Information
-
Patent Grant
-
6465764
-
Patent Number
6,465,764
-
Date Filed
Wednesday, August 30, 200024 years ago
-
Date Issued
Tuesday, October 15, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Michael Best & Friedrich LLP
-
CPC
-
US Classifications
Field of Search
US
- 219 494
- 219 501
- 219 508
- 219 519
- 219 497
- 392 450
- 392 449
- 392 454
- 324 73 R
- 324 505
- 324 547
-
International Classifications
-
Abstract
A water heater having a water tight tank (10) with a cold water inlet (14) and a hot water outlet (16). First and second heating elements (24, 26) are mounted in the upper and lower portions of the tank (10). A controller is provided for energizing element (24) to heat water in the upper portion of tank (10) until the temperature of the water in the upper portion of tank (10) reaches a preset temperature, at which time, the element (24) will be de-energized. The controller is adapted to energize element (26) when element (24) is de-energized. The controller is further adapted to de-energize element (26) and at the same time energize element (24) when the temperature of the water in the lower portion of the tank reaches a preset temperature.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO MICROFICHE APPENDIX
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to an electric water heater and more particularly to a control system for an electric water heater having an upper and a lower heating element.
BRIEF SUMMARY OF THE INVENTION
The water heater control system operates to cycle the energization of the upper and lower heating elements. The upper element is initially energized to heat the water in the upper portion of the tank to a predetermined set temperature at which time the upper element will be de-energized and the lower element will be energized. The lower element then heats the water in the lower portion of the tank to a predetermined set temperature, at which time the lower element will be de-energized and the upper element will again be energized. The sequence of heating the water in the upper and lower portions of the tank is then repeated.
Another feature of the control system is the prevention of a “dry fire ” condition, i.e., energization of the heating elements without water in the water heater tank.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a partially schematic/wiring diagram for the programmable control for electric water heater of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to
FIG. 1
, the electric water heater of the present invention is comprised of a water tank
10
, a tank jacket
12
, a tank jacket base
11
and a jacket top
13
.
The water heater tank
10
has a cold water inlet
14
and a hot water outlet
16
, both mounted in jacket top
13
. A dip tube
18
connected to cold water inlet
14
extends downwardly inside tank
10
to the open outlet end
20
of the dip tube
18
. In use when heated water is drawn out of the top portion of the tank
10
through outlet
16
, cold water will be simultaneously drawn into the tank through inlet
14
and dip tube
18
. Cold water flowing downwardly through dip tube
18
will flow out open outlet end
20
of the dip tube into the lower portion of the water heater tank
10
.
The control circuitry and control components for the water heater are shown in FIG.
1
. The control includes an energy cut-off device of conventional design
22
, an upper heating element
24
and a lower heating element
26
mounted inside tank
10
. Upper and lower heat sensors
28
,
30
are mounted on the outer surface of tank
10
. Relays
32
,
34
are provided for controlling the on-off energization of heating elements
24
,
26
. Relays
32
,
34
are mounted exteriorly of the water heater tank.
A 240 VAC to 24 VAC step-down transformer (not shown) is mounted exteriorly of the water heater tank. In a preferred embodiment, the step-down transformer provides 240 volts AC to heating elements
24
and
25
under the control of relays
32
and
34
.
Relay
32
has a winding
32
a
and a movable switch arm
40
. When winding
32
a
is de-energized, arm
40
will be in contact with contact
39
and when winding
32
a
is energized, arm
40
will be moved out of contact with contact
39
and into contact with contact
41
.
Relay
34
has a winding
34
a
and a movable switch arm
42
. When winding
34
a
is de-energized, arm
42
will be in contact with contact
43
. When winding
34
a
is energized, arm
42
will be moved out of contact with contact
43
.
Conductors
36
,
36
carry 24 volts AC from the step-down transformer to winding
32
a
of relay
32
through control unit A.
Conductors
38
,
38
carry 24 volts AC from the step-down transformer to winding
34
a
of relay
34
through control unit B. Relay
32
has a normally closed movable switch arm
40
and relay
34
has a normal open switch arm
42
.
Energy cut-off device
22
receives 240 volts AC through conductors
44
,
44
. The 240 volts AC fed into energy cut-off unit
22
is fed to heating units
24
,
26
through conductors
46
,
48
.
