ProtoDesign Inc.
50495 Corporate Dr. Suite 106 Utica MI. 48315
Phone: 586-739-4340
Fax: 586-739-4341
INSTALLATION & OPERATING INSTRUCTIONS FOR THE LW CONTROL
This document should be used by trained personnel as a guide to
install the ProtoDesign Inc. low water control. Follow necessary
wiring practices as defined by the national electric code (NEC).
Installation or selection of equipment should always be
accompanied by trained technical personnel. Reset and probe
wires runs should be separated from high voltage wire runs.
We recommend that secondary (redundant) Low Water Cut-Off
controls be installed on all steam boilers with heat input greater
than 400,000 BTU/hour or operating above 15 psi of steam
pressure. At least two controls should be connected in series with
the burner control circuit to provide safety redundancy protection
should the boiler experience a low water condition. Moreover, at
each annual outage, the low water cut-offs and probes should be
dismantled, inspected, cleaned, and checked for proper
calibration and performance. If used as a LWCO, the control
must be installed in series with all other limit and operating
controls.
SPECIFICATIONS:
Ambient Operation Temp:
0 to 150 deg. F.
Humidity:
85% (non-condensing)
UL Approval:
UL353 limit control
Supply Voltage:
120/220/240/24VAC 50/60 Hz.,10% line
variation.
(220/240VAC for operating control only, non-limit)
Contact Ratings:
SPDT, 10A, 1/3H.P. 120/240VAC. Rated
100,000 cycles rated load.
Power Consumption:
1.5VA
Wiring Terminals:
Optional 11 Pin Plug-In Module socket,
#6-32 screws with pressure clamps. Open board design ¼”
quick connects on high voltage and 3/16” quick connects on low
voltage.
Probe wire distances:
100 feet max. using MTW or THHN
#14 or #16 AWG wire.
Reset terminal wires:
50 feet max. using same wire type
described above.
OPERATION:
TEST FEATURE (Option A)
Allows the LWCO circuit to be
tested. Holding down the reset button for 3 seconds will allow the
LWCO circuit to trip, which simulates the loss of water without
the need to drain the water in the boiler. The control will return to
normal operation once the reset button is pressed a second time or
after a one-minute timeout.
Manual Reset
With a normally closed pushbutton installed across
RESET terminals
TB7
&
TB8
, and after a low water condition, the
relay will remain de-energized until the pushbutton is pressed after
the liquid rises to the level of the probe. With no pushbutton
installed control will be in
Automatic Reset.
Ordering
Option F
allows 85 sec. before manual reset is required, eliminating
nuisance Lockouts.
LWCO -
When the liquid rises to the LOW electrode on terminal
TB6
, the control energizes, changing state of the (LW) load
contacts (LED2 will be lit). The control remains energized until
the liquid level recedes below LOW electrode on terminal
TB6
.
The control then de-energizes, (LED2 will not be lit) returning load
contacts to original state. Unless otherwise specified, there is a
three-second time delay on decreasing level. Liquid must be below
LOW probe on terminal
TB6
for a full three seconds before control
de-energizes.
POWER OUTAGE FEATURE:
The power outage feature is a standard feature for the LW. When
using the manual reset feature, if power interruption occurs when
the probes are in liquid the relay will de-energize. When power is
restored if the liquid is in contact with the probe the relay will
energize without a manual reset. This feature eliminates boiler
lockouts due to power outages when using the reset function.
CSD-1 CODE COMPLIANCE
On Manual Reset units, if the control is in a low- water
condition (water off probe) when there is an interruption of
power, the control will remain in a low-water condition when
power is restored. The reset button will need to be pressed
when the water level is restored to a level above the probe.
PROBE BUILD UP DETECTION
If the resistance of the probe to ground increases to approximately
10k above sensitivity set point the control will turn off and
indicate probe buildup (LED blinking). To clear error, clean or
replace probe. In manual reset mode, probe must be in liquid and
reset button pushed for 30 seconds. In automatic reset mode,
error will clear 30 seconds after probe is in liquid.
Maintenance Schedule
•
Inspect probe annually for scale build-up and clean if necessary. Make certain there is no scale or build-up on the probe or its
white insulator.
•
Replace probe every 10 years. More frequent replacement of the probe is required if it is used in lo cales where significant water
treatment is required, where more frequent cleaning is necessary, or in applications with high make-up water requirements.
•
Replace the low water cut-off every 15 years or after 100,000 cycles on the relay.
