|
Programmable Thermostats on Furnaces |
|
rev. 2008-12-07
|
|
|
Programmable Thermostats on Furnaces |
|
|
rev. 2008-12-07
|
|
Existing Conditions
There are several natural gas fired furnaces located throughout the xxx building. These furnaces are controlled by simple wall mounted thermostats, which control to a single setpoint all the times.
Retrofit Conditions
It is recommended that electronic setback thermostats be installed, to reset the space temperature of the shop areas to 15°C during unoccupied times. Typically, space temperature during occupied periods would be set at 21°F for heating and 24°F for cooling. During unoccupied periods temperature would be allowed to drift within a wider range (e.g. 18°C to 27°C).
<The supply fan would operate continuously during occupied periods. It would cycle off in the unoccupied mode, only coming on when either heating or cooling were needed.>
<Because this unit has economizer damper control, we recommend using a thermostat that has 'damper override' capability. This feature disables economizer damper operation during unoccupied mode, so that the dampers remain fully shut and the air handler does not bring in ventilation air.>
We recommend using a commercial grade "heating only" setback thermostat that takes power from a low-voltage control transformer. Residential grade thermostats are typically less expensive, but they are less rugged, require battery replacement and are prone to corrosion of the battery contacts.
In most cases we would recommend allowing occupant access for fine-tuning of the setback schedule. However, if occupant adjustment is not desirable, consider a thermostat with a password lockout to prevent undesired access.
Further Benefits