The 240 volts AC fed to heating unit
24
is fed back to energy cut-off unit
22
through conductor
50
, relay switch arm
40
and conductor
52
. The 240 volts AC fed to heating unit
26
is fed back to energy cut-off unit
22
through conductor
54
, relay switch arm
42
, conductor
56
, relay arm
40
and conductor
52
.
OPERATION
A typical sequence of operation upon a call for heat in the water heater is as follows.
At the start of the sequence, relay switch arms
40
,
42
will be in the positions shown in solid lines in FIG.
1
.
With relay switch arm
40
in the
FIG. 1
position, upper heating element
24
will be energized. When the water in the upper portion of tank
10
heats to 120° F. (or some other temperature setting), sensor
28
will actuate control unit A, which, in turn, will energize winding
32
a
of relay
32
. The energization of winding
32
a
will move relay switch arm
40
from contact with contact
39
(solid line) into contact with control
41
(dotted line) to thereby de-energize element
24
. The movement of switch arm
40
into contact with contact
41
will electrically connect conductors
52
and
56
to each other, thus causing heating element
26
in the lower portion of the tank to be energized.
Lower sensor
30
will then take over control of the water heater as lower element
26
heats the water in the lower portion of tank
10
.
When the water temperature in the lower portion of tank
10
reaches 120° F., sensor
30
will signal control unit A to energize winding
34
a
of relay
34
to thereby move switch arm
42
to its open position (shown in dotted lines). Heating element
26
will thereby be de-energized. Also, when winding
34
a
of relay
32
is energized, control unit A will operate to de-energize winding
32
a
of relay
32
. This will allow switch arm
40
of relay
32
to move back into contact with contact
39
to thereby energize heating element
24
.
When the water temperature in the lower portion of the tank falls below 120° F., control unit A will de-energize winding
34
a
of relay
34
to thereby allow switch arm
42
of relay
34
to be returned to the
FIG. 1
solid line position. The heating sequence described above will then be repeated.
Another feature of the subject control system described above is the prevention of a “dry fire ” condition, Le., energization of the heating elements
24
,
26
without water in tank
10
. This is a condition that may occur upon original installation of the water heater wherein the installer inadvertently fails to fill tank
10
with water before connecting the water heater to a source of electrical energy.
If, for example, upon the initiation of the heating cycle described above, the temperature sensed by sensors
28
,
30
increases at a rate greater than 3° F. per minute, control units A and B will operate to open relays
32
,
34
to thereby shut off current to elements
24
,
26
.
While the invention herein has been shown and described in what is presently conceived to be the most practical preferred embodiment, it will be obvious to one of ordinary skill in the art that many modifications may be made thereof within the scope of the invention, which scope is not to be limited except by the appended claims.
Claims
- 1. A water heater comprising:(1) a water-tight tank (10); (2) said tank (10) having a cold water inlet (14) and a hot water outlet (16); (3) a first electrical heating element (24) mounted in an upper portion of said tank (10); (4) a second electrical heating element (26) mounted in a lower portion of said tank (10); (5) a first temperature sensor element (28) mounted on the outer surface of said tank (10); (6) a second temperature sensor element (30) mounted on the outer surface of said tank (10); (7) a first relay (32) mounted outside of said tank (10) having a first switch arm (40) and a winding (32a), said first switch arm (40) movable between a first position and a second position; (8) a second relay (34) mounted outside said tank (10) having a second switch arm (42) and a winding (34a), said second switch arm (42) movable between a first closed position and a second open position; (9) a source of high AC voltage connected to said first (24) and second (26) heating elements; (10) a source of low AC voltage connected to said windings (32a and 34a) of said first and second relays (32, 34) respectively; and (11) an electrical control unit (A) electrically connected to said first temperature sensor element (28) and said first relay winding (32a), said control unit (A) also connected to said second temperature sensor element (30) and said second relay winding (34a); (12) said first relay (32) adapted to energize said first electrical heating element (24) when said first relay winding (32a) is in a de-energized condition; (13) said first electrical heating element (24) adapted to actuate said control unit (A) to thereby de-energize said first electrical heating element (24) when the water in the upper portion of said tank (10) reaches a preset temperature; (14) said first relay (32) is further adapted to energize said second electrical heating element (26) when said first arm (40) of said relay is actuated to move from its first position to its second position; and (15) said second temperature sensor element (30) adapted to actuate said control unit (A) to energize said second relay winding (34a) of relay (34) to thereby move said second switch arm (42) to its open position to thereby de-energize said second electrical heating element (26) when the temperature in the lower portion of the tank reaches said preset temperature; wherein said control unit (A) is adapted to sense a temperature rise in the tank (10) at an abnormally high rate, at which time the control unit (A) will operate to open said first and second relays (32, 34) to thereby shut off current to said first and second electrical heating elements (24, 26).
