Carrier E-20 - Throttling Range

[remp]

Im using carrier E 20 to do load calculations.

From the clients brief the space design temperature is 76 'F, + or - 2 'F....ie.74-78 F

Does this mean on Carrier E 20 you input 74 F for the T stat setpoint and 4 deg F for the throttling range??

 

[VSSriram]

The setpoints are used in conjunction with the thermostat throttling range to simulate thermostat behavior using a simple proportional model of cooling and heating control. The size of the throttling range is usually determined by the type of thermostat used.

Example: Consider the following thermostat settings:

Cooling setpoint = 74 F
Heating setpoint = 70 F

Throttling range = 4 F

For cooling the system maintains the zone between 74 F and 78 F. Therefore the cooling setpoint defines the lower limit of the cooling range. Setpoint plus throttling range defines the upper limit of the range. When the zone air temperature is at 74 F, the thermostat is calling for minimum cooling. When the zone air temperature is 78 F, the thermostat is calling for maximum cooling. Between 74 F and 78F, the call for cooling increases in proportion to zone temperature.

For heating the system maintains the zone between 70 F and 66 F. Therefore the heating setpoint defines the upper limit of the heating range. Setpoint minus throttling range defines the lower limit of the range. When the zone air temperature is 70 F, the thermostat is calling for minimum heating. When the zone air temperature is 66 F, the thermostat is calling for maximum heating. Between 70 F and 66 F the call for heating increases in proportion to zone temperature.

When the zone air temperature is between 74 F and 70 F, there is no call for cooling or heating. The zone temperature floats in the deadband between cooling and heating setpoints.

 

[remp]

VSSriram.

Thanks for your reply, so am I correct in saying the summer time design air temperature will be 76 +/- 2 F???

Also what if you want summer and winter tstat set pojt to be the same, is there any problem, no dead band?