LAARS HEATING SYSTEMS
Page 14
protection device, excessive heat may trip the
thermal switch. This could cause the pump to
shut down intermittently, resulting in rapid
scaling of the heat exchanger.
4.
If designed for floor mounting, install pump
securely on concrete block or pad at least
6 inches (152 mm) above floor level. This will
prevent flooding of the motor when the floor is
washed.
5.
Do not suspend floor mounted pumps from piping.
6.
Plumb piping to avoid putting strain on the pump
casing.
7.
Check the oil level in the pump before starting
the heater. Oil the pump every three months. Oil
pumps located in excessively hot or dusty
locations once a month. Self-lubricating pumps
do not require oiling.
8.
Fill the bearing assembly to the lower level of the
overflow vent.
9.
Add 5 or 6 drops of oil to the front and rear of the
motor. Use 20W non-detergent oil.
2F-10. Storage Tank Installation
1.
Be sure the floor is structurally capable of
supporting the tank when it is filled with water,
and is waterproof.
2.
Place the tank so that manholes, inspection
covers, nameplates and drain valves are
accessible.
3.
Be sure the tank is suitable for the water in the
system. Some water is corrosive and requires a
protected tank. Most tanks are available with
glass, plastic, or galvanized linings.
4.
If the tank is glass-lined, it should be equipped
with a suitable magnesium anode. It is a good
practice to replace the anode when it is
approximately 50 percent used. The factory
warranty on a glass-lined tank may be void if a
satisfactory anode is not in place at the time of a
failure or if it is consumed by cathodic action.
5.
The tank must be lined if a water softener is
installed in the system.
6.
Make sure the tank connections in the heater-tank
circulating loop are the proper size (see Section
2F-5). If tappings are smaller than the
recommended pipe size, a larger pump may be
required. Consult the factory if in doubt.
7.
Install a pipe in the tank drain fitting that goes to
a floor sink, and install a drain valve. If a floor
sink is not available, install a hose bib.
8.
Hot water tanks in an existing installation are
likely to have silt deposits on the bottom.
Therefore, it is important to extend the pump
suction pipe in the tank to a position near the top.
Pipe the return from the heater to the bottom of
the tank.
Flow
Switch
High-Limit
Dry Well
Pressure
Relief Valve
2F-7. Pressure Relief Valve
The pressure relief valve must be installed in the
tapped opening provided in the boiler header with its
outlet piped to a drain or floor sink. Special attention
must be given to relief valve settings in installations
where the boiler is located on the ground floor of a tall
building, or where the operating temperature of the
boiler is above 210°F. In both instances, the static
pressure of the system is elevated, and could cause the
relief valve to leak. Where no special setting of the
relief valve is ordered, the factory will furnish a
125 psi setting.
WARNING
Hot water can scald! Hot water can produce
third degree burns in 6 seconds at 140°F (60°C)
and in 30 seconds at 130°F (54°C).
2F-8. Water Pressure
Keep the water pressure in the system above
30 psi (207 kPa). If the system pressure drops below
30 psi (207 kPa), it could damage the heater through
lack of circulation. If for any reason, the water is
turned off temporarily, to service the equipment for
example, airlock could be a problem when the heater is
turned back on. To eliminate the airlock, open the
pressure relief valve (see Figure 23) and allow the air
to bleed out until water starts to flow. As soon as full
circulation is restored, the trapped air will be released
through the hot water faucets.
Figure 23. Pressure relief valve.
2F-9. Pump Installation (Model VW)
1.
Install a properly sized pump to provide water
circulation between the heater and the storage tank.
2.
Size the pump to avoid an excessive temperature
rise (see Table 4), and to provide the correct flow
for prevailing water hardness conditions.
3.
Install the pump in a cool location. The life of the
pump can be shortened by exposure to excessive
heat. If the pump is equipped with a thermal
