Product Brochure

17
6-175.7
UNIT SELECTION
With the information listed above, the basic model, using the
information in this catalog and the Model Nomenclature shown
on page 23, can be selected as shown:
1. Determine the Model and Input Rating (MBH):
Using the Heating output capacity, the Furnace Input Rating
is determined from Table 7.1. The closest model to 156,000
Btu/Hr output has an Btu/Hr Input rating of 200,000 Btu/Hr so
the Furnace Input Rating = 200. The corresponding model
for a 200 size, blower, separated combustion unit heater is
BTS. The model and size are a BTS200.
2. Determination of Heat Exchanger Material:
From item #4 in the example, the Heat Exchanger required
is aluminized steel. Thus, the Heat Exchanger Material = A
from the Model Nomenclature on page 23.
3. Determine the Ignition Type:
The Ignition Type = S from the Model Nomenclature on page 23.
4. Determine Power Code Required:
From page 10 we see that a unit requiring a static of 0.2 and
a cfm of 2400 requires a 1/2 horsepower motor with a -233
drive that is turned open 1.5 turns. Referring to Table 9.1 it
can be determined that for a BTS200 with a 1/2 HP motor
and a -233 drive operating on 230V/60Hz/3Ph that it will
have a power code = 08. However, note that if filters are
added later, that drive/motor combination will not be
sufficient. Two alternate drive selections could have been
made with a 1hp motor with either a -253 or -229 drive.
The power code would be 30 or 19 respectively. Note that
the 229 drive would likely be the best choice, as the turns
open is near the center of the range.
5. Determine the control type:
From items #5 and #6 in the example, the gas type is
Propane Gas and controls are Two Stage. From Table 12.2,
we are directed to use Control Code (CC) = 22.
Selection Example Conditions (Blower Unit)
In the following example, select a unit heater to meet the
following conditions:
1. Heating output capacity = 156,000 Btu/Hr per design
engineer
2. External Static Pressure = 0.2.
3. Internal Static Pressure = 0.0. No static producing
accessories are required at this point, but filters may be
added later.
4. Heat exchanger and burner = Aluminized Steel
5. Gas Type = Propane
6. Gas Controls = Two Stage
7. Supply Voltage: 230V/60Hz/3Ph
8. CFM = 2,400
Selection Example (Blower Unit)
At this point we have a full model number of:
BTS200AS1922NBAN
6. Determination of Transformer:
To operate the BTS200AS1922NBAN on 230V/60Hz/3ph
supply voltage, we need to review Table 12.1 to determine if
any field installed transformers are required. The table
indicates that we need a 230V to 115V step down transformer
for the power exhaust and gas control circuit voltage. As
indicated in the footnote for that table, Table 7.5 directs us to
the correct size for this model, which is 0.5kVA. Transformers
for blower models are typically smaller than those used for
propeller models, as the transformer is not needed for the
blower motor.