|
When
installing a remote sensor, be sure that the proper jumper
on the back of the thermostat (not the subbase), has been
clipped and the ends separated, as pictured in the installation
instructions for the remote sensor. On Comfort-Set II
(-71) single stage models, clip jumper wire W-22; on Comfort-Set
II (-71) multistage and heat pump models, clip jumper
wire W-18.
To
function correctly and read temperature accurately, the
thermostat (when using a remote) must have constant 24
volt power. If the thermostat
temperature is steadily dropping, reading low, or reads
08° when a
remote sensor is installed, it can be traced to one of
the three following conditions.
| Condition |
Test |
Comments |
| 1.
Loss of 24 volt power. |
Remove the batteries
and re-install thermostat. If display goes blank,
check heating and cooling
system to determine why 24 volt power is absent. |
For the sensor
to read correctly, the 24 volt system power
must be present. Some systems may require an isolation
relay to provide constant power to the thermostat.
Limit or safety devices in the equipment can also
cause a power interruption.
|
| 2. A broken wire
on S1, S2 and S3 from the thermostat to the remote.
|
Disconnect sensor
wires at thermostat. Attach a short piece (2’) of
three wire conductor thermostat wire to S1, S2 and
S3 on the sub-base. Bring the remote sensor to the
thermostat location and attach S1, S2 and S3 respectively.
Reattach thermostat. If the temperature begins to
climb (slowly), it is reading correctly. If it reads
correctly with the 2’ length but improperly when attached
to the wire run, there may be a fault in the wire
run. |
Repair or replace
the 3 wire shielded cable. Also be sure the remote
wire run is not parallel to line voltage wires that
carry heavy inductive loads, or across fluorescent
light ballasts that may cause an inductance to be
transmitted to the thermostat. |
| 3. A shorted or
damaged remote sensor. |
If you have tested
1 & 2 above and the temperature stays at or near
08°, it indicates a shorted or damaged remote
sensor. |
Replace remote
sensor. |
Installation
note:
When you clip the jumper lead (W-18 or W-22) on the thermostat
to add a remote sensor, it disables the thermostats temperature
sensor. This causes the room temperature display to start
dropping very slowly until the remote sensor is installed
and the power is restored. It is possible for the room
temperature to read as low as 08°. Digital thermostats
and remote sensors acclimate very slowly to temperature
change. It may take an hour or more for the temperature
to acclimate to the room temperature. As a general rule,
if the temperature is dropping (well beyond the actual
room temp), one of the conditions in the chart above has
occurred. If the temperature is climbing, it will eventually
reach room temperature and read correctly. To expedite
the rise in temperature from 08, remove the batteries
for five minutes and allow the thermostat to default to
factory settings. |
