Therma Grow™ Greenhouse Heaters
www.lbwhite.com
Owner’s Manual • Therma Grow™
20
FIG. 15B
Therma Grow 120 Models
Igniter
1. Disconnect the plastic male and female plugs located at
the end of the igniter leads. See Fig. 16.
FIG. 16
2. Remove the screw securing the igniter to its bracket.
Flame Sensor
1. Remove the sensor from its mounting bracket. Clean the
sensor’s rod with emery cloth or steel wool to buildup of
dirt to help maintain proper flame sense. See Fig. 17.
2. Check the flame sensor’s insulative base for any cracks.
If cracks are found, replace the sensor.
n
For proper flame sense operation, the flame
sensor tip must be properly positioned within the
burner flame. See Fig. 17.
FIG. 17
Gas Pressure Checks
n
The following explains a typical procedure to be
followed in checking gas pressures.
n
Consult the dataplate on the heater or page 4 in
this manual for specific pressures to be used in
conjunction with this procedure. The gas pres-
sures will vary depending upon fuel type.
n
Gas pressure measured at the inlet to the
gas valve is Inlet Pressure and gas pressure
measured at the outlet of the gas valve is Burner
Manifold Pressure.
Materials Required
(To be secured through local purchase)
Quantity
Description
2
Gas pressure gauges
capable of reading
up to 35 in. W.C. (may
also be ordered
from L.B. White, part
number 00764)
A. Preparation
1. Disconnect the heater from the electrical supply
and close the fuel supply valve to the heater inlet.
2. Open the case access panel at gas inlet end of
heater.
3. Brush or blow off any dust or dirt in the vicinity of
the gas control valve.
ORIFICE
BLOCK
ORIFICE