Brochure

14
6-170.9
SELECTION EXAMPLE - MODEL BTC (BLOWER UNIT)
With the information listed above, the basic model, using the
information in this catalog and the Model Nomenclature shown
on page 19, 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 6.1. The closest model to 195,000
Btu/Hr output has an Btu/Hr Input rating of 215,000 Btu/Hr so
the Furnace Input Rating = 215. The corresponding model
for a 215 size, blower, separated combustion unit heater is
BTC. The model and size are a BTC215.
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 19.
3. Determine the Ignition Type:
The Ignition Type = S from the Model Nomenclature on page 19.
4. Determine Power Code Required:
From page 9 we see that a unit requiring a static of 0.2 and a
cfm of 2600 requires a 1 horsepower motor with a -275 drive
that is turned open 3 turns. Referring to Table 7.1 it can be
determined that for a BTC215 with a 1HP motor and a -275
drive operating on 230V/60Hz/3Ph that it will have a power
code = 84. However, note that if filters are added later, that
drive/motor combination will not be sufficient. One alternate
drive selection could have been made with a 1HP motor with
a -276 drive. The power code would be 85.
5. Determine the control type:
From items #5 and #6 in the example, the gas type is
Propane Gas and controls are Single-Stage. From
note o on page 4, we are directed to use Control Code
(CC) = 21.
Selection Example Conditions (Blower Unit)
Select a unit heater to meet the following conditions:
1. Heating output capacity = 195,000 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 = Aluminized Steel
5. Gas Type = Propane
6. Gas Controls = Single-Stage
7. Supply Voltage: 230V/60Hz/3Ph
8. CFM = 2,600
Selection Example (Blower Unit)
At this point we have a full model number of
BTC215AS8421NBAN
6. Determination of Transformer:
To operate the BTC215AS8421NBAN on 230V/60Hz/3ph
supply voltage, we need to review Table 10.1 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 6.4
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.