Auto Changeover Operation; Em Heat And Auxiliary Heat Operation; Adaptive Intelligent Recovery - Honeywell Home T10 Product Data

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Fig. 97.

Auto Changeover Operation

Auto changeover is available if the thermostat is configured
for at least 1 heat stage and 1 cool stage and ISU 3000 is set
to "Auto".
When configured this way, you can select "Auto" as one of the
options under "System mode".
ISU 3015 is the auto changeover differential setting. It can
be set from 0-3 °F (0-2.5 °C). When in auto mode, the
customer can always set the heat and cool setpoint to the
same temperature, regardless of the differential setting
although most customer prefer to have a cool setpoint that is
at least 3 degrees above the heat setpoint. When 0 is
selected, we enforce a 1.5°F differential behind the scenes to
ensure the heat doesn't come on after cooling shuts off or
vice-versa.
The differential is the minimum number of degrees the
temperature needs to rise or fall before switching from heat
to cool while in auto changeover mode. Example: With a
differential of 3, if heat and cool were both set for 70, and
heat had been used last, the temperature would need to rise
at least 3 degrees above the heat setpoint before the
thermostat would turn on cooling. Then it would run cooling
down to setpoint and cycle cooling on and off to maintain
setpoint. The temperature would then need to drop at least 3
degrees below the cool setpoint before heat could come on.
If the AC is used for dehumidification then we enforce an
additional temp drop below the overcooling amount, (ISU
9070) prior to switching back to heat.
Em Heat and Auxiliary Heat
Operation
Auxiliary heat:
Auxiliary heat runs as backup to the heat pump. It runs with
the heat pump when:
• The thermostat is set to heat mode.
• The backup heat is set to electric (ISU 2180).
• Load conditions determine backup heat is needed.
The heat pump could be locked out when in heat mode by the
balance point setting (ISU 3120) or if the backup heat is gas
or oil and backup heat differential (ISU 3090) or upstage timer
(ISU 3110) are used.
Emergency heat:
Emergency heat runs when you manually switch the
thermostat to the em heat mode. When the thermostat is in
emergency heat mode, the heat pump is locked out.
Emergency heat mode is only available when the thermostat
is configured for a heat pump (ISU 2000) and Backup heat
stages is set to 1 (ISU 2071).
From home screen touch the menu icon and then "system
Mode". You can set the thermostat to heat, off, cool,
emergency heat, or auto (auto only available if ISU 3000 is set
to auto).
When the thermostat is set to em heat mode, the heat pump is
locked out and the backup heat is used to maintain the heat
setpoint.
If ISU 2175 is set to "Drive aux and E together", then with a
call for emergency heat or auxiliary heat, both E and AUX
terminals are energized. Typically the backup heat is wired to
Aux and E is unused when set this way.
If ISU 2175 is set to "Aux and E independent", then with a call
for emergency heat, the E terminal is energized and the aux
terminal is not. The wire to Aux controls a heat source that
runs as backup heat to the heat pump when the mode is set to
"heat". The wire to E controls a heat source that runs
independent of the heatpump when mode is set to em heat. In
most cases, the heat pump uses the same heat source for
auxiliary heat and em heat.
Dual fuel systems (Heat pump with gas or oil furnace backup)
cannot run the heat pump and furnace at the same time.

Adaptive Intelligent Recovery

Over time, the T10 or T10+ thermostat "learns" how long it
takes your system to reach your programmed temperature
setting.
The thermostat turns on the heating/cooling system early and
assures that the programmed temperature setting is reached
at the programmed time regardless of weather conditions. For
example, if the Wake program period is set to 6:00 am with a
heat setting of 70 degrees, the heat will turn on before 6:00
am, so the temperature is 70 degrees at 6:00 am. The
thermostat displays "In Recovery" when it turns the system on
early.
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