Guide to the aquastat reset button:

Where is the reset button on a heating boiler or water heater aquastat control? How to use the reset button: press it once? Why not twice? What to do if the red plastic reset button itself has been broken off or lost.

Where are all of the reset buttons & switches found on heating boilers & water heaters?

This article series explains how aquastats work and what the different aquastat controls are, what they do, and how they are set. We define various controls on heating boiler aquastats and explain what they do and how they work. We explain the location and use of the heating boiler reset button found on aquastats.

How to Find and Use the Reset Button on the Aquastat Combination Control on a Boiler

Summary of the Functions of a Typical Combination Protectorelay™ Primary Control and Aquastat® Controller

[Click to enlarge any image]

Our photo shows an older aquastat type primary controller on an oil fired heating boiler. You can see the gray box covering the control in the right in our photo and near the top center of that control cover you can see the aquastat's red reset button.

The coiled "wire" leaving the upper right corner of this control is routed to a thermal sensor mounted in a well inserted into the water of the heating boiler.

Unlike the aquastat shown at the top of this page, poking through the upper-center of the cover of this heating system control you'll see a red " reset button " in the center of the upper portion of the gray control box.

If this heating boiler or water heater has turned itself off - SAFETY OFF -  you'll see that the red reset button will have popped UP higher out of the control cover.

If the red "reset" button on the this safety control is sticking up and the oil burner has shut down, the homeowner is permitted to try ONCE ONLY to "reset" the system by pressing the red reset button. Also see our more detailed instructions for using the reset button on heating equipment at our

article: CAD CELL RELAY SWITCH.

Just below I've removed the cover so that you can see the actual reset switch (green arrow).

Depending on wiring hookup choices, this control operates the heating system oil burner, circulator, and zone circulators. An aquastat can also be configured (factory default) to keep the heating boiler hot to provide domestic hot water through a tankless coil even when the building room thermostats are not calling for heat.

The aquastat controller often also includes connections to a flame sensing device, typically a cad-cell

See details at CAD CELL RELAY SWITCH

or on older heating systems a stack relay to shut down the boiler if the burner is not operating properly.

See details at STACK RELAY SWITCH

Above: I'm pressing the reset button on the actual reset switch inside the aquastat of a heating boiler.

Watch out: there is live electrical voltage inside of heating and water heater controls. Removing the cover risks fire, shock, or death from electrical shock if you touch live wires or live electrical connections or screw terminals.

There is a "reset" button to re-start the heating system if it has shut down for safety. We discuss all of these controls in detail below.

See RESET SWITCH on PRIMARY CONTROL

Watch out: sometimes the red plastic button on older heating equipment primary controls can break off.

At RESET SWITCH, HEATER REPAIR we show how to reset the equipment safely if this happens to you.

Question: We have to hit the reset button on our furnace for it to run.

(Nov 23, 2015) Jackie said:
We have to hit the reset button on our furnace for it to run. It runs for 4-5 heating/hot water cycles,then reset button again. We took the cover off the Aquastat(L8124A) and saw a semi exposed wire and the circuit board looks like it been arced.

Not sure if arcing mark is from close proximity to exposed wire or damage to board. Should I replace connector(to correct exposed wire) or aquastat or control box?

(6 March 2016) Kev said:

My overheat button knocks off boiler its a honeywall.is there a suggestion what might cause this

Reply: do NOT keep pressing the heater or water heater reset button

Jackie:

Watch out: repeated use of the re-set button risks a dangerous puffback explosion. That's because the burner that is shutting off on "safety" may leave un-burned fuel in the combustion chamber; it can accumulate until we have an ugly experience.

If you see arcing burns on the circuit board I suspect the problem may be more than the wire - perhaps overheating. I would ask for an inspection by your heating service tech to decide:

1. what's causing the system to go off on re-set

2. what caused the arcing you found

3. based on those steps, repair or replace what's needed.

