US2615634A

US2615634A - Furnace control device

Info

Publication number: US2615634A
Application number: US187863A
Authority: US
Inventors: Jr Frank Harbin
Original assignee: HOME FURNACE CO
Current assignee: HOME FURNACE CO
Priority date: 1950-10-02
Filing date: 1950-10-02
Publication date: 1952-10-28
Anticipated expiration: 1969-10-28

Description

Oct. z8, 1952 Filed Oct. 2. 1950 F. HARBIN, JR

FURNACE CONTROL DEVICE 2 SHEETS-SHEET l.

Fem

4'FRANK HARMN, JP..

)www M r Avvomsvs Oct. 28, 1952 F. HARBIN, JR 2,615,534

l FURNACE CONTROL DEVICE Filed oct. 2. 195o 2 SHEETS-Smm 2 Room 5 nveuron F1a. YKANK HAnsm., Jn.

s (xiv-Maf (hm-MW Patented ct. 28, 1952 Frank Harbin, Jr., Holland, Mich.,fja'ssign'or to Home Furnace`Company, Holland, Mich., a cor- 'poration 'of Michigan Application'October 2, 1950, Serial No. 187,863

2 Claims. 1

This invention relates to furnace-ccntrols and more particularly to the controls for warm air furnaces used `to heat residences. It is adapted to be applied to furnaces having different tyrxes of yburners such as gas or fuel oil and Ait maybe usedwith the so-called gravity ow type of furnace in which the ow of air from the furnace to the room is caused by gravity or it may be used With the forced air circulation vtype of furnace in which a fan is used to induce thecirculation.

The object-of the device is to cause a more constant circulationof air from the furnace into y'the room so that the v-air in the room will not long remain motionless and stagnant.

To accomplish this result in a gravity flow furnace the furnace is prevented from becoming cold after the room temperature has reached the de'- sired normal degree which is variable but which may be arbitrarily set for the purpose of this -description at 70. After'the room temperature has reached the normal 70 the burner of the yfurnace is controlled to maintain it at moderate ywarmth so that it will induce the vgravity lflow of -air into the room and this moderate vwarmth of the furnace, which maybe arbitrarily `stated as 100, is maintained until the room 'temperature has risen slightly above the Anormal 70 to a temperature which We may state as '71 and at this point the furnace burner stops operation until .the room temperature drops below '71 when ythe A'furnace burner will again operate to raise the furnace temperature to 100". And when the room temperature drops belowgthe normal 70 the furnace will gc into full operation raising itstemperature considerably above 100 to raise the room temperature to normal.

In a forced aircirculation system using a fan to-circulate the air the same control of the burner is usedas above explained for the gravity system but in this forced air circulation a two speed fan may be used and Vthe operation of the fan lis controlled so that when the room temperature is below 70" the fan operates at high` speed but when the .temperature reaches and rises above the normal 70 the fan will be automatically controlled to operate at lowspeed and this low speed operation of the Ifan continues at all room temperatures above 70 until they furnace temperature drops to or below substantially room temperature.

.For amore complete and detailed understanding of the invention reference is made to the accompanying drawings, in which,

Fig. l1 vis a diagram illustrating the electrical connections and various `instruments which may be used in a forced circulation system.

Fig. J2 `is -a like diagram of the device adapted fora gravity ow system. l

Fig. 3 is a sectional view on the line "3-1 ol' Fig. 5 illustrating the thermostatic switch deviceI controlled'by the furnace Yjacket temperature' 'and adapted for the forced circulation system of Fig. 1.

Eig. 4 is a like section on the line v3-4 f Fig. 5 showing Athe jacket temperature controlledthermostatic switch adapted for the gravity flo'w system of Fig. 2'.

Fig. 5 is an elevation of the thermostatic device used in the furnace jacket, its mechanism being' that of ither'lig or'Fig. 4, and c Fig. 6 is a diagrammatic illustration f Jthe' room thermostat used vin either the forced circulation or gravity flow system.

