L.B. White Therma Grow HW120 Manuel Du Propriétaire page 14

14
Therma Grow™ Greenhouse Heaters
2. To Connect the Direct Wired Thermostat Kit to the
Control Box on the Heater:
a. The installation and wiring of a thermostat must be
done by an electrician or someone properly qualified.
b. The thermostat may use 18 gauge, 2 wire cord to
handle the low voltage being supplied to the thermo-
stat from the transformer.
c. Follow all instructions provided with the thermostat kit.
d. The heater must be tested for proper operation after
the thermostat has been connected.
Two Stage Heater
This heater features a two-stage gas control valve and a
heat - ventilation switch. These features expand the
capability of the heater to cost effectively maintain
temperature and likewise enhance air circulation in the
greenhouse when heating is not required.
The two-stage gas control valve provides the ability to more
closely match heat to need - starting at the first stage
(minimum or mid-rating position) and only moving to
second stage (maximum or full rating position) if needed to
satisfy the temperature requirements of the building. This
capability results in less temperature variation in the
building and therefore lower fuel consumption. The heater
can be configured to operate in either single stage or two
stage mode with either a thermostat or building controller.
Note that the heater is wired to start up and run only in the
first stage position as shipped from the factory.
Connection with a thermostat or building control is
required for further operation. The following instructions
provide interconnections for the two-stage gas control valve
in either single stage or two stage configuration utilizing
either a thermostat or building controller. Before
connecting any thermostat or building control, become
familiar with the heater's electrical connection diagram.
See diagrams within this manual or on the heater. Refer to
the index below to select specific wiring interconnections for
the temperature control device to be used.
The Therma Grow incorporates a manual heat - vent
switch. When in the 'heat' position, the heater operates nor-
mally. When in the 'vent' position, the heater fan operates
continuously. In the 'vent' mode, the heater then
supplements or provides air circulation within the
greenhouse. This heat - vent capability can be controlled by
a building controller. Before connecting to a building
controller,become familiar with the heater's electrical
connection diagram. See diagrams in this manual or on
the heater. When controlling the heat - vent position with a
building controller, if the building controller is in the 'vent'
position it must allow sufficient time for the fan to come to a
complete stop before switching to the 'heat' mode.
Owner's Manual • Therma Grow™
Regardless of control used:
n Open the heater's control box
n Locate the yellow wire connected from the 24 volt
output of the transformer to terminal W on the ignition
control.
-- Cut this wire at midpoint
-- Strip back insulation on ends 1/2 in.
n Using proper electrical connectors,connect wiring to
thermostat and gas control valve as shown.
-- Refer to respective diagram
-- Red lead for second stage heat is marked GAS
CONTROL HI.
n Close and latch the control box when done.
A. Two Stage Thermostat
Operate on First Stage and Second Stage Heat
B. Single Stage Thermostat
1. Operate on first stage heat only.