Performance Data Selection Notes - Heat Controller HBH Series Engineering Design Manual

Engineering Design Guide
For operation in the shaded area when water is used in lieu of
an antifreeze solution, the LWT (Leaving Water Temperature)
must be calculated. Flow must be maintained to a level such
that the LWT is maintained above 42°F [5.6°C] when the
JW3 jumper is not clipped (see example below). Otherwise,
appropriate levels of a proper antifreeze solution should be
used in systems with leaving water temperatures of 42ºF [5.6°C]
or below and the JW3 jumper should be clipped. This is due
to the potential of the refrigerant temperature being as low as
32°F [0°C] with 40°F [4.4°C] LWT, which may lead to a nuisance
cutout due to the activation of the Low Temperature Protection.
JW3 should never be clipped for standard range equipment or
systems without antifreeze.
Example:
At 50°F EWT (Entering Water Temperature) and 1.5 gpm/ton, a
8 ton unit has a HE of 72,200 Btuh.
To calculate LWT, rearrange the formula for HE as follows:
HE = TD x GPM x 500, where HE = Heat of Extraction (Btuh);
TD = temperature difference (EWT - LWT) and GPM = U.S.
Gallons per Minute.
TD = HE / (GPM x 500)
TD = 72,200 / (12 x 500)
TD = 12°F
LWT = EWT - TD
LWT = 50 - 12 = 38°F - antifreeze must be used
In this example, a higher fl ow rate will be required for EWTs at or below 50°F without antifreeze.
HBH SERIES
WATER/BRINE
EWT FLOW PD
°F gpm psi
12.0
50
18.0
24.0
7
Heat Controller, Inc.
Performance Data
Selection Notes
HBH096
Heating - EAT 70°F
PD
HC kW HE
ft.
1.7 4.0 96.7 7.17 72.2
4.5 10.3 101.9 7.27 77.1
7.9 18.2 104.7 7.32 79.8
LAT COP
95.9 4.0
97.4 4.1
98.2 4.2