LAARS Heating Systems
Page 28
Section 8
eleCtrICal ConneCtIonS
8.1 Installation Warnings
CAUTION
The supply voltage to the MagnaTherm unit
must not be disconnected, except for service
or isolation, or unless otherwise instructed by
procedures outlined in this manual. To signal
a call for heat, use the 24V field interlock, as
shown in the wiring diagram.
DO NOT MAKE AND BREAK THE LINE
VOLTAGE TO THE MagnaTherm UNIT TO
SIGNAL A CALL FOR HEAT. A call for heat/
end call for heat MUST be connected to the
field interlock terminals. Some MagnaTherm
components are designed to have constant
voltage during normal operation. If the
MagnaTherm’s supply voltage is toggled as a
call for heat signal, premature failure of these
components may result.
The MagnaTherm unit does not recognize 4mA
as a signal to shut off. If the call for heat is not
connected between the field interlock terminals,
the MagnaTherm will remain in low fire when it
sees 4mA as a modulating signal.
8.2 main Power Connections
Magnatherm is provided with an electrical junction
box in the rear panel for easy connections and all
wires are factory installed between this junction box
and the Main High Voltage Box. The Magnatherm
line is equipped with multiple voltage packages to
adapt to customer needs ranging from 120-600 volts
with single or 3 phase versions. Refer to the rating
plate for appropriate voltage and current ratings. As
a common industry practice, Laars has color coded
the single and three phase wires.
WARNING
The appliance must be electrically grounded in
accordance with the requirements of the authority
having jurisdiction or, in the absence of such
requirements, with the latest edition of the National
Electrical Code, ANSI/NFPA 70, in the U.S. and
with the latest edition of CSA C22.1 Canadian
Electrical Code, Part 1, in Canada. Do not rely
on the gas or water piping to ground the metal
parts of the boiler. Plastic pipe or dielectric unions
may isolate the boiler electrically. Service and
maintenance personnel, who work on or around
the boiler, may be standing on wet floors and
could be electrocuted by an ungrounded boiler.
Electrocution can result in severe injury or death.
Single pole switches, including those of safety
controls and protective devices, must not be wired
in a grounded line.
All electrical connections are made on the terminal
blocks that are located inside the control panel.
Wiring connections are shown in Figure 34.
All internal electrical components have been
prewired. No attempt should be made to connect
electrical wires to any other location except the
terminal blocks.
