Grain Systems PNEG-501 - Manual (Page 31)

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Fan/Heater Application
HEATER APPLICATION & SIZING
Fan selection and examination of a customer's
drying requirements should precede heater se-
lection. Generally, the size and type of fan, vane
axial or centrifugal, limits the choice of heater
to be used in a particular situation. For best
results GSI heaters should be matched with GSI
fans. When using more than one fan and heater
on a bin they should be of like sizes.
The available fuel source should be considered.
Liquid propane heaters are recommended in
areas where average outdoor temperatures dur-
ing drying may fall below 32 degrees F or where
over one million BTU/hr are used. This will
avoid unreasonable fuel tank capacities. LP
vapor heaters will function properly in most
other areas. For the best performance the proper
tank size should be used to provide the required
BTU/hr to the heater. Recommendations may
be obtained from the local gas supplier.
Natural gas operation requires proper fuel line
sizes with a regulator in the supply line. Sizing
of the lines should be done by the local natural
gas supplier. Where natural gas wells are used
gas quality should be evaluated periodically to
assure even continuous operation.
Whether a heater(s) is suited for a high or low
temperature drying situation can be determined
by checking its rated performance against the
operator's conditions.
The LTD heater is exclusively for low tempera-
ture drying. Generally, the electric and lo-fire
gas heaters are considered low temperature heat-
ers. Most other heaters can be operated as high
or medium temperature heaters with the proper
adjustments.
A thermostat is required when a heater is used.
The Series 2000 heater comes standard with a
thermostat sensor. Only 1 thermostat is re-
quired for each bin drying system. Thermostat
must be installed per instructions when two fan
and heaters are being connected. Connecting
two heaters in parallel to one thermostat
should never be done. A humidistat-thermo-
stat combination may also be used, but is not
recommended for high temp drying or locations
where there are wide variations in temperature.
It is important to advise the customer of proper
installation of thermostat for best results.
HI-LO heaters are used for high temp drying
systems where constant plenum heat is desir-
able. The heater switches between high and low
flame to maintain temperature within 6 degree
F in plenum. When using a HI-LO heater a HI-
LO thermostat is required. When connecting 2
HI-LO heaters to a bin a relay is required to plug
into main heater smart board. This allows both
units to cycle together.
Modulating valves are another optional feature
of GSI heaters. The heater has a mechanical
valve installed that maintains plenum tempera-
ture by constantly adjusting gas pressure.
Modulating valves are not recommended
when two heaters are used on a bin. A ther-
mostat is still required on units with modu-
lating valves.
Heater Sizing
The following formula may be used for calcu-
lating BTU's needed to heat the airstream pro-
duced by the fan. Formula should not be used
for accurate calculation of gas usage, use only
as a guideline.
CFM x 1.2x Degree of heat rise F=BTU's re-
quired
Example: To heat a 12000 CFM stream of air
to 140 Degrees ( 40 degrees Ambient )
12000 x 1.2 x (140-40) = 1,440,000 BTU's re-
quired