yLike reference numbers refer to 'like ,parts in all of the-gures- Referring now to Fig. 'v2' which is a dag'ramof the gravity 4circulation system in which the air will not circulate through the' heatings'ystem and into the `room to any extent, unless the 'fur'- nace temperature is .higher .than the room teper'ature. The furnace burner is controlled an .electrically operated fuel valve `'l whichp'referably isfopened when energizedl and closed when de-energi'zed. yThe burner isv of the single lStage type, that is, it has only one stage of operation. It is either 'full on or off. A room thermostat generally indicated as 2 is located lin rthe rooin and it is provided with independently adjustableelctrical contacts 3 and '4. IThe circuitis opened or closed through these contacts by a thermostatically operated contact member 5. The contact member r5 is herein illustrated as a single member but it may consist of two separate Contact members although it is preferable that whether the contact member be single or double .itshalll be operated vby a single thermostatic element Aly which is herein shown as a coiled bimetal-strip. however different thermostatic elements -may -be substituted for that shown. The device is-.adjustedso that circuit is .broken at the contact v-3 when theroom temperature reaches normalfsuch as .70 and `the circuit is broken at the contact-V when .the room Atemperature has lrisen slightly above normal, such as 71. Itis to be -understood that these temperatures are given as arbitrary examples and .may be altered by adjustment-of the thermostat.

` The furnace jacket 'l is provided with the jacket thermostat 8A which may be of any Vconventional construction. That herein shown comprises a shaft Sprojectingin'to the furnace jacket and Shaving coiled about it a bimetal strip l0 3 which is connected to the shaft 9 at one end and to the fixed body of the thermostat at the other end, Changes of temperature in the furnace jacket will affect the thermostatic element l to cause slight rotation of the shaft 9.

The jacket thermostat is provided with a head which for this gravity system contains two switches l2 and I3 as illustrated in Fig. 4. These switches are operated to open or close their respective circuits by cams |4 and I5 each adjustably mounted upon a disk I6 attached to the shaft 9 and oscillated thereby in either direction with changes of temperature in the furnace jacket. The cam I4 which actuates the switch |2 is adjusted to break its circuit when the jacket temperature reaches a high limit such as 250. The cam |4 is of such design that it will not break the circuit at the switch |2 at any low jacket temperature. The cam I which actuates the switch I3 is adjusted to break its circuit when the jacket temperature reaches a moderate temperature, such as 100, which is sufliciently higher than the room temperature to maintain the gravity air fiow. This switch I3 is likewise closed at all temperatures below 100.

Electric current to operate the fuel valve I and controlled by the various switches is supplied by a transformer |'I which is supplied by current from a conventional source through the conductors I8. A conductor IS connects the room thermostat contact 3 with the jacket thermostat switch I 2 and the conductor 20 connects the room thermostat contact 4 with the jacket thermostat switch I3. Both of the jacket switches I2 and I3 are connected to the fuel valve by the conductor 2| and the conductor 22 leads from the fuel valve through the transformer I'I to the contact breaker 5 of the room thermostat.

Now when the room temperature is below 70 and the furnace jacket temperature is below 100 all of the switches will be closed and the fuel valve will be energized and opened so that the re will burn to heat the furnace. As the jacket temperature increases and rises above 100 the switch I3 will be opened but inasmuch as this controls only one of the circuits to the fuel valve it will not by itself stop operation of the burner. When the room temperature reaches 70 the current through the conductor I9 will be broken at the Contact 3 which will open the other circuit to the fuel valve de-energizing it and causing it to close and cease burning of the furnace.

Under the foregoing conditions the jacket temperature may be considerably above 100 and although the furnace is not operating it is sufficiently warm to cause circulation of air into the room. As the furnace gradually cools and the jacket temperature drops below 100, if the room temperature is not above 71, the switch I3 will be closed and as the circuit is still maintained through the contact 4 and the fuel valve will again open and cause operation of the furnace, thus maintaining the jacket temperature at substantially 100 unless the room temperature rises above 71 at which point the circuit through the conductor 20 will be broken at the contact 4 and even with the switch I3 closed the fuel valve cannot become energized.

By the foregoing means and as long as the room temperature is above 70 the furnace will be kept sufficiently warm to cause air circulation unless the room temperature rises above 71 and then the furnace becomes completely inoperative. When the room temperature drops below 70 both conductors |9 and 20 will be closed at the 4

contacts

3 and 4 and full operations of the furnace will begin.

Referring to Fig. 1 which is a diagram of the forced air circulation system, the furnace is provided with the same type of fuel valve I and the same type of room thermostat 2 is used in the room. In addition a fan 25 is provided in the air circulatory system. The same type of furnace jacket thermostat is provided in this system excepting that it is provided with a third switch 26 which controls operation of the fan. A third adjustable cam 21 is mounted on the disk |6 which operates the fan switch 26. This arrangement is illustrated in Fig. 3.

