Installation and Setup
Description of functions
Ot Minimum boiler off time: Check proper setting for your system (see page 23).
Cr Cycles per hour: Check proper setting for your system (see page 23).
Ot Proportional band width: If your heating system is oversized for your home, you can compensate by increasing the width of the control proportional band up to 3°C.
tO Temperature offset: In some cases, the thermostat must be installed in a location that does not accurately control temperature for optimum comfort in other rooms. You can set the thermostat to compensate for this by adjusting the offset.
uL Maximum temperature: When the p button is pressed, the thermostat will not allow a target temperature above the maximum you set.
LLMinimum temperature: When the q button is pressed, the thermostat will not allow a target temperature lower than the minimum you set.
ES ECO default temperature: This is the default target temperature when the thermostat is in ECO mode (see page 11).
HCHeating/cooling options: When set to 1, the thermostat can control both heating and cooling systems (see page 9).
OS Frost protection temperature: Minimum temperature allowed when the thermostat is off (see page 8).
EH Electric heat: Check proper setting for your system (see page 23).
| homexperttm by Honeywell THR840DUK Digital Thermostat | ||
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In case of difficulty |
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Thermostat screen | • Make sure two fresh AA alkaline batteries are properly installed (see |
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is blank | page 18). |
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Heating or cooling | • Check thermostat batteries (see above). |
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system does not | • Make sure heating or cooling system has power. Check fuses and |
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respond |
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circuit breakers and replace or reset as needed. |
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| • Check wiring (pages |
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Desired temperature | • If above remedies cannot resolve the problem, the thermostat may |
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cannot be maintained | have to be moved. Make sure it is not installed near sources of hot or |
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| cold air (radiators, windows, heating or cooling ducts). |
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| • If this symbol flashes on the screen during normal operation, a fault has |
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| occurred. Contact Honeywell Customer Care for assistance (see back |
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| cover for contact information). |
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24 | 25 |