- 2. A water heater according to claim 1 in which said high AC voltage is 240 volts AC and said low AC voltage is 24 volts AC.
- 3. A water heater according to claim 1 in which said preset temperature is 120° F.
- 4. A water heater according to claim 1 in which the abnormally high rate is 3° F. or greater per minute.
- 5. A water heater comprising:(1) a water tight tank (10); (2) said tank (10) having a cold water inlet (14) and a hot water outlet (16); (3) a first electrical heating element (24) mounted in an upper portion of said tank (10); (4) a second electrical heating element (26) mounted in a lower portion of said tank (10); (5) control means adapted for energizing said first electrical heating element (24) to heat water in the upper portion of said tank (10) until the temperature of the water in the upper portion of said tank (10) reaches a preset temperature, at which time said first electrical heating element (24) will be de-energized and said second electrical heating element (26) will be energized, said control means further adapted to de-energize said second electrical heating element (26) and at the same time energize said first electrical heating element (24), when the temperature of the water in the lower portion of the tank (10) reaches said preset temperature; wherein said control means is adapted to sense a temperature rise in the tank (10) at an abnormally high rate, at which time the control means will operate to shut off current to said first and second electrical heating elements (24, 26).
- 6. A water heater according to claim 5 in which said control means includes a first temperature sensor (28) mounted in the upper portion of said tank (10) and a second temperature sensor (30) mounted in the lower portion of said tank (10).
- 7. A water heater according to claim 6 in which said control means further includes a control unit (A) controlled alternately by said first temperature sensor (28) and said second temperature sensor (30).
- 8. A water heater according to claim 7 in which said control means further includes a pair of relays (32, 34) controlled by control unit (A).
- 9. A water heater according to claim 7 in which said relays (32, 34) control the energization and de-energization of said heating elements (24, 26) respectively.
- 10. A water heater according to claim 5 in which said preset temperature is 120° F.
- 11. A water heater according to claim 6 in which said control means includes a step-down transformer operable to supply said heating elements (24, 26) with a source of high AC voltage and further operable to supply said temperature sensors (28, 30) with a source of low AC voltage.
- 12. A water heater according to claim 11 in which said high AC voltage is 240 volts AC and said low AC voltage is 24 volts AC.
- 13. A water heater according to claim 9 in which said abnormally high rate is 3° F. or greater per minute.
- 14. A water heater comprising:(1) a water-tight tank (10); (2) said tank (10) having a cold water inlet (14) and a hot water outlet (16); (3) a first electrical heating element (24) mounted in an upper portion of said tank (10); (4) a second electrical heating element (26) mounted in a lower portion of said tank (10); (5) a first temperature sensor element (28) for sensing the water temperature in the upper portion of said tank (10); (6) a second temperature sensor element (30) for sensing the water temperature in the lower portion of tank (10); (7) a first relay (32) for controlling the energization and de-energization of said first temperature sensor element (28); (8) a second relay (34) for controlling the energization and de-energization of said second temperature sensor element (30); (9) an electrical control unit (A) operable in response to electric signals from said first and second temperature sensor elements (28, 30), said control unit (A) operable to cycle the operation of said first and second relays (32, 34) to thereby cycle the energization and de-energization of first and second temperature sensor elements (28, 30); wherein said control unit (A) is adapted to sense a temperature rise in the tank (10) at an abnormally high rate, at which time the control unit (A) will operate to open said first and second relays (32, 34) to thereby shut off current to said first and second electrical heating elements (24, 26).
US Referenced Citations (5)