Nordic R-45, Installation And Service Manual, Page: 7 / 91

1-Nov-2021 Page 7 001200MAN-09
Sizing
TABLE 2 - Heat Pump Size vs. Heated Area
for an Open Loop System
Model ft
2
m
2
R/RH-45 1800
165
R/RH-55 2500
230
R/RH-65 3200
295
R/RH-75 3800
355
R-80 4200
390
Heat Pump Sizing
The following table is a rough guideline as to the size of
space each heat pump size can handle for ground loop (closed
loop) installations.
The following table is a rough guideline as to the size of
home each heat pump size can handle for ground water (open
loop) installations.
THE TABLES ABOVE ARE FOR ESTIMATION ONLY.
THEY SHOULD NOT BE USED TO SELECT A FINAL UNIT
SIZE. They simply show what size unit is required for a
northern home with typical construction: R20 walls, R40 ceiling,
and average size and number of windows. The heated area is
the area of the above grade main level; the tables account for a
basement the same size as the heated area.
MARITME GEOTHERMAL LTD. HIGHLY RECOM-
MENDS THAT A PROPER HEAT LOSS/GAIN ANALYSIS BE
PERFORMED BY A PROFESSIONAL WITH APPROVED CSA
F-280 SOFTWARE BEFORE SELECTING THE HEAT PUMP
SIZE. For heating dominant climates, we recommend sizing
the unit to 100% of the heating design load for maximum
long term efficiency with minimal supplementary heat. The
unit should be installed as per CSA standard 448.2-02. For
ground loop applications, the ground loop should be de-
signed using suitable software with a multi-year analysis.
The analysis will result in a heat load for the coldest day,
which is influenced by, for example, the number of levels, the
size of the windows, the orientation of the home, attached gar-
age, bonus rooms, walk-in basement, and coldest outdoor tem-
perature for the region.
A heat pump model size can then be selected by compar-
ing the calculated heat load to the heat pump capacity at the
standard indoor air temperature, which can be found in the per-
formance tables in the Model Specific Information section. For
R-series, the
Standard Capacity Ratings
rather than detailed
performance tables can be used for simplicity. For 100% heat
pump sizing, choose a heat pump with a standard capacity rat-
ing that matches or just slightly exceeds the calculated heat
load.
Some background on
Standard Capacity Ratings
: closed
ground loops are normally designed to reach a minimum tem-
perature of just below freezing at the end of the heating season,
in order to take advantage of the latent heat of groundwater (at
least in northern climates). Hence, the Standard Capacity Rat-
ings for Ground Loop Heating should apply in all northern cli-
mates. Conversely, the Standard Capacity Ratings for Ground
Water (open loop) heat pumps assume a well water temperature
of 50°F (10° C). In more southerly climates, the groundwater or
ground loop will probably be at a warmer minimum temperature,
and it will be necessary to consult the more detailed perfor-
mance tables for heat pump output at a different ELT.
In cooling dominant climates, the heat pump should be
similarly sized using the Ground Loop Cooling or Ground Water
Cooling Standard Capacity Ratings. Even in northern heating
dominant climates, it should be ensured that 100% of the
cooling load will be covered when sizing the heat pump,
since there is normally no auxiliary or backup cooling avail-
able.
Plenum Heater Sizing
The plenum heater is available as an accessory in 5, 7, 10,
15 and 20kW sizes. If full backup is desired, choose a size that
covers 100% of the coldest day heat load , according to the heat
loss analysis mentioned in the last section. If that is not availa-
ble, use the following recommendation:
Two styles of plenum heater are available; the first is for R-
series internal installation (inside the indoor unit). Note limit for
size 45 in above table.
The second has a wider element profile for installation
outside the unit, in the ductwork. For RH series or for R series
when field-installing the fan in the convertible side discharge
position, this type of plenum heater should be used.
TABLE 3 - Plenum Heater Sizing
Model
Plenum Heater Size (kW)
Full Backup Possible Not Possible
R/RH-45 10 5, 7, 10 15, 20*
R/RH-55 10 5, 7, 10, 15, 20
R/RH-65 15 5, 7, 10, 15, 20
R/RH-75 20 5, 7, 10, 15, 20
R-80 20 5, 7, 10, 15, 20
* Although these plenum heaters will not fit inside heat pump,
there are versions available for external mounting.
TABLE 1 - Heat Pump Size vs. Heated Area
for a Ground Loop System
Model ft
2
m
2
R/RH-45 1400
130
R/RH-55 2000
185
R/RH-65 2600
240
R/RH-75 3100
290
R-80 3500
325