Filter
Top Products
17
LTD HEATER OPERATION
Your LTD heater is equipped with
a modulating valve. The following
material should be read thor-
oughly.
1. The modulating valve regulates
gas flow through heater based
on sensing unit in the plenum,
and maintains a constant drying
air temperature.
2. The sensing bulb of the modu-
lating valve should be mounted
through the bin wall with the
reading side top up. The bulb
reacts to temperature. It
changes the amount of gas (in
crease or decrease), burning
warmer or cooler depending on
the position of the valve SET
POINT. If the bulb is cooler than
it was at the SET POINT, the
bulb senses the cooler tempera-
ture and opens the valve further
so more heat is applied to the
drying air. If the bulb is warmer
than it was at the SET POINT,
the valve closes further and re
duces the temperature until the
air is at the valve SET POINT.
3. It is important that the pressure
regulator be set high enough to
allow the modulating valve to
deliver enough gas to maintain
the plenum temperature neces-
sary. The regulator is normally
factory set at 15 psi. To set the
tions as long as humidistat or
thermostat do not shut down the
heater. A bypass orifice is used
to maintain a small flame when
outside temperature is near or
above the set point of the valve.
The bypass insures steady
application of heat at minimum
gas flow operation.
6. The modulating valve may re-
quire minor adjustment periodi-
cally if a certain temperature rise
over ambient (outside) tempera-
ture is desired.
7. To observe how the modulating
valve increases the efficiency of
bin drying, check the gas pres-
sure of the unit in the morning
and compare to the pressure
read mid-afternoon. If the ambi-
ent (outside) temperature is sig-
nificantly greater later in the day
(as normal), the gas pressure
will be less. Since less heat is
required to maintain the same
temperature in the plenum, the
modulating valve will have re-
duced the amount of gas used
by the heater. This is preferred
to cycling the application of heat
as is commonly done. The grain
is not shocked and cooled
quickly and then reheated,
which is a waste of fuel in con-
ventional bin drying systems.
regulator, run the heater and turn
the modulating valve T-handle
in. This gets full line pressure to
the burner. Then adjust regula-
tor to read 15 psi (depending on
the plenum temperature needed).
4. Turn the fan and heater on. To
set the modulating valve, turn the
T-handle out (counterclockwise)
until loose and wait a few min-
utes for the plenum temperature
to equalize. When the tempera-
ture under the bin has equalized,
gradually turn T-handle in (clock
wise) about 1/2 turn. Wait until
temperature under bin has
equalized as before. If tempera-
ture under bin is less than the
desired temperature, continue
turning T-handle in, increasing
gas flow and waiting for plenum
temperature to equalize until the
desired temperature is the
stable temperature of the ple-
num. If temperature under bin is
the same 10 minutes after you
last made any adjustments to
the T-handle you can be certain
that the temperature under the
bin is the SET POINT of the
valve. 1 turn of the T-handle
equals approximately 7 de-
grees F of temperature.
5. The valve will now keep the ple-
num temperature at the set point
regardless of ambient condi-
MODULATING VALVE OPERATION