Intermatic T104-20 Owner's Manual

ELECTRIC
WATER HEATER
TIME SWITCH

BY THE MAKERS OF TIME CONTROLS

The

“LITTLE
GRAY
BOX”

®

HAS EXTERNAL

•

MANUAL OVERRIDE
SWITCH

• EASY TO INSTALL

• MATCH WATER HEATER

OFF TIMES TO PEAK
ENERGY PERIODS OF
YOUR UTILITY TO
REDUCE THEIR
DEMAND

Shown With
External Manual Lever

STEP 1
A. CHECKING:

q Make sure the Time Switch and the water heater
VOLTAGES are the same.

q Make sure your water heater heater rating in WATTS
is not over the maximum capacity of this Time Switch.

q Make sure your water heater is wired with COPPER wire.
Do not connect ALUMINUM wires to the terminals of
this Time Switch. You may wish to consult an electrician
if your existing wires are ALUMINUM.
CAUTION - Disconnect electricity before you attempt to
remove or expose any wiring.

B. PLANNING AND MEASURING:

 Here is how your water heater is wired now, BEFORE
the installation of this Time Switch:

Service
Box

Water
Heater

Figure 1

j SERVICE BOX - Your water heater should have its own

(separate) fuse or circuit breaker in the electrical panel.

k JUNCTION BOX - You may or may not have this

convenience box. It may contain a disconnect switch
and/or receptacle if water heater is cord connected.

l WATER HEATER CONNECTION - This is a rigid or

flexible (metallic or plastic) cable containing 2, 3, or 4
insulated wires of different colors.

m WATER HEATER TERMINAL BOX - This is part of the

water heater where the power supply wires are connected
Here is your modified wiring, AFTER the Time Switch
is installed:

HARD-WIRED CORD AND PLUG CONNECTED

Time
Switch

Figure 2

Water
Heater

Time
Switch

Figure 3

Water
Heater

• Plan a convenient location for the Time Switch, preferably

eye level (also out of reach of small children), and such
that existing cable (Fig. 2 or Fig. 3, Item l) may be utilized.

• Measure the distance n from the Time Switch to Water

Heater Terminal Box m . Also measure distance l
from Time Switch to Junction Box if existing cable (Fig 2, Item

l ) is too short. Allow for slack and 6 inches of hook-up
leads at each end to facilitate wiring connections.

C. MATERIALS YOU NEED
If your water heater is HARD WIRED: (See Fig. 2.)

1. Obtain a piece of cable, the SAME TYPE (that is,
metallic or plastic) and SAME GAUGE with COPPER
conductors to make Item n connection (and Item l, if
needed) as shown. See also gauge selection chart
below.

2. Obtain 2 cable connectors (Item o) to fit the cable
above.

If your water heater is CORD and PLUG connected:
(See Fig. 3)

1. Obtain the SAME TYPE and GAUGE cordset with plug
as presently used on (Item l) and 2 strain relief
grommets (Item p) to fit THIS cordset.

D. TOOL YOU NEED:

1/4 wide Screw Driver, Hammer, Drill, Pliers, Wire
Cutter and Stripper.

SIZE OF FUSE OR MINIMUM GAUGE 125 OR WATER HEATER CAPACITY
CIRCUIT BREAKER OF COPPER WIRE 250 V 125 VOLT 250 VOLT

AMP. AWG. AMP. WATTS WATTS

15 14 15 1875 3750
20 12 20 2500 5000
30 10 30 3750 7500
40 8 40 5000 10000

STEP 2
Disconnect electricity to water heater. Pull plug,

if cord connected; remove fuse or open circuit breaker
if hard wired. CAUTION: - You may have to
remove TWO fuses or switch TWO circuit breakers to the
OFF position. If you are not sure which circuit(s)
are for the water heater; use a tester or consult an
electrician.

STEP 3

Spring
Holder

To Remove,
Tilt Top
Forward
And Lift Up.

Time
Switch
Mechanism

Plastic
Insulator

Remove time switch
mechanism from case
by depressing the
spring holder at top
left above the time
switch mechanism, tilt
the mechanism for­ward, and lift up and
out to remove from
case.

STEP 4

Mount time switch
case on wall as out­lined in STEP 1B.

Mounting
Holes

Mark mounting posi­tion, drill holes into
mounting surface
and drive screws into
holes. Use anchors, if
necessary.

Knockouts

STEP 5

If your water heater is HARD WIRED:
Remove the cover of water heater terminal box (Fig. 1, Item
m) IS ELECTRICITY TURNED OFF?
NOTE COLORS OF WIRES. Disconnect wires and
cable connector. Remove the most convenient knockout of
the time switch case and attach cable (Fig. 2, Item l) and
cable connector to case. Prepare another cable (Fig. 2,
Itemn) by stripping the ends of wires about half inch. Using
cable connector (Fig. 2, Item o), attach this cable to water
heater terminal box and then the wires to water heater
terminals.
NOTE: If you had green and / or white wires in the

terminal box before, you must connect the same
colors to these same terminals. TIGHTEN TERMINAL
SCREWS FIRMLY. Remove another knockout of the time

switch case and connect the other end of this cable to the
case, using the other cable connector, Item o.

158--01075

2

3

4

If your water heater is CORD and PLUG connected:

Remove plug at end of water heater cord (Fig. 1, Item l).
Split cord about 6 inches and strip wire ends 1/2 inch.
Remove the most convenient knockout of the time switch
case. Install strain relief grommet (Fig. 3, Item p) and
attach cord to case as shown. Next, install strain relief
grommet to the other cordset (Fig. 3, Item n) and attach
cordset to case as shown.

