LAARS HEATING SYSTEMS
Page 16
damage to the heater's gas controls. The
minimum pressures specified is for gas input
adjustment.
10.
The correct burner manifold gas pressure is
stamped on the rating plate. The regulator on the
gas valve is preset at the factory, and does not
normally need adjustment.
11.
Before operating the heater, test the complete gas
supply system and all connections for leaks using
a soap solution.
Caution
Since some leak test solutions (including soap and
water) may cause corrosion or stress cracking,
rinse the piping with water after testing.
2G-2. Special Precautions
for Propane Gas
Liquefied petroleum (LP) gas is heavier than air.
Therefore, do not install heaters using LP gas in a pit
or locations where gas might collect. Locate heaters a
safe distance from LP gas storage and filling
equipment. Consult local codes and fire protection
authorities about specific installation restrictions.
2H. Electrical Wiring
WARNING
Electrically ground the heater in accordance with
the latest edition of the National Electrical Code,
ANSI/NFPA 70. In Canada, use C22.1. Do not rely
on the gas or water piping to ground the metal parts
of the heater. Often, plastic pipe or dielectric unions
isolate the heater electrically. Service and
maintenance personnel who work on or around the
heater may be standing on wet floors and could be
electrocuted by an underground heater.
1.
Check heater wiring and pump for correct
voltage, frequency, and phase. Check to make
sure heater is wired for 120 volts alternating
current (VAC). If 240 VAC, contact local factory
representative or Laars.
2.
Wire the heater and pump exactly as shown in the
wiring diagram supplied with the heater. See
Figure 26 and 27 for a typical example of a
wiring diagram.
3.
Electrically interlock the pump and heater so the
heater cannot come on unless the pump is
running.
4.
Connect all field-installed devices (draft
switches, relays, timers, outdoor temperature
reset devices, etc.) (see Figs. 19 and 20) to the
heater wiring at points labeled Field Interlock.
2I. Combined Space Heating/Potable
Water Heating Systems
2I-1. Combined Space Heating
The VW and PW heaters are not to be used as a
source of heat for a combined space heating system.
2I-2. Potable Water Heating
Do not use water piping, fittings, valves, pumps,
and any other components which are not compatible
with potable water.
Do not connect the heater, which will be used to
supply potable water, to any heating system or
components previously used with a non-potable water
heating system.
Do not add heater treatment or any chemicals to
the heating system piping, since the piping contains
water for potable use.
Do not use solder containing lead in the potable
water lines.
If the space heating system requires water
temperatures greater than the water temperature for
potable hot water use, a tempering valve (see
Figure 25) or other means should be installed in the
potable hot water supply line to limit the risk of scald
injury.
Some jurisdictions may require a backflow
preventer in the cold water line. In such cases, the
temperature and pressure relief valve may discharge
water due to expansion. A diaphragm type expansion
tank will normally eliminate this condition. Follow the
manufacturer's instructions for installation of the
expansion tank.
Figure 25. Installation of tempering valve.
Out —
Mixed Water
For Potable Use
Hot Water
From Water Heater
or Storage Tank
Mixing Valve
Cold Water
Supply
