Electric heating system circuit for sequentially energizing a plurality of heating elements

Claim 2

A circuit for a heating system comprising a plurality of electric heating elements; means including a motor for circulating fluid to be heated; a plurality of at least three relays each having a heat motor and at least a first and a second switch each of which is closeable by energizing the respective heat motor for at least a predetermined time duration; the first switch of a first relay of the plurality of relays controlling the motor of the fluid circulating means; the first switch of each of the relays following the first relay controlling the respective heating elements; the second switch of each relay, except a last relay of the plurality of relays, controlling the energization of the heat motor of the next relay; a third switch of a second relay of the plurality of relays, the third switch being a double-pole switch and being connected so that in one position it connects the heat motor of the first relay to the second switch of the last relay and in the other position it energizes the heat motor of the first delay; a thermostatic switch connected in a first series circuit with the heat motor of the first relay through the second switch of the last relay and the third switch of the second relay to energize the first relay to commence heating of the heating elements and in a second series circuit with the heat motor of the second relay and the second switch of the first relay to deenergize the second relay to commence de-energizing of the heating elements; and the second switch of the last relay being a double pole switch and connected in one position in the first series circuit between the third switch of the second relay and the thermostatic switch and connected in the other position in a by-pass series circuit with the heat motor of the first relay to by-pass the thermostatic switch to maintain the first relay energized when the last relay is energized.

Claim 3

A circuit for a heating system as claimed in claim 1 wherein there are power lines to supply power to the heating system, there is a transformer having a secondary winding and a primary winding connected across said power lines, said heating elements are connected in series with their respective switches across said power lines, said second switches energize the heat motors of said next relays by connecting them across the secondary of the transformer, and the first and second series circuits with the heat motor of said first relay are connected across the secondary of the transformer.

Claim 4

A circuit for a heating system as claimed in claim 1 wherein each of said heat motors includes a pair of elongated bimetal elements each secured at one end and free at its other end, each bimetal element having a transverse curvature so as to be snap-acting at a predetermined temperature, a heater wire to heat both of said pair of bimetal elements simultaneously, and a pair of actuators in contact with the free end of each bimetal element to transmit the movement of said bimetal elements to the respective first and second switches of each relay.

Claim 5

A circuit for a heating system comprising a plurality of electric heating elements; means including a motor for circulating fluid to be heated; a plurality of relays including at least a first relay, a second relay, and a last relay, each relay having at least first and second switches and a heat motor for operating the first and second switches after a predetermined duration of energization of the heat motor, said first switch of the first relay controlling said motor of the circulating means; said first switches of the plurality of relays following the first relay controlling respective heating elements of the plurality of heating elements; said second switch of each of the plurality of relays, except the last relay, being normally open and connected in series with the heat motor of the next relay; said second switch of the last relay including a normally closed contact, a normally open contact and a common contact for engaging the normally closed contact when the last relay is unoperated and for engaging the normally open contact when the last relay is operated; said second relay having a third switch which includes a normally closed contact, a normally open contact, and a common contact for engaging the normally closed contact when the second relay is unoperated and for engaging the normally open contact when the second relay is operated; a thermostatic switch connected in series with the normally closed contact and the common contact of the second switch of said last relay, the normally closed contact and the common contact of the third switch of the second relay, and the heat motor of the first relay to energize the first relay to initiate sequential energization of the motor of the fluid circulating means and the heating elements; circuit connection means from the thermostatic switch in series with the heat motor of the second relay and the normally open second switch of the first relay to energize the second relay when the second switch of the first relay closes and to initiate de-energization of the plurality of relays when the thermostatic switch opens; and circuit connection means in series with the normally open contact and the common contact of the second switch of the last relay, the normally closed contact and the common contact of the third switch of the second relay, and the heat motor of the first relay to maintain the first relay energized when the second switch of the last relay is operated, said normally open contact of the third switch of the second relay connected to the normally open contact of the second switch of the last relay.