HARD WIRED

Cable
Connectors

CORD AND PLUG CONNECTED

Strain
Relief
Grommet

STEP 6

Spring Holder

Now, replace time switch mecha­nism in case. Slide in from above
so plate goes between “ears” on
either side of case. When in posi­tion, press top of plate until spring
holder snaps in place over plate.
Remove screw at the center of front
insulator cover and move insulator
out of the way.

Ears
Stops

STEP 7

Connect the wires coming from the service box and from the
water heater to the terminals of the time switch mechanism.

For specific wiring connections regarding your model,
refer to diagram inside the time switch door. Attach wire

ends to time switch terminals as shown in wiring diagram.
Insert only the stripped copper ends of wires UNDER the
pressure plates of terminal screws as shown. Use 3/16 or
larger screwdriver, tighten screws FIRMLY. (25 to 35 lb.
inches). CAUTION: Failure may occur if screws are loose.
Now replace front insulator cover and secure it with screw
furnished.

5

Pressure Plate

Terminal Screw
Make sure wire

insulation clears
pressure plate.

Grounding
Wire If Required

From
Service Box

To
Water
Heater

1/2”

STEP 8

Using pliers, grip folded down hasp on side of case and
rotate it upward as shown. Also, if your Time Switch has
an EXTERNAL MANUAL LEVER, pivot Override Lever
in direction shown until detents snap into position. Close
cover to make sure the holes in cover line up. Adjust, if
required.

Adjust
If Required

ELECTRIC
WATER HEATER TIMER

by

Guide Detents

Manual
Lever

Hasp

Operating
Lever

STEP 9

Set your daily program. - See operating instructions on page

7. Each individual household should determine a schedule
to suit their own needs. Adjustments should be made for
family size, hot water needs, appliances, etc. In areas
where time-of-day rates are in effect, consult your electric
utility company to find when the lowest rates apply. Then
set your time switch to operate your water heater when
your electric rates are lowest and adjust your schedule
accordingly.
In setting your schedule, you must consider the facts that
the temperature and quantity of hot water will decline during
the “OFF” periods depending on amount used and length
of “OFF” time. A typical schedule could be “ON” at 6 AM,
“OFF” at 8 AM for your morning use, and “ON” AGAIN AT 5
PM AND “OFF” again at 10 PM.

6

DAYS AM HOURS PM HOURS
OF WEEK 2 4 6 8 10 1 2 2 4 6 8 10
MONDAY

TUESDAY

WEDNESDAY

THURSDAY

FRIDAY

SATURDAY

SUNDAY

Indicates when water heater is on.

OFF

TRIPPER

ON

TRIPPER

OFF

TRIPPER

VIEW OF DIAL AT MIDNIGHT

TYPICAL PROGRAM

ON

TRIPPER

ON TRIPPER

OFF TRIPPER

STEP 10

Check wiring, time setting (AM/PM) and program. If hard
wired, also close Water Heater Terminal Box. Restore
electric service (the reverse of STEP 2). By looking
through the oval motor check hole, you should be able to
observe time switch clock motor gears in motion. Close
time switch cover. Make sure it is latched and locked, if
needed.

OPERATING INSTRUCTIONS

This Time Switch will repeat a preset schedule daily. It may
also have an EXTERNAL MANUAL LEVER to override
the automatic program. The diagram on the right shows the
mechanism and typical wiring.
THE CLOCK DIAL - Turns in a clockwise direction once a
day and has a 24-hour face.
THE TIME POINTER - is used to line up the correct time-of­day on the dial.
THE TRIPPERS - are attached to the dial, turn the water
heater ON and OFF at times indicated by their respective
position on the dial
THE MANUAL LEVER - permits the user to turn the water
heater ON and OFF ahead of schedule. The Time Switch
will resume the preset program by the next scheduled ON or
OFF operation.

7

NOTE: The manual lever is inoperative for 15 minutes
immediately after the automatic operation.

TO SET PROGRAM - First mount green finished “ON” trip­pers at times you wish electric water heater to start operating.
Place gold “OFF” trippers at times you want to turn water heat­er off. Fasten trippers securely by turning screws tight against
clock dial. Second, pull clock dial toward you and turn clock
dial in in either direction to the correct time-of-day as indi­cated by pointer. DO NOT MOVE POINTER. Close the time
switch cover. Make sure it is latched and locked, if needed.
AFTER POWER FAILURE (or if your water heater was
disconnected at the main panel) - you must reset the
clock dial to the correct time-of-day.
TO SUSPEND AUTOMATIC OPERATION - remove trippers
from dial. Set manual lever as desired.

CAUTION: Always disconnect power at main panel
before servicing this switch or the water heater.

CLOCK
DIAL

ON TRIPPER

TIME
POINTER

GROUND
SCREW

120/240V
60 HZ
FROM
SERVICE
BOX

GRD

NEUT

LINE 1

LINE 2

INTERMATIC INCORPORATED

SPRING GROVE, ILLINOIS 60081-9698

NEUTRAL (WHITE) IF PRESENT

GROUND (GREEN) OR BARE

8

MOTOR
CHECK
HOLE

OFF TRIPPER

MANUAL
LEVER

TO
WATER
HEATER