Off-peak option 4:
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 |
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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. |
 Larger 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-simultaneous
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.
Resource:
Read about 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.
Resource:
Read about two water heaters
Add timer to either water heater or both 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
Resource:
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. |
Resource:
Larger image
How thermostats work
How to wire thermostats |
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If water heater has foam
insulation, then replacing lower thermostat with ECO protected
thermostat may not be easy.
Take
apart most upper thermostats 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:
|
 |
 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 GM series timer
Buy:
GM40AV
120-208-240-277V
GM40AVQ w/
back-up battery
Resources
How to wire GM40 series timers
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
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
Buy
240 volt/ 7-day:
Intermatic
EH40 timer
30
amp water heater timers
Resources:
Water heater timers
EH40 water heater timer
Things you can do to increase amount of hot
water
9 ways to save with water heater
|
> Upper thermostat operates
normally to keep top 2/3 tank hot.