Claim 6

A circuit for a heating system comprising a plurality of electric heating elements; means including a motor for circulating fluid to be heated; a plurality of relays including at least a first relay, a second relay, and a last relay, each relay having at least first and second switches and a heat motor for operating the first and second switches after a predetermined duration of energization of the heat motor, said first switch of the first relay controlling said motor of the circulating means; said first switches of the plurality of relays following the first relay controlling respective heating elements of the plurality of heating elements; said second switch of each of the plurality of relays, except the last relay, being normally open and connected in series with the heat motor of the next relay; said second switch of the last relay including a normally closed contact, a normally open contact and a common contact for engaging the normally closed contact when the last relay is unoperated and for engaging the normally open contact when the last relay is operated; said second relay having a third switch which includes a normally closed contact, a normally open contact, and a common contact for engaging the normally closed contact when the second relay is unoperated and for engaging the normally open contact when the second relay is operated; a thermostatic switch connected in series with the normally closed contact and the common contact of the second switch of said last relay, the normally closed contact and the common contact of the third switch of the second relay, and the heat motor of the first relay to energize the first relay to initiate sequential energization of the motor of the fluid circulating means and the heating elements; circuit connection means from the thermostatic switch in series with the heat motor of the second relay and the normally open second switch of the first relay to energize the second relay when the second switch of the first relay closes and to initiate de-energization of the plurality of relays when the thermostatic switch opens; and circuit connection means in series with the normally open contact and the common contact of the second switch of the last relay, the normally closed contact and the common contact of the third switch of the second relay, and the heat motor of the first relay to maintain the first relay energized when the second switch of the last relay is operated, said normally open contact of the third switch of the second relay connected to the normally open contact of the second switch of the last relay.

Claim 7

A circuit as claimed in claim 4 including a second stage thermostatic switch connected in series with the heat motor of the last relay.

Claim 8

A circuit for a heating system comprising first, second, third, fourth, fifth and sixth heating elements; a blower motor; power lines adapted to be connected to a source of power; a transformer having a primary winding and a secondary winding, the primary being connected across said power lines; first, second, third and fourth relays each having a heat motor and first and second single pole, single throw, power switches which are sequentially closeable by energizing the respective heat motor for at least predetermined first and second durations; said first power switch on each of said relays and said second power switch on said first and said fourth relays being connected in respective series circuits with the respective first, second, third, fourth, fifth and sixth heating elements, each series circuit connected across the power lines so that said power switches control the power to the heating elements; said blower motor being connected in parallel with said first heating element connected in series with said first power of the first relay so that said first power switch of the first relay also controls the blower motor; said first, second, and fourth relays each having a control switch actuated by the respective heat motors, the control switch on the first relay being single throw, single pole, the control switch on the second and fourth relays being single pole, double throw, and having a contact arm, a normally closed contact, and a normally open contact; a thermostatic switch; said thermostatic switch connected in a series circuit with the normally closed contact of the control switch of the fourth relay, the contact arm of the control switch of the fourth relay, the normally closed contact of control switch of the second relay, the contact arm of the control switch of the second relay, and the heat motor of the first relay, in the named order, between first and second ends of the secondary winding of the transformer, the first end of the secondary winding joined to one side of the thermostatic switch; said control switch of the first relay connected in series with the heat motor of the second relay and with the thermostatic switch, in the named order, between the second and first ends of the secondary winding of the transformer; said second power switch on the second and third relays being connected in series with the respective heat motors of the third and fourth relays across the secondary winding of the transformer to control the operation of the third and fourth relays; and said normally open contacts of the control switches of the third and fourth relays being connected to the first end of the secondary winding.

Claim 9

A circuit for a heating system comprising first, second, third, fourth, fifth and sixth heating elements; a blower motor; power lines adapted to be connected to a source of power; a transformer having a primary winding and a secondary winding, the primary being connected across said power lines; first, second, third and fourth relays each having a heat motor and first and second single pole, single throw, power switches which are sequentially closeable by energizing the respective heat motor for at least predetermined first and second durations; said first power switch on each of said relays and said second power switch on said first and said fourth relays being connected in respective series circuits with the respective first, second, third, fourth, fifth and sixth heating elements, each series circuit connected across the power lines so that said power switches control the power to the heating elements; said blower motor being connected in parallel with said first heating element connected in series with said first power of the first relay so that said first power switch of the first relay also controls the blower motor; said first, second, and fourth relays each having a control switch actuated by the respective heat motors, the control switch on the first relay being single throw, single pole, the control switch on the second and fourth relays being single pole, double throw, and having a contact arm, a normally closed contact, and a normally open contact; a thermostatic switch; said thermostatic switch connected in a series circuit with the normally closed contact of the control switch of the fourth relay, the contact arm of the control switch of the fourth relay, the normally closed contact of control switch of the second relay, the contact arm of the control switch of the second relay, and the heat motor of the first relay, in the named order, between first and second ends of the secondary winding of the transformer, the first end of the secondary winding joined to one side of the thermostatic switch; said control switch of the first relay connected in series with the heat motor of the second relay and with the thermostatic switch, in the named order, between the second and first ends of the secondary winding of the transformer; said second power switch on the second and third relays being connected in series with the respective heat motors of the third and fourth relays across the secondary winding of the transformer to control the operation of the third and fourth relays; and said normally open contacts of the control switches of the third and fourth relays being connected to the first end of the secondary winding.

Claim 10

A circuit claimed in claim 6 including a second stage thermostatic switch connected in series with the heat motor of the third relay.