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2014

How to wire off-peak water heater

Homeowner should check with plumber/electrician before altering water heater wiring
Altering wiring will void product warranty. Tip: Don't call water heater manufacturer and report that your installation is out of warranty.
AO Smith wiring diagrams
See all electric water heater thermostat wiring diagrams
Off-peak option 1: Rewire thermostats for peak operation
Off-peak thermostat wiring

240 Volt potential exists between L3 yellow wire and each L1 black wire
Large image of EH40 wired for off-peak

1) Off peak thermostat wiring / one 30 amp breaker

EH40 timer wired for Off-peak

Purpose of off-peak ... save energy during peak electric prices.  
> Upper thermostat operates normally to keep top 2/3 tank hot.
> Lower thermostat heats bottom 1/3 of tank only when ordered by off-peak meter or timer

5 steps for wiring Off-peak water heater thermostats

1. Lower thermostat replaced with ECO-protected thermostat identical to upper thermostat. ECO safety red reset cuts off power when water in tank reaches dangerously high 150-180F

2. Upper thermostat: Red wire is moved L4 to T4. Color of wires can be different.

3. Black wire from lower thermostat does not connect to upper thermostat T4 screw

4. Black wire from lower thermostat runs to top of water heater for connection to off-peak meter, or off-peak timer

5. 240 Volt potential exists between L3 yellow wire and each L1 black wire at top of water heater
water heater thermostats
Compare with peak wiring
Larger
Buy:
EH40 at Amazon

Resources
EH40 water heater timer
How to wire water heater thermostats
How to adjust temperature on gas and electric heaters
Water heater temperature for killing bacteria 140F - options advisories
Ways to increase amount of hot water
Off peak water heater sequence
Larger image

OFF-Peak operation.

Lower element turned OFF during off-peak.
Upper element keeps top of tank hot
Less hot water is available.
When off-peak ends, normal NON-simultaneous operation resumes.

Resource:
How water heater works
CA3750 off-peak water heater
Larger image

2)  3-for-1 options     Z wave control / two 30 amp breakers

a) Off-peak water heater 

b) simultaneous water heater

c) change water temperatures

Set different scenes to utilize all 3 choices

Select 240Volt operation
Choose 2xSPST

Control upper and lower parts of tank separately:
Required; ECO-protected thermostat installed in place of lower thermostat

1): Off peak
    Upper thermostat receives power full time
    Top part of tank heats normally
    Turn off power to lower part of tank during peak electric prices
    Less hot water is available during peak, but water is fully heated

2) Simultaneous: this wiring is for simultaneous operation... when both thermostats are ON, water heater recovers faster. More hot is available.

3)  Change water heater temperature using 2xSPST.
   Lower thermostat receives power full time
   Set Lower thermostat to regular temperature/ 120F
   Lower element and thermostat heat tank each day
   Set Upper thermostat to higher temperature 140F
   Wash day, upper thermostat receives power
   Top part of tank has very hot water available for washing clothes
Buy:
Intermatic CA3750 at Amazon
Intermatic CA3750 at Amazon
Resources
How to set-up and wire CA3750 z-wave contactor

Off-peak option 2/ timer

1) Add a timer

Turn water heater off during peak price

Compare water heater timers
Gas water heater timers
Box timers and wiring
Countdown timers
Programmable wall timers
How to connect programmable and countdown wall timers
Box timers and wiring
Intermatic CA3750
Larger image

2) Control electric water heater with Z-wave

Intermatic CA3750 contactor module
Intermatic CA3750 at Amazon
Z-wave water heater

Control gas and electric water heater with Z-wave

Control electric water heater with z-wave

Control gas water heater with remote control

Insteon 2477SA1 X10 load controller

Control gas and electric water heater with X10

Control electric water heater with X10

Control gas water heater with X10
Elk remote control contactor Elk X10 remote control contactor (relay)

Plug into 120V outlet.
Relay works with automated hardware.
Rated up to 60 amps.
Buy:
Elk relay contactor at Amazon

Resource:
Elk-9200 manual
Box timers and wiring
Aube CT241 phone controller

3) Aube CT241 telephone control

Control appliances/ water heater over the phone.
Uses old fashioned plug-in phone cord
Aube CT241/ 24V ac output / requires contactor
Plug provided transformer into 120V outlet
Universal relay outputs are dry. Up to 10 amp load
Connect relay to contactor
Manual
Buy
CT241 at Amazon
Resources:
CT241 manual
Use Aube controller to operate contactor. Contactors
Computer controlled relay

4) Computer controlled relays

USB or Zigbee Wireless
Requires quick start kit and/or adapters in addition to device

Example manual

Off-peak option 3: Add another water heater to store hot water

...so more hot water available at usage time
Add timer to either water heater -or- both water heaters
Two water heaters Install tanks in series:
Cold water enters heater #1 and then feeds into heater #2.

Wiring goes in reverse order:
Wire from circuit breaker arrives at heater #2, and then goes to heater #1 (as shown diagrams below)

IF WATER HEATER HAS FOAM INSULATION the wiring may not be possible without drilling hole to drop additional wire into lower part of tank.
This action will void water heater warranty.
Remember, for water heater to work correctly, the thermostats and element must be covered with insulation or thermostat will misread temperature.
Reduntant thermostats - two water heatersLarger image
Add timer to either water heater or both water heaters

Redundant thermostats control 2 water heaters
Set upper thermostats at lower temperature than lower thermostats

Purpose:
Add additional tank so more hot water available at peak times, without adding additional wiring from breaker.

