How to wire water heater thermostat

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How to wire water heater thermostats

Non-simultaneous Dual element,
Single element 240Volt
Single element 120Volt
Off-peak thermostats
Redundant thermostats
Two water heater
Simultaneous

NON-simultaneous water heater thermostats

Ordinary Dual-element 240 Volt residential water heater is non-simultaneous

ECO-protected upper thermostat

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Bradford White tank

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Ordinary water heater

Both elements are never 'on' at same time unless tank is wired for other purpose (see owners manual). This is called 'non-simultaneous operation' since both elements are not 'on' at same time.

Either upper element is 'on' or lower element is 'on,' or both are off.

Upper thermostat is main controller <> it turns on upper element until top 2/3 of tank reaches temperature, and then sends power to lower thermostat. Lower thermostat heats bottom 1/3 of tank, and turns on and off to maintain tank temperature during standby hours when no hot water is being used.

Sequence showing non-simultaneous operation
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NON-simultaneous: Household electric water heaters are wired for NON-simultaneous operation. Both elements are not ON at same time. Upper element is ON, or Lower element is ON, or both elements are OFF. How electric water heater works

Dual-element upper thermostat used on 240V water heaters that have 2 elements	Single element 120 Volt or 240 Volt residential water heater Some water heaters have 1 heating element >> Same thermostat used for both 120V or 240V > For correct voltage of water heater, look at label on side of tank
Dual element upper thermostat Screw numbers include L1, L3, L4, T2, and T4 Screw numbers can also be 1, 3, 2, and 4 See Larger	Single element thermostat Screw numbers are 1 thru 4 See Larger	240 Volt single thermostat See Larger 240 Volt single	120 Volt single thermostat See Larger 120 Volt single
		Dual element thermostats See larger

Off -peak water heater thermostats
See more OFF-peak options Off peak with two water heaters Off peak 120Volt
	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 when ordered by off-peak meter or timer Compare: Off-peak water heater thermostats Ordinary 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 150-180°F 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 yellow wire and each black wire at top of water heater See Off-peak operation sequence	Ordinary tank wiring
Off-peak water heater timer	How to wire off-peak water heater to timer Lower thermostat receives power only when timer orders > Upper thermostat receives power full time	Homeowners should check with plumber before altering water heater wiring.
Sequence showing off-peak operation
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OFF-Peak Non-simultaneous 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.

Redundant thermostats

Only lower element operates

Step 1:
Remove blue and yellow wires from upper thermostat
Step2:
Move black wire from terminal T4 to terminal T2
Tighten screws very tight against copper wire.
Step3:
ECO protected thermostat must remain at top of tank to protect against overheating event.

Redundant thermostat

Upper element is disconnected.
Lower element heats tank.
Water heater responds immediately when cold water enters tank.
Can possibly cause more stacking events

Both thermostats control lower element.

When upper part of tank cools, the lower element turns ON. Hot water rises.
When lower part of tank cools, lower element turns ON.
ECO-protected thermostat must be kept at upper part of tank to avoid overheating event that can damage or rupture tank, cause scalding, release of hot water through TP valve and distill chemicals out of the water.

Cold enters lower part of tank through plastic dip tube.

Homeowners should check with plumber before altering water heater wiring. See insurance data on water heater failure

Redundant thermostats control 2 water heaters
	Additional tank in series to double available hot water at peak times See wiring option below Read about two water heaters
Larger image	Redundant thermostats control 2 water heaters 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 hot 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 might be 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
Non-simultaneous thermostats control two water heaters
Larger image	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 basically 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
	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:
	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 turn on-off at same time More box-type water heater timers

Simultaneous water heater thermostats
	Simultaneous water heater wiring Used in large water heaters when elements cannot keep up with demand, or in high demand situations. Lower thermostat replaced with ECO protected thermostat. Each thermostat is wired separately. Each thermostat wired to a separate circuit breaker, since each element draws 4500 to 5500 watts.
	Simultaneous water heater wiring Upper and lower thermostats and elements work independently from each other. Increased first hour delivery of hot water Faster recovery time 4500Watt elements, then total wattage is 9000 watts. Use 50 amp breaker and #6 gauge wire or two 30 amp breakers and two 10 gauge wires 5500Watt elements, then total wattage is 11,000 watts Use 60 amp breaker and 6 gauge wire or two 30 amp breakers and two 10 gauge wires Oversizing breaker and wire runs cooler and is more efficient Off-peak Connect lower thermostat to timer and convert water heater into off-peak operation. Water heater companies are integrating their products with future smart-grid. Except they are installing electronic thermostats. Consider whole house surge protection Whirlpool's (American/ AO Smith water heater) new 'energy smart' The era of generic off-the-shelf parts is coming to an end quickly as companies try to boost sales by using proprietary parts that must be ordered from them. SO buy extra parts and water heaters now.

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NON-simultaneous water heater thermostats

Ordinary Dual-element 240 Volt residential water heater is non-simultaneous

Single element 120 Volt or 240 Volt residential water heater

Off -peak water heater thermostats