Legend LB 1000 Installation Operation & Maintenance - page 8
8
CIRCULATING PUMP
HOT WATER SUPPLY SYSTEMS, the circulating pump is integral
to the LW models. This pump has been lubricated at the factory,
and future lubrication should be in accordance with the motor
manufacturer’s instructions provided as a supplement to this
manual.
FOR HOT WATER HEATING SYSTEMS-LB MODELS, the circulating
pump is NOT provided and must be obtained and installed in the
field.
NOTE: If a system pump is to be installed on a Legend LB
model, the maximum rating of the pump motor must
not exceed 1 hp.
TANK TEMPERATURE CONTROL
A tank probe is provided with LW models to be used for tank
temperature regulations. The temperature setting for the tank is
set through the display.
Refer to figs. 7, 13, 14 and 16 for connecting the tank probe to the
boiler.
See TEMPERATURE SET POINT ADJUSTMENT PROCEDURE
for further instructions.
FOR HOT WATER SUPPLY SYSTEMS, the boiler is supplied with
a Tank Probe to be field installed in the storage tank. Alternate
methods of temperature control, if desired, must be supplied by
the installer.
A change in water temperature in the storage tank lower than the
Tank Temperature Control setting will cause the sensor to close
its contacts and consequently, energize the boiler.
If the Tank Probe or Temperature Control is out of calibration,
replace it with a new one; do not attempt to fix this control.
NOTE: If you are using an LW model in a hydronic (space heating)
application, do not use the tank probe as a loop temperature
regulation device. The tank probe’s maximum setting is
190°F (88°C). Therefore, 24 VAC connections (red/green wires)
are provided in the rear junction box for an alternate device. The
J33 board jumper must be removed to use a 24 VAC temperature
regulation device (See figures 21 and 22).
LOW WATER CUTOFF (Not Supplied)
If low water protection is required by the authorities having
jurisdiction, a low water cutoff switch should be installed next to
the boiler in the outlet water line as shown in figure 12. The
switch should receive periodic (every six months) inspection to
assure proper operation. A Low Water Cutoff device of the float
type should be flushed every six months.
DRAIN VALVE
A drain valve is factory installed in the heat exchanger manifold.
This will help to drain the heat exchanger.
Additional drain valves must be obtained and installed on each
boiler and tank for draining purposes, see figures 12, 13 and 14.
SAFETY RELIEF VALVE
Your local code authority may have other specific safety relief
valve requirements not covered below.
WARNING
THE PURPOSE OF A SAFETY RELIEF VALVE IS TO AVOID
EXCESSIVE PRESSURE OR TEMPERATURE INTO THE STEAM
RANGE WHICH MAY CAUSE SCALDING AT FIXTURES, TANK
EXPLOSION, SYSTEM OR BOILER DAMAGE.
TO AVOID SCALDING OR WATER DAMAGE, A DRAIN LINE MUST
BE CONNECTED TO A SAFETY RELIEF VALVE TO DIRECT
DISCHARGE TO A SAFE LOCATION. A DRAIN LINE MUST NOT BE
REDUCED FROM THE SIZE OF THE VALVE OUTLET AND IT MUST
NOT CONTAIN ANY VALVES BETWEEN THE BOILER AND THE
RELIEF VALVE OR THE RELIEF VALVE AND THE DRAIN EXIT. IN
ADDITION, THERE SHOULD NOT BE ANY RESTRICTIONS IN A
DRAIN LINE NOR SHOULD IT BE ROUTED THROUGH AREAS
WHERE FREEZING CONDITIONS MIGHT OCCUR. DO NOT THREAD
OR CAP THE DRAIN LINE EXIT. RESTRICTING OR BLOCKING A
DRAIN LINE WILL DEFEAT THE PURPOSE OF THE SAFETY RELIEF
VALVE AND MAY CREATE AN UNSAFE CONDITION. INSTALL A
DRAIN LINE WITH A DOWNWARD SLOPE SUCH THAT IT WILL
NATURALLY DRAIN ITSELF.
If any pressure relief valve is replaced, the replacement valve
must comply with the latest version of the ASME Boiler and
Pressure Vessel Code, Section IV (“HEATING BOILERS”).
Select a relief valve with a discharge rating NOT LESS than the
boiler input, and a set pressure NOT EXCEEDING the working
pressure of any component in the system.
FOR HOT WATER SUPPLY SYSTEMS, the boilers are shipped
with a 125 psi (860 kPa) pressure relief valve that must be installed
in the water outlet as near to the boiler as possible.
This ASME-rated valve has a discharge capacity that exceeds the
maximum boiler input rating and a pressure rating that does not
exceed the maximum working pressure shown on the boiler rating
plate.
In addition, a CSA design-certified and ASME-rated temperature
and pressure (T & P) relief valve must be installed on each and
every water storage tank in the hot water supply system.
FIGURE 7. TANK PROBE INSTALLATION
Encase field-supplied wires
between tank probe and junction
box with 1/2" field supplied
conduit. "Pigtails" of field-
supplied wires should be spliced
to "pigtails" of tank probe and
connected to 24VAC junction box.
This conduit and wiring should be
separate from any other conduit/
wiring to guard against EMI
(electromagnetic interference).