Tranquility THW - 50 & 60Hz R410A - ClimateMaster Geothermal Heat Pumps - Rev.: 30 June, 2008B
18
Warm weather shutdown (WWSD):
Radiant floor systems
are the most comfortable type of heating available today.
However, they do have one disadvantage – quickly
switching from heating to cooling is not possible due to the
mass heat storage in the slab. For example, in the spring
or fall, there could be times where heating is required
at night, but cooling is required during the day. With a
warm floor, the cooling system has to work much harder
to cool the space. WWSD shuts down the water-to-water
heat pump at a pre-determined outdoor air temperature
(adjustable at the user interface). When a water-to-air heat
pump is used for space cooling, this unit can be enabled
when WWSD is activate, allowing the water-to-air heat
pump to heat via forced air during the shoulder seasons,
avoiding the warm slab/cooling dilemma (see cooling
enable, below). A normally closed contact is provided in
the THW unit to de-energize the heating system controls
(e.g. radiant floor control panel) during WWSD. WWSD
does not affect DHW heating. In other words, the water-to-
water unit can still operate for generating DHW, even if the
heating distribution (e.g. radiant floor) system is disabled.
The WWSD activation (i.e. when the WWSD feature
is enabled) outdoor air temperature range is 40-100°F
[4-38°C] with a default value of 70°F [21°C]. The
WWSD deactivation (i.e. when the radiant heating
returns to operating mode) temperature range is 35-
95°F [2-35°C] with a default value of 65°F [18°C] and a
minimum difference between activation and deactivation
temperatures of 5°F [3°C]. If the outdoor air temperature
(OAT) rises above the activation temperature, the cooling
enable signal (see below) is enabled, and the control no
longer controls the buffer tank temperature. If the OAT falls
below the deactivation temperature, the control resumes
monitoring the buffer tank temperature.
Cooling enable: Cooling enable is tied to the WWSD
feature. If desired, the water-to-air unit controls can be
wired to the THW unit controls, which will allow the water-
to-air unit to operate during WWSD, but will disable the
water-to-air unit when the THW unit is not in WWSD mode.
When a heat pump thermostat is connected to the water-
to-air unit, forced air heating may be used for the shoulder
seasons, allowing quick heating to cooling changeover. If
this feature is used, the consumer will easily be able to
tell when WWSD is enabled because the water-to-air unit
thermostat will only be active during WWSD. Otherwise,
the water-to-air unit thermostat will be disabled, indicating
that the consumer should utilize the hydronic heating (e.g.
radiant floor) thermostat.
Second stage heating (backup boiler): Optimal heat
pump sizing may not include a water-to-water heat pump
that can handle 100% of the heating load. When a
backup boiler is used to supplement the heating capacity,
a 24VAC output from the THW unit can energize the
boiler. The boiler control box simply needs a relay that
can be used to interface with the THW unit.
DHW priority: By default, DHW heating always takes
priority over space heating. Normally, the hot water load
will be satisfied quickly, and the unit can then switch back
to space heating.
Time schedule: DHW temperatures may be adjusted
during occupied/unoccupied times via the user interface
to save energy costs.
Vacation mode: DHW generation may be disabled
when the user interface is placed in vacation mode. A
return date and time may be set to restore normal DHW
temperatures.
Emergency DHW generation: If the THW unit is locked
out, a 24VAC signal can be sent to a contactor at the water
heater to allow the operation of the electric elements and
associated thermostat.
Enhanced heat pump lockouts: Like any ClimateMaster
unit, the CXM board locks out the compressor any
time a lockout condition occurs. The MPC reads the
lockouts from the CXM, and reports the condition to the
user interface. The user interface changes from a blue
backlight to a red backlight, indicating a lockout. The
actual lockout is reported (e.g. High Pressure) at the
interface. In addition to the standard CXM faults, the
MPC checks for bad thermistors and high compressor
discharge temperature, which are also reported at the
user interface.
Pump control: If the optional load and source pump(s)
are selected, the control energizes the pumps any time
the compressor is operating.
Variable speed floor pump (VSFP) output:
Some radiant
floor systems utilize a variable speed pump on the floor
system, which changes flow based upon the number
of zones open or closed. Since the pump has built-in
controls, only a power supply is needed. An optional
power terminal is available for VSFP applications.
ELECTRICAL - CONTROLS
