Friedrich VRP12K, Service And Parts Manual

Page: 119 / 221

119 PB
Determining the Indoor CFM
Model VRP12K/ VRP12R VRP24K/ VRP24R VRP36K
Air Flow Data
Indoor CFM
Low High Low High Low High
.10” ESP* 488 559 472 850 - -
.15 ESP* - - - - 1015 1200
.20” ESP 393 466 432 778 875 1160
.30” ESP 292 383 391 703 750 1080
.40” ESP 200 304 348 626 565 970
.50” ESP 104 234 308 555 440 835
* Rated at 0.10” ESP, High and includes 0.08” ESP for factory installed 1” filter
Correct CFM (if needed): Correction Multipliers
230V
1.00
208V 0.97
265V
Heating
1.00
Cooling 0.95
Explanation of charts
Chart A is the nominal dry coil VRP CFMs. Chart B is the correction factors beyond nominal conditions.
1 ½ TON SYSTEM ( 18,000 Btu)
Operating on high speed @ 230 volts with dry coil
measured external static pressure .10
Air Flow = 450 CFM
In the same SYSTEM used in the previous example but having a WET coil you must use a correction factor of .95 (i.e. 450 x .95=428
CFM) to allow for the resistance (internal) of the condensate on the coil.
It is important to use the proper procedure to check external Static Pressure and determine actual airfl ow. Since in the case of the VRP,
the condensate will cause a reduction in measured External Static Pressure for the given airfl ow.
It is also important to remember that when dealing with VRP units that the measured External Static Pressure increases as the
resistance is added externally to the cabinet. Example: duct work, filters, grilles.
Indoor Airflow Data
The VRP A series units must be installed with a free return air configuration. The table below lists the indoor airflow at corresponding
static pressures. All units are rated at low speed.
The VRP units are designed for either single speed or two fan speed operation. For single speed operation refer to the airflow table
below and select the most appropriate CFM based on the ESP level. Connect the fan output from the thermostat to the unit on either the
GL terminal for low speed or to the GH terminal for high speed operation.
For thermostats with two‑speed fan outputs connect the low speed output to the unit GL terminal and the high speed output to the GH
terminal.
EXTERNAL STATIC PRESSURE