Selection Procedure - Rheem RHWB-04WMP36A Installation Instructions Manual

SELECTION PROCEDURE

(WITH EXAMPLE)
I. Define hot water load for the total
required domestic hot water
usage.
As an example, let's assume that the
selected Tankless Water Heater for your
whole house solution is the RTG-74 and
your calculated heat gain and heat loss
values are as stated in section II.
II. Determine cooling and heating
requirements at design conditions:
The ACCA's Manual J Residential Load
Calculation method is the established
trade standard, approved by ANSI, for
the correct siziing and selection of
Heating, Ventilation, Air-Conditioning
and Refrigeration (HVACR) equipment in
residential homes. The most recent
revision is the eight edition, an all-
inclusive new approach to ensuring that
Indoor Air Quality (IAQ) systems are as
efficient, safe, and healthy as possible.
Refer to the Air Conditioning Contractors
of America website at:
http://www.acca.org/tech/manualj/ or a
qualified HVACR contractor for further
assistance.
Model Number Nomenclature
Rheem
Air Handler
Water
Design Series
Denotes a major design change in the
product line (i.e. capacity)
Nominal Heating Capacity (BTU/HR)
04W 40,000
06W 60,000
08W 80,000
10W 100,000
HYDRONIC AIR HANDLER MODEL IDENTIFICATION
R H
Brand pplication
R = Rheem H = ir handler W = Water
8
Assumptions:
Required Cooling Capacity . 48,000 BTU/HR
(Total Capacity)
Required Heating Capacity . 60,000 BTU/HR
Evaporator Air Quantity. . . . . . . . . 1600 CFM
External Static Pressure . . . . . . . 0.2 in. W.C.
Electrical Characteristics . . . . . . . . . 115-1-60
III. Determine total external static
pressure (ESP) at design
conditions:
Before using the Airflow Performance
Table calculate the total static pressure
required. From the given example, note
the Wet Coil Pressure Drop (selected
from the field supplied Evaporative
Cased Coil Installation Instructions), and
the Filter Pressure Drop. Determine both
static pressures at 1600 CFM:
Wet Coil Pressure Drop . . . .0.3 in. W.C.
(From Coil Manufacturer's Installation Instructions)
External Static Pressure . . . 0.2 in. W.C.
3
RHWB 04W M P 36
W B
Heating Output Designation
Design
Inlet Water
Type
Series
Temp = 150°F
[66°C]
04W
06W
B = 2nd Series
08W
10W
2
(Ductwork, etc.)
08 K A 5
A
36 = 1100-1300 CFM
48 = 1500-1700 CFM
60 = 1900-2100 CFM
Variations
P = PSC Motor
X = ECO Tech
Blower Size
M = 11x7
R = 11x10
-06W M
Blower
Output
Size
BTU/HR [kW]
40,000 [11.7 kW]
M = 11x7
60,000 [17.6 kW]
[279 x 178 mm]
80,000 [23.5 kW] R = 11x10
[279 x 254 mm]
90,000 [28.3 kW]
Filter Pressure Drop . . . .08 in. W.C.
(.08 inches if the included filter is used; refer to
the filter's manufacturer's instructions if another
filter is used.)
Total Static Pressure. . . 0.58 in. W.C.
IV. Select unit based on required
cooling capacity airflow:
For an initial selection, choose a unit
size that will provide the required
airflow. Refer to Airflow Performance
Table. Note that at 0.6 ESP (external
static pressure) the RHWB-
06WMP48A unit will deliver 1560
CFM when configured for HIGH
speed.
V. Select heating capacity of unit
to provide the requisite design
condition:
From the Hydronic Air Handler/
Tankless Water Heater, note that the
unit RHWB-06WMP48A, (as selected
above) when matched with the RTG-
95 Tankless Water Heater, will
provide 59.2 MBH (59,200 BTU/HR)
at an input water temperature (to Air
Handler) of 150°F.
M
Revision
A = Rev 0
P 36
Heat/Cool
Variations
Designation
36 = 1100-1300 CFM
36 = [519-613.5 L/s]
P = PSC
48 = 1500-1700 CFM
X = ECO
48 = [707.9-802.3 L/s]
TECH™
60 = 1900-2100 CFM
60 = [896.7-991.1 L/s]
3
A
Revision
- Rev 0