WaterFurnace Envision Hydronic (NSW) - Manual (Page 28)

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NSW INSTALLATION MANUAL
Standard Board - Control Features
Anti Short Cycle Time
The anti short cycle time consists of a three minute
minimum “off” time plus a randomly chosen 0-2 minute
additional “off” delay. The random delay is chosen by the
control after each compressor shut down. The 3-5 minute
startup delay is applied after all compressor shutdowns and
also to system startups due to ac power interruption.
Safety Controls
The control board receives separate signals for a high
pressure switch for safety, low pressure switch to prevent
loss of charge damage, and a low suction temperature for
freeze detection. Upon a 30-second measurement of the
fault (immediate for high pressure), compressor operation is
suspended and the fault will be shown on the display.
Setpoint Temperature Ranges
In Primary mode, the heating temperature setpoint range
is adjustable from 60°F (15.5°C) to 130°F (54.4°C) with
an adjustable deadband range of 1° - 15°F. The cooling
setpoint temperature is adjustable from 25° (-3.9°C) to 85°F
(29.4°C) with a fixed non-adjustable deadband of 5°F.
Load Pump Control
There are two options for controlling the load pump, Pump
Sampling (PS) or Continuous Pump (C), and these are
selectable in the service Menu.
Pump Sampling (PS)
In Primary Mode, the control operates on a 10 minute
sample cycle in which the load pump is turned on and
run to obtain a meaningful sample of the temperature
the load is presenting. If the water temperature
measured after the pump has been on for PS minutes
(selected and adjusted from the Service Menu) is
outside the user selectable deadband amount, dB
(also selected and adjusted from the Service Menu),
the compressor is turned on and Heating or Cooling
is initiated. If the water temperature is within the
deadband of the set point when sampled, the pump
shuts off and is idle for (10 – PS) minutes when it starts
another PS minute sample period. For example, if
the PS setting is two minutes, the pump will run for 2
minutes before sampling the load temperature. If the
water temperature is within the selected dead band
temperature of the set point, the pump will shut off
for 10 – 2 = 8 minutes before beginning another pump
sampling cycle. Heating deadband is selectable in the
Service Menu while the Cooling deadband is non-
adjustable and fixed at 5°F.
Continuous Pump Mode (C)
If continuous pump mode (PS=C In Service Menu) is
selected, the control will respond immediately to a
recognized call or termination of call for heat or cool
subject to minimum run times and anti short cycle delays.
Test Mode
Connection of a jumper wire from chassis ground to P3
will place the control in the test mode. This shortens most
timing delays for faster troubleshooting. In the Primary
Mode the control will respond immediately if a demand
is present. The anti-short cycle delay is replaced by a
10 second pump and compressor on delay. Minimum
compressor run time becomes 15 seconds. Test mode will
remain in effect for a maximum of 15 minutes at any one
time should the jumper remain in place.
Fault Conditions
There are two classes of faults, retry faults and no retry
faults. Retry faults allow the system to try 2 additional times
to establish operation before displaying the fault condition
and entering lockout. No-Retry Faults prevent compressor
operation for the duration of the fault. If the fault activity
ceases while the system is inactive, the fault code is cleared
from the display and operation is permitted.
Retry Faults
High pressure, low pressure and freeze detection
faults are retried twice before locking the unit out and
displaying the fault condition.
High Pressure (HP)
Compressor operation will be disabled immediately
when the normally closed high-pressure switch is
opened momentarily (set at 600 psi). The LED display
shall read “HP” only when the control has completed
two retries, and is in lockout. The pump continues to
operate throughout the retry period.
Low Pressure (LP)
Compressor operation will be disabled when the
normally closed low-pressure switch (set at 40 psi)
has opened for 30 continuous seconds (if the bypass
period has been satisfied). The Low Pressure switch is
bypassed (ignored) for two minutes after startup. The
LED display shall read “LP” only when the control has
completed two retries, and is in lockout. The pump
continues to operate throughout the retry period.
Freeze Detection (FP)
Compressor and loop pumps will be disabled if the
control senses that the refrigerant loop temperature
drops below the FP value (set in the service menu) for
30 continuous seconds (if the bypass period has been
satisfied). If the compressor and the loop pump outputs
are disabled because of this condition, the LED display
shall read “FP.” There is a two (2) minute by-pass timer
for the freeze detection at compressor start up.
No-Retry Faults
High Temperature, Water Temperature Probe Open,
Water Temperature Probe Closed and Brown Out faults
prevent compressor operation for the duration of the