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11. Before operating the heater, test the complete gas
supply system and all connections for leaks using
a soap solution.
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 Natco.
2.
Wire the heater and pump exactly as shown in
the wiring diagram supplied with the heater. See
Figure 25 and 26 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. 18 and 19) to the
heater wiring at points labeled Field Interlock.
Caution
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 24) 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.
Mixing Valve
Hot Water
From Water Heater
or Storage Tank
Figure 24. Installation of tempering valve.
Out —
Mixed Water
For Potable Use
Cold Water
Supply
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