Hot Water Generator Module - Heat Controller HSS Series Installation, Operation & Maintenance Instructions Manual

H E AT C O N T R O L L E R , I N C . W AT E R - S O U R C E H E AT P U M P S
R e s i d e n t i a l S p l i t - 6 0 H z R 2 2 & R 4 1 0 A
R e v. : 5 J u n e , 2 0 0 8
The HWG (Hot Water Generator) or desuperheater
option provides considerable operating cost savings by
utilizing excess heat energy from the heat pump to help
satisfy domestic hot water requirements. The HWG
is active throughout the year, providing virtually free
hot water when the heat pump operates in the cooling
mode or hot water at the COP of the heat pump during
operation in the heating mode. Actual HWG water
heating capacities are provided in the appropriate heat
pump performance data.
Heat pumps equipped with the HWG option include
a built-in water to refrigerant heat exchanger that
eliminates the need to tie into the heat pump refrigerant
circuit in the field. The control circuit and pump are also
built in for residential equipment. Figure 15 shows a
typical example of HWG water piping connections on
a unit with built-in pump. This piping layout minimizes
scaling potential.
Electric water heaters are recommended. If a gas,
propane, or oil water heater is used, a second preheat
tank must be installed (Figure 16). If the electric water
heater has only a single center element, the dual tank
system is recommended to insure a usable entering
water temperature for the HWG.
Typically a single tank of at least 52 gallons (235 liters)
is used to limit installation costs and space. However,
a dual tank, as shown in Figure 16, is the most efficient
system, providing the maximum storage and temperate
Figure 15: Typical HWG Installation
(Indoor Compressor Section)
22
H e a t C o n t r o l l e r, I n c . W a t e r - S o u r c e H e a t i n g a n d C o o l i n g S y s t e m s
Hot Water Generator
source water to the HWG. Using a concentric or coaxial
hot water tank connection fitting eliminates the need to
tie into the hot water tank cold water piping, but is more
susceptible to scaling. The optional concentric fitting
(part # S69619804) is available from your equipment
supplier and should be installed as shown in Figure
17 for applications with low scaling potential or where
a water softener is used. Consult Table 3 for scaling
potential tests.
It is always advisable to use water softening equipment
on domestic water systems to reduce the scaling
potential and lengthen equipment life. In extreme water
conditions, it may be necessary to avoid the use of
the HWG option since the potential cost of frequent
maintenance may offset or exceed any savings.
R-410 systems inherently have a lower hot gas
temperature than R-22 systems because the
equipment is more efficient (i.e. less waste heat
is available). It is possible that energy could be
transferred from the water heater to the hot gas line
instead of from the hot gas line to the water heater
during certain times of the year. To prevent this from
occuring, a temperature switch will deactivate the
pump at those conditions that typically occur in the
cooling mode with entering water temperatures of less
than 50°F [10°C].
Figure 16: HWG Double Tank Installation
(Indoor Compressor Section)