LAARS Mighty Therm VW-PW (Sizes 175-400) - Installation, Operation and Maintenance Instructions - Manual (Page 16)

LAARS Heating Systems
Page 16
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.
2.7.2 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.
2.8 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
2.7 Gas Supply and Piping
2.7.1 General Instructions
Review the following instructions before
continuing the installation.
WARNING
The conversion of heaters from natural gas to
propane gas, or propane to natural, must be done by
a professional service technician. Laars provides kits
and detailed instructions for converting the heater.
Changing burner and/or pilot orifices is prohibited.
The installer must add and sign a gas conversion tag
when the conversion is made.
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 CAN1-B149.1 or .2 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
heaters are normally equipped to operate below a
2000 foot (609 m) altitude. Heaters equipped to
operate at higher altitudes have appropriate
stickers or tags attached.
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 CAN1-B149.1 or .2
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 24 ). Fit the trap with a
threaded cap which can be removed for cleaning.
6. Install a manual gas shutoff valve for service and
safety. Check the local codes.
7. Disconnect the heater and its individual shutoff
valve from the supply gas system during pressure
test of the system at pressures higher than 1/2 psi
(3.4 kPa).
8. Gas supply pressures to the heater are listed in
Table 6.
NOTE: The heater and all other gas appliances
sharing the heater gas supply line must be firing at
maximum capacity to properly measure the inlet
supply pressure. Low gas pressure could indicate
an under-sized gas meter and/or obstructed gas
supply line.
9. Do not exceed the maximum inlet gas pressures
specified. Excessive pressure will result in
damage to the heater's gas controls. The
minimum pressures specified is for gas input
adjustment.
Figure 25. Installation of tempering valve.