The fan may be driven by a two speed electric motor 25. It is customary to operate the fan motor on high voltage current such as 11C-volt and the fuel valve is preferably operated by a lower voltage current such as 25-vo1t. For that reason the motor is connected directly into the 11G-volt system and the lower voltage for the fuel valve system is provided by the like transformers 28 two of which are shown but all of the low voltage current may be supplied by one transformer if desired. This system also includes a relay switch generally indicated as 29 provided with two

switch levers

30 and 3| simultaneously actuated by a magnet 32. These switch levers 30 and 3| are moved to the solid line position when the magnet 32 is energized and dropped to the dotted line position when the magnet is de-energized. The relay includes the

contacts

33 and 34 which coact with the arm 30 and the

contacts

35 and 36 which coact with the arm 3|.

The high voltage current is carried by the conductors 40 and 4I, conductor 4| being connected directly to the ground post of the two speed fan motor 25. The conductor 40 is joined with the fan switch 26 by the conductor 42 and the conductor 43 leads from the switch 26 to the relay switch lever 3|. The conductor 44 leads from the relay contact 35 to the high speed post of the motor 25 and the relay contact 36 is connected by the conductor 45 with the low speed post of the motor 25. By this means the fan motor is operated at high speed when the magnet 32 is energized and the arm 3| lifted and the fan motor is operated at low speed when the magnet is de-energized and the lever 3| is lowered as long as fan switch 26 is in contact.

The

conductors

46, 41 and 48 form a circuit for the magnet 32 through the transformer 28 and the room thermostat contact 3 and the thermostat member 5 thereof when the room temperature is below 70. When the magnet 32 is energized the relay lever 30 is raised into engagement with the contact 33 and circuit to the fuel valve is completed through the conduit 50, the jacket thermostat switch I2, and the conduits 5|, 52 and 53 through the transformer 28. When the room temperature rises above 70, but is below 71, the relay magnet 32 is de-energized and the lever 30 drops against the contact 34 and if the furnace jacket temperature is below the fuel valve is energized through the conductor 50, the jacket thermostat switch |3, the conduit 55, through the room thermostat, the conduit 48, the jumper 56, and the

conduits

52 and 53.

Therefore in this forced air circulation when the room temperature is below 7 0 the fuel valve is open so that the furnace is in full operation and the fan motor is operated at high speed. But when the room temperature reaches the normal 70 the circuit is broken at the contact 3 in the room thermostat and the relay magnet is cie-energized. The relay levers then drop and close the circuits to operate the fan motor at low speed and if the furnace jacket temperature is above 100 the circuit to the fuel valve is broken by the jacket thermostat switch I3. 1f the jacket temperature drops below 100 while the room temperature is below 71 the jacket switch I3 will close and open the fuel valve to raise the furnace temperature. However when the room, temperature rises above 71o the circuit is broken at the contact l and the fuel valve will not open no matter how low the furnace temperature drops and if the furnace temperature falls below substantially room temperature the jacket thermostat switch 26 will open to stop operation of the fan motor.

Therefore it will be seen that this system, applied to either the gravity flow circulation or the forced air-circulation system, will operate to raise the room temperature to a normal 70 and will also maintain an air circulation through the system at a lower temperature and reduced flow when the room temperature is above 70 but below 71. When the room temperature rises above 71 the heating system ceases operation completely so that the room temperature will not be raised to an undesirable point and at this temperature the lack of air circulation in the room is not noticeable.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming Within their scope.

I claim:

1. The combination with a room heating system having a furnace with an electrically controlled single stage burner therefor, and a twospeed electric air circulating fan, of a control device comprising a room thermostat having two electric contact breakers operated by a thermostatic element to open and close at different temperatures, a furnace temperature controlled thermostat having two electric contact breakers operated by a thermostatic element to open and close at different temperatures to control the operation of the burner, said furnace thermostat also having a third contact breaker operated by the said thermostatic element to control operation of the fan, a single relay switch having two synchronously moving switch members, each making and breaking two circuits, one of said switch members being in the burner control circuit and the other in the fan control circuit, the lower temperature room thermostat contact breaker controlling energization of said relay switch which, when energized, closes the circuit through the higher temperature furnace thermostat circuit breaker to operate the furnace burner and also closes the high speed fan circuit through the furnace thermostat fan contact breaker, said relay switch, when deenergized, closes the circuit through the lower temperature furnace thermostat circuit breaker to operate the furnace burner, and also closes the low speed fan circuit through the furnace thermostat fan circuit breaker, the higher temperature room thermostat circuit breaker being in series circuit with the lower temperature furnace thermostat circuit breaker.

2. The elements of claim 1 in which deenergization of the relay switch throws the higher temperature room thermostat circuit breaker and the lower temperature furnace thermostat circuit breaker in series circuit with the higher temperature furnace thermostat circuit breaker.

FRANK HARBIN, J R.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS