LAARS Mighty Therm LO-NOx VW (Sizes 250/400) - Installation, Operation and Maintenance Instructions - Manual (Page 13)

Mighty Therm LO-NOx Volume Water Heater Page 13
2.6.4). 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.
Note: Incorrect installation can cause rapid
failure of water tanks due to electrolysis. Tanks must
be installed with dielectric connections to electrically
isolate the tank from stray current. Note that use of
brass or bronze connectors does not replace the need
for dielectric connections.
2.6.9 Thermal Circulation of Hot Water
in Cold Water Supply Lines
Under certain circumstances, thermal circulation
will occur in the cold water pipe supplying the water to
the heating system. This happens in a multi-story
building when the cold water pipe rises from its
connection to the system. To correct the problem, a
check valve in the cold water line supplying the heater
will prevent thermal circulation, and a small expansion
tank will permit heated water to expand without
popping off the relief valve.
2.7 Gas Supply and Piping
(Natural Gas Only)
2.7.1 General Instructions
Review the following instructions before
continuing the installation.
1.
Gas piping installation must be in accordance
with the latest edition of ANSI Z223.1. In
Canada, the installation must be in accordance
with CSA-B149.1 and all local codes that apply.
2. Check the rating plate to make sure the heater is
fitted for the type of gas being used. Laars LO-
NOx heaters are normally equipped to operate
with natural gas below a 2000 foot (609 m)
altitude.
3. If a gas pressure regulator is required, the
installation must be in accordance with the latest
edition of ANSI Z223. In Canada, the installation
must be in accordance with CSA-B149.1 and all
local codes that apply.
4. The figures in Table 5 should be used to size the
gas piping from the gas meter to the heater.
5. Install a sediment trap (drip leg) ahead of the gas
controls (see Figure 25). Fit the trap with a
threaded cap which can be removed for cleaning.
valve is directed to an open drain and protected
from freezing.
2. Install a properly sized thermal expansion tank
on the cold water supply line.
2.6.6 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. 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).
2.6.7 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 22) 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.
2.6.8 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
OUT OF
PRODUCTION