Heater #1 must be satisfied before power is sent to heater #2.
Heater #2 may not fully heat before heater #1 needs to turn ON again. This will happen IF water heater is poorly insulated or cold water is drawn from heater #1 or incoming water is very cold.

Sequence:
1) Power  from circuit breaker arrives at ECO-protected upper thermostat on heater #1
2) ECO protection required on upper part of tank to prevent overheating event since heat rises
3) Typical lower thermostat on heater #1 is replaced with ECO thermostat so power can be transferred to heater #2 when heater #1 thermostats are satisfied.
4) Once heater #1 is satisfied, power goes to heater #2.

Either heater can be wired for redundant or typical non-simulataeous operation.
The key is adding ECO-protected thermostat to lower part of heater #1, and adding wire from lower thermostat so power can be transferred to heater #2.

Water heaters with foam insulation may require long drill bit from home center or fry's to bring wire to top of tank. Be sure insulation and covers are put over thermostats so thermostat not exposed to cool temperatures and cause temperature misread.

Read about two water heaters
Two water heaters Non-simultaneous thermostats control 2 water heaters
Simultaneous wiring will heat top of tank first.
Redundant will turn ON as soon as cold water enters tank. How electric water heater works

Purpose:
Add additional tank so more hot water available at peak times, without adding additional wiring.

Heater #1 must be satisfied before power is sent to heater #2.
Heater #2 may not fully heat before heater #1 needs to turn ON again. This will happen IF water heater is poorly insulated or cold water is drawn from heater #1 or incoming water is very cold.

Sequence is generally same as above.

Water heaters with foam insulation may require long drill bit from home center or fry's to bring wire to top of tank. Be sure insulation and covers are put over thermostats so thermostat not exposed to cool temperatures and cause temperature misread.

Read about two water heaters
Why does this work?
240volt water heaters have two hot wires from breaker. Each element is permanently connected to one hot wire, and will always test hot for 120Volt to ground.
Thermostat opens and closes second hot wire to element. This action turns element ON-OFF
Basic water heater circuit
Thermostat is either Hot on T2 or Hot on T4, but never both.
Some ECO thermostats are numbered 2 and 4.
So the lower thermostat on water heater #1 will either send power to lower element on heater #1, or it will send power to heater #2.
Water heater #2 will not turn ON unless water heater #1 is OFF
When water heater #1 turns OFF, then heater #2 has 240V power available.

Larger image
How thermostats work
How to wire thermostats
Take apart thermostats If water heater has foam insulation, then replacing lower thermostat with ECO protected thermostat may not be easy.
Take apart upper thermostat and make new lower thermostat that will work for the specific two-water heater diagrams shown above.

When not to use:
Do not remove ECO protection on upper part of tank.
On simultaneous and single-tank off-peak water heaters, the ECO is require for lower thermostat operation.
ECO protects you in case of overheating and is required for safe operation of water heaters.
If you cannot rewire water heater:
WHQ4 Water heater timer  WHQ water heater timer If you cannot rewire water heater because of foam insulation or other factor such as warranty:

Re-plumb water heaters in series, and run additional 30 amp circuit to additional heater. Then put both water heater on a timer
See basic water heater circuit

Water heater timer for two water heaters
Both water heaters have same schedule & turn on-off at same time

More box-type water heater timers
Control 2 water heaters Control 2 water heaters

Each water heater can have different 7-day schedule

10 gauge wire and 30 amp breaker run cooler.
30 amp circuit breaker and 10 gauge wire for water heater runs cooler with less energy loss. Breaker box lasts longer.

Different wiring:
For two 4500 watt water heaters, you can use one 40 amp breaker and 8 gauge wire to bring power from breaker box to the first timer.

For two 5500 watt water heaters, you can use 50 amp breaker and 8 gauge wire
Water heater timers
EH40 water heater timer
Things you can do to increase amount of hot water

9 ways to save with water heater

Off-peak option 4: Re-wire circuit from 240Volts to 120Volts

... for homes with very low consulption

How to wire water heater for 120 Volts Re-wire water heater circuit from 240Volt to 120Volt.
Not correct option in homes with several people.

Wires inside water heater are NOT changed.
Reduce electric consumption by heating water more slowly.
Water heater will not 'recover' as quickly. Instead of heating 20 gallons hot water per hour, tank will heat about 5-10 gallons per hour.
Physics has not changed: it still takes same Kwh to heat gallon of water. This option is for low-consumption homes, in areas that have peak electric pricing.

Inside breaker box:
Move black wire from 240V breaker to 120Volt circuit breaker rated for correct amps.

Move white wire from 240V breaker to Neutral busbar where ground wire connects.
Some breaker boxes have separate Neutral busbar where white wires are connected.

Read more about this option

Gas and electric water heaters Support the economy:
Buy water heaters  from my associate links:

50 gallon Gas water heaters at Amazon
40 gallon gas water heaters at Amazon
50 gallon Electric water heaters at Amazon
40 gallon electric water heaters at Amazon
Hybrid / heat pump/ water heaters at Amazon

Resources:
How to install gas water heater
Troubleshoot gas water heater
Troubleshoot electric water heater
box timers Compare box timers

Control water heater w/ Z-wave
Intermatic control centers Intermatic control centers:
+ manuals and parts

Freeze control centers

Basic timer control centers

Digital & Z-wave centers
programmable timer Compare programmable timers

Control water heater with programmable wall timer
Countdown timers Compare countdown timers

Control water heater with countdown timer
Low voltage power packs Low voltage transformers
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