I understand the appeal of just plugging in a new part - certainly I do that myself. But just swapping in a new control or circuit board without having an idea of what was happening risks having to repeat the repair.

See OIL BURNER SOOT & PUFFBACKS

Kev:

If you are referring to the reset button on an oil fired heating system most likely the problem is with the oil burner: an inadequate or faltering flame. DO NOT keep pressing the reset button as you could cause a dangerous puffback explosion. I'd call for service.

Question: blinking green light on boiler controller

2016/10/27 DD. said:

My heater green light blinks. I tried to set but it back on blinking. What might be reason please?

Reply:

DD

I can only guess since you haven't said what type of heating system you've got installed nor given me the brand and model ofd the heating system controller. Here's an example that might help:

IF your system is using a Honeywell R7184 aquastat controller, and IF someone pressed the RESET button two times without a successful call for heat, THEN the indicator light will flash at one-second intervals, or as the control manual says at 1HZ 1/2 second off, 1/2 second on.

You can RESET the controller by pressing and holding the RESET BUTTON for at least 30 seconds. That should stop the green blinking.

Watch out: if still your heating system will not start and run normally, do not keep pressing the reset button as you could cause an unsafe condition. Instead, call your heating service company for repair assistance.

If the Honeywell R7184 is what's found on your heating boiler and if you do not already have the instruction manuals fodr this control you can download them from honeywell.com OR free from

• HONEYWELL R7184 Interrupted Electronic Oil Primary R7184A,B,P,U Installation Instructions, also available at www.honeywell.com
• HONEYWELL R7184 Series Primary Controls Technicians Quick Reference Guide, also available at www.honeywell.com

Where are all of the Air Conditioner, Cooling, Heating, Heat Pump & Water Heater Reset Buttons Located ?

Above: red reset button on the cad cell relay found on many oil burners used on boilers, furnaces, and water heaters.

If you are looking for the main reset button on heating equipment you'll want to see

COOLING & HEATING CONTROL & SWITCH INDEX - master index to all controls for cooling or heating equipment reset buttons, switches, controls, or see the suggested articles below:

• A/C - HEAT PUMP CONTROLS & SWITCHES - identifies all of the controls and switches that control or may turn on or off air conditioners and heat pumps. Some of these switches can be tricky to find and use properly. For example a condensate tray overflow switch or a blower compartment door safety switch can leave your air conditioner or furnace off when nothing else is wrong.
• AQUASTAT RESET BUTTON - reset button found on aquastats used on heating equipment such as boilers & water heaters.
• CAD CELL RELAY SWITCH - hot water boilers and some water heaters that are oil-fired use this switch as a safety control. It turns off the oil burner if the flame is not solid
• DISTRIBUTION PANELS - where to find the circuit breaker controlling the equipment that is OFF - check for a tripped circuit breaker or blown fuse. Sometimes you may need to trace an electrical circuit to find which breaker or fuse is powering which device.
  
  See ELECTRICAL CIRCUIT ID, MAP & LABEL
• ELECTRIC MOTOR OVERLOAD RESET SWITCH - some electric motors such as at oil burners and well pumps include a user re-settable thermal overload switch or reset switch. Other motors contain an internal thermal overload switch that will reset itself when the motor cools down.
• ELECTRIC PANEL INSPECTION - things to look for when examining an electrical panel to find circuit breakers controlling heating equipment
• ELECTRICAL POWER SWITCH FOR HEAT - lists the various ON / OFF switches found on cooling & heating equipment. Note that ON/OFF switches for cooling or heating may also be found on some thermostats.
• ELECTRIC WATER HEATER THERMOSTATS - include thermal reset or overload switches
• FIRE SAFETY CONTROLS - used on oil fired heating equipment
• FIREMATIC FUSIBLE ELECTRICAL SWITCH - interrupts electrical power in event of fire near heating equipment
• LOW WATER CUTOFF CONTROLS - on steam heating systems.
• RESET SWITCH, HEATER REPAIR - what to do if the red plastic reset button has been broken off or lost
• MANUALS for HEATING & A/C SYSTEM CONTROLS
• SINGLE FUNCTION LIMIT SWITCH - a high or low temperature control found on some heating boilers and water heaters
• STACK RELAY SWITCH - on older oil fired boilers and furnaces you may find this safety control on the flue-vent connector or "stack pipe"
• FLUE GAS SPILL SWITCH TRIPPING & RESET - gas fired equipment
• THERMOSTATS, HEATING / COOLING - if not working or not set properly, will leave heat stuck off, on, or cycling improperly

...

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-04-16 - by (mod) - Honeywell Aquastat L4046H HI-LIMIT controller reset button troubleshooting

Thanks, do keep me posted - it'll help other readers.

Be double sure you've ruled out the obvious like a bad wire or connection and that you're not trying to reset while the heater is still hotter than the limit setting.

On 2020-04-16 1 by Jacob

Thank You for your help I’ll keep you posted when I get a new controller. The system has been cold since yesterday. I really appreciate your help

On 2020-04-16 1 - by (mod) - L4046H HI-LIMIT controller reset button doesn’t move when I push it.

Thanks for the added photos, Jacob - that's an L4046H HI-LIMIT controller, not the L7224U - (I guessed wrong).

If the reset button on an aquastat or limit control will not re-set there are some steps to follow - don't assume that the control is defective.

For the Honeywell L4006H reset button refusing to re-set:

1. Let the system cool down so that we can be sure that the High Limit control is not keeping the burner off because the temperature in the water heater or boiler is too high: exceeding the upper limit set on the control.

2. Check power supplied to the control to confirm that it's getting voltage.

3. When the system is cool, if the reset button won't reset the control then the control is defective and needs replacement.

The manual for your control can be downloaded or read as a PDF at this link:

HONEYWELL L4006A,B,E, H HIGH LIMIT CONTROL MANUAL [PDF]

Here is what that manual says about the reset button:

When the device includes manual reset (L4006E and H), be sure to press the red reset button on the front of the case to make sure that the controller is not locked out on safety.

When checking out the system, adjust the control point low enough so the temperature of the controlled medium reaches the high limit setting, the burner shuts off, and the Aquastat Controller locks out.

When the temperature of the controlled medium drops to the high limit setting minus differential, push the manual reset button and the system should be operative again.

Reset control to proper high limit setting.

On 2020-04-16 by Anonymous - Honeywell Aquastat L4046H HI-LIMIT controller

This reset button [on the Honeywell L4046H shown in 2 photos above] doesn’t move when I push it.

On 2020-04-16 by Anonymous

Honeywell Type L4006H. This is the Manual Reset Aquastat.

On 2020-04-16 - by (mod) - Honeywell L7224U (Universal Aquastat) then an Err5 Code

Jacob,

I need to know your aquastat brand and model.

**IF** yours is a Honeywell L7224U (Universal Aquastat) then an Err5 code is described at AQUASTAT L7224U UNIVERSAL OPERATION & ERROR CODES

• ERR 5 = Low line voltage, check L1/L2 110VAC,

I don't assume that the Aquastat itself is defective.

Watch out: if you are not familiar with safe electrical wiring and testing, fooling with or touching contacts or wires inside the control can cause shock or electrocution, (death). Instead get help from a trained service tech.

That warning given, I might turn power off to the control, then disconnect the L1 L2 wires, then with power on, check the voltage being delivered to the control.

If that voltage is normal (around 120 VAC) then I'd reconnect the power to the control, remove its other wires (label them so they can be re-connected properly), and check those wires for a short between wires and/or a short to ground, then reconnect them sequentially while watching the control for the error message.

See details at HONEYWEL

On 2020-04-16 by Jacob - aquastat thermostat reset button won’t reset my system.

My aquastat thermostat reset button won’t reset my system. I keep getting Err