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Ranco
electronic defrost controls are designed to control the removal
of frost and ice from the outdoor coil of an air - source heat pump
(unitary and split systems).
SPECIAL
FEATURES
- Microprocessor - based control, providing:
- Fewer parts for greater reliability and quality.
- Lowest cost factory programming of new features.
- Superior nuisance electrical noise filtration.
- Accurate timing, based on line frequency; immune to aging
effects of traditional RC timers.
- Demand Defrost algorithm available
- D.O.E. approved for energy credit.
- Defrost occur only when needed.
- Fast test mode for systems diagnostics.
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OPTIONAL
FEATURES
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Both
the basic Time / Temperature and advanced Demand Defrost controls
are available with additional features and functions integrated
on the control itself that allow the manufacturer to enjoy both
enhanced performance and reduced total cost benefits. These available
optional features include:
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- Anti-short cycle protection for the compressor that allows elimination
of a separate relay and associated wiring.
- Integral relays for the control of components such as the compressor,
indoor air blower, outdoor fan, reversing valve, and auxiliary
heat eliminate the need for separate relays and their associated
wiring.
- Timer reset for elimination of unwanted defrost initiations.
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- Integral coil temperature sensor that allows more accurate temperature
measurement as well as the elimination of a separate thermostat.
- On-board or integral outdoor air temperature sensor which allows
elimination of a separate thermostat and associated wiring and
allows the integrated control of the compressor, indoor air blower,
and auxiliary heat.
- Reversing valve control (valve switching logic).
- On-board diagnostics assist service personnel in troubleshooting
during service calls.
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TYPE
SELECTION
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DT
Series
- Basic Time / Temperature defrost function - only control. Defrost
is initiated when the system run time exceeds a predetermined value
selectable by the user or when the outdoor coil enable temperature
and elapsed time values are reached. The defrost cycle is terminated
based on either a fixed factory selected time interval or upon temperature
as determined by the external coil thermostat or integral coil temperature
sensor.
DTL
Series - Time / Temperature defrost function as described above
with additional integrated functions incorporated on the board.
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DD
Series - Demand Defrost function - only control. Using a patented
demand defrost algorithm, the control's microprocessor looks at
the relationships between compressor run time, ambient air temperature,
and outdoor coil temperature which define conditions under which
defrost should occur. Defrost is initiated when the control determines
that the system heat transfer has degraded to a point where it becomes
less efficient to continue to operate the heat pump with accumulated
ice than to spend the energy to defrost. Defrost is terminated after
a fixed factory selected time interval or based upon temperature
as determined by the coil temperature sensor.
DDL
Series
- Demand Defrost function as described above with additional integrated
functions incorporated on the board.
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TYPICAL
SPECIFICATIONS
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Temperature
40C to 85C (Storage).
-40C to 60C (Operating).
Humidity
0 to 100%RH, non-condensing.
Connectors
1/4" male quick connect terminals or terminal block.
Mounting
Metal eyelet stand-offs or plastic stand-offs.
Power Input
24 VAC nominal, 50/60 Hz.
Hold Input
10 mA max @24 VAC.
Output Devices
Normally open triacs -
400 mA @ 60C, 24 VAC.
Relays - various ratings available.
Hold Time (T1/T2/T3)**
As specified:
30/60/90 minutes.
30/45/90 minutes.
50/70/90 minutes.
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Defrost
ON Time**
10 or 14 minutes or as specified.
Short Cycle Delay***
3 or 5 minutes or as specified.
Time accuracy
± 1%
Enable temperature***
Determined by external stat or 28° F to 40°
F + 1.8°
F
Termination temperature***
Determined by external stat or 45°
F to 85°
F + 1.8°
F.
*Applicable only when compressor anti-short cycle protection is
installed.
**Timing based on 60 Hz AC voltage; should 50 Hz power be utilized,
all timing values will be extended by 20%; T1, T2, and T3 are changeable
by jumpers and applicable to the DT and DTL series controls only.
Other times are factory set.
***The temperature values shown are those for controls which incorporate
an integral temperature sensor. Enable temperatures are factory
set; termination temperature can be field selectable.
UL/CSA Approvals
DT, DTL, DD, and DDL control series pass all tests in UL873 and
are UL recognized components. UL file number E78518, Volume 1, section
4 (DT), sections 5 and 6 (DTL), section 8 (DD), section 12 (DDL).CSA
file number LR 59494.
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