Control for forced air heating and/or cooling system

Claim 2

In a forced-air heating or cooling system having a plurality of room thermostats, a plurality of dampers which are automatically controlled individually by said thermostats to regulate the delivery of heated or cooled air to the corresponding rooms, heat exchange means for heating or cooling the air to be supplied to said dampers, and a variable speed fan for passing heated or cooled air from said heat exchange means to said dampers, the improvement which comprises: means for varying the speed of said fan in accordance with the total demand for heated or cooled air from said thermostats.

Claim 3

A system according to claim 1, wherein each damper is fully opened when the corresponding thermostat demands heated or cooled air and is fully closed when the corresponding thermostat does not demand heated or cooled air.

Claim 4

A system according to claim 1, wherein said last-mentioned means comprises: means for interrogating said thermostats individually in succession to provide corresponding demand signals if the interrogated thermostat senses the need for heated or cooled air; and means responsive to said demand signals to set the fan speed in accordance with the accumulated total of said demand signals.

Claim 5

A system according to claim 3, and further comprising means operable by at least one of the thermostats to produce more than one demand signal whenever said thermostat, when interrogated, senses the need for heated or cooled air there.

Claim 6

A system according to claim 3, and further comprising means responsive to each thermostat to produce a no-demand signal which reduces said total demand when that thermostat senses that the desired air temperature has been reached.

Claim 7

A system according to claim 5, wherein said means to set the fan speed comprises: bidirectional stepping means operated in one direction by said demand signals and operated in the reverse direction by said no-demand signals; and a motor controller operated by said stepping means to control the speed of the fan in accordance with the setting of said stepping means.

Claim 8

A system according to claim 3, wherein said means for interrogating the thermostats to provide demand signals comprises: a switch operated individually by each thermostat in accordance with whether the desired air temperature has been reached there; a relay operated by said switch when said thermostat is demanding heated or cooled air; and means responsive to the operation of said relay to a. open the damper for that thermostat''s heating or cooling zone, and b. produce a demand signal for increasing the fan speed, and c. discontinue said demand signal after a brief time delay.

Claim 9

A system according to claim 7, and further comprising: an additional relay operated by said switch when said thermostat is not demanding heated or cooled air; and means responsive to the operation of said last-mentioned relay to a. close the damper for the thermostat''s heating or cooling zone, and b. produce a signal for reducing said accumulated total of demand signals so as to reduce the fan speed accordingly, and c. discontinue said last-mentioned signal after a brief time delay.

Claim 10

A system according to claim 8, and further comprisiNg means operable by at least one of the thermostats to produce more than one demand signal or no-demand signal in accordance with whether said thermostat senses the need for heated or cooled air there.

Claim 11

In a forced-air heating or cooling system having a plurality of room thermostats, a plurality of dampers which are automatically controlled individually by said thermostats to regulate the delivery of heated or cooled air to the corresponding rooms, heat exchange means for heating or cooling the air to be supplied to said dampers, and a variable speed fan for passing heated or cooled air from said heat exchange means to said dampers, the improvement which comprises: means for producing demand signals from those thermostats which demand heated or cooled air; and electrically operable means for controlling the fan speed in accordance with the accumulated total of said demand signals.

Claim 12

In a forced-air heating or cooling system having a plurality of room thermostats, a plurality of dampers which are automatically controlled individually by said thermostats to regulate the delivery of heated or cooled air to the corresponding rooms, heat exchange means for heating or cooling the air to be supplied to said dampers, and a variable speed fan for passing heated or cooled air from said heat exchange means to said dampers, the improvement which comprises: means for producing demand signals from those thermostats which demand heated or cooled air; and electrically operable means for controlling the fan speed in accordance with the accumulated total of said demand signals.

Claim 13

A system according to claim 10, wherein said last-mentioned means comprises reversible stepping means for totalling said demand signals, and an electrical controller operated by said stepping means and controlling the speed of the fan motor.

Claim 14

A system according to claim 10, wherein said means for producing demand signals from the thermostats includes means providing time separation of the demand signals from the different thermostats.

Claim 15

A system according to claim 12, and further comprising means operable by each thermostat to produce a signal, whenever that thermostat does not demand heated or cooled air, for reducing said accumulated total of demand signals.

Claim 16

In a forced-air heating or cooling system having a plurality of discrete area thermostats, separate ducts leading to the different discrete areas to be heated or cooled, a damper for each duct movable between fully-open and fully-closed positions under the control of the corresponding thermostat, and means for varying the flow rate of heated or cooled air delivered to said ducts the improvement which comprises: means for interrogating the thermostats individually in succession and for controlling said flow rate varying means to deliver heated or cooled air in accordance with the present total demand of all the thermostats.

Claim 17

In a forced-air heating or cooling system having a plurality of discrete area thermostats, separate ducts leading to the different discrete areas to be heated or cooled, a damper for each duct movable between fully-open and fully-closed positions under the control of the corresponding thermostat, and means for varying the flow rate of heated or cooled air delivered to said ducts the improvement which comprises: means for interrogating the thermostats individually in succession and for controlling said flow rate varying means to deliver heated or cooled air in accordance with the present total demand of all the thermostats.

Claim 18

A system according to claim 14, wherein said last-mentioned means comprises: timing means for causing the thermostats to be interrogated individually in succession to provide corresponding demand signals according to whether or not each interrogated thermostat demands heated or cooled air; and means for accumulating the total of said demand signals and for regulating the flow rate of heated or cooled air delivered to the ducts in accordance with said accumulated total.

Claim 19

In a forced-air heating or cooling system having a plurality of room thermostats, separate forced-air ducts for the different rooms, a damper for each duct movable under the control of the corresponding thermostat between fully-open and fully-closed positions, and a variable speed fan for passing heated or cooled air to the ducts, the improvement which comprises: a controller for setting the fan speed at any of several discrete selected values; electrically operated means for operating said controller digitally; binary switch means operated by each thermostat to provide either a deman signal or a no-demand signal, in accordance with whether the air temperature at that thermostat is at the value set by that thermostat; and relay means operated by each binary switch means to produce digital signals for operating said electrically operated means digitally.

Claim 20

In a forced-air heating or cooling system having a plurality of room thermostats, separate forced-air ducts for the different rooms, a damper for each duct movable under the control of the corresponding thermostat between fully-open and fully-closed positions, and a variable speed fan for passing heated or cooled air to the ducts, the improvement which comprises: a controller for setting the fan speed at any of several discrete selected values; electrically operated means for operating said controller digitally; binary switch means operated by each thermostat to provide either a deman signal or a no-demand signal, in accordance with whether the air temperature at that thermostat is at the value set by that thermostat; and relay means operated by each binary switch means to produce digital signals for operating said electrically operated means digitally.

Claim 21

A system according to claim 16, wherein said electrically operated means is a bidirectional relay which is stepped a single increment in one direction in response to each demand signal and is stepped a single increment in the opposite direction in response to each no-demand signal.

Claim 22

A system according to claim 17, and further comprising means for correcting said bidirectional stepping relay to eliminate possible erRors therein when it is at either extreme operating position.

Claim 23

A system according to claim 16, wherein said relay means operated by at least one of said thermostat-operated binary switch means produces more than one demand signal when that thermostat is calling for a temperature change and produces the same number of no-demand signals when the air temperature at that thermostat reaches the value for which it is set.

Claim 24

A system according to claim 16, wherein said relay means comprises, for each thermostat, a corresponding first relay operated by the respective binary switch means to produce a demand signal when that thermostat calls for a temperature change and a corresponding second relay operated by the respective binary switch means to produce a no-demand signal when that thermostat is satisfied, and further comprising program timer means for enabling said first relays individually in succession to be operated by the respective thermostat-operated binary switch means to provide corresponding demand signals, and means for enabling all of said second relays continuously to be operated by the respective thermostat-operated binary switch means to provide corresponding no-demand signals.

Claim 25

A system according to claim 6, wherein said stepping means has ''''up'''' stepping means for stepping it in said one direction and ''''down'''' stepping means for stepping it in said opposite direction, and further comprising a set of normally-closed contracts in series with said ''''up'''' stepping means, means for opening said normally-closed contacts when said stepping means reaches a predetermined value in said one direction, a set of normally-open contacts in series with said ''''down'''' stepping means, and means for closing said normally-open contacts when said stepping means reaches a predetermined value in said opposite direction.