspection without
draining the heating system. Many probe LWCO
manufacturers recommend an annual inspection of the
probe.
How to Wire
A. AFTERMARKET
LWCO
The 120 VAC confi guration can be universally
applied to both gas and oil boilers by wiring it in
the line voltage service to the boiler (after the
service switch, if so equipped).
The presence of water in a properly installed
LWCO will cause the normally open contact of the
LWCO to close, thus providing continuity of the
120 VAC service to the boiler.
It is recommended to supply power to the probe
LWCO with the same line voltage boiler service as
shown in Figure A1. See Figure 20 (of this manual)
for more details.
Summary of Contents for MPO Series
Page 6: ...6 Figure 1 MPO 84 Thru MPO 231 Water Boiler ...
Page 22: ...22 Figure 13A Water Boiler Piping for Circulator Zoned Heating System Supply Side Circulator ...
Page 38: ...38 Figure 27 L1 L2 and V1 Head Electrode Positioning and Gun Setting Beckett AFG ...
Page 49: ...49 SERVICE RECORD DATE SERVICE PERFORMED ...
Page 50: ...50 Bare Boiler Assembly ...
Page 52: ...52 Bare Boiler Assembly ...
Page 54: ...54 Jacket Assembly ...
Page 56: ...56 MPO84 Thru MPO231 Water Boilers Trim and Controls ...
Page 58: ...58 Beckett AFG Burner ...
Page 61: ...61 Figure A2 LWCO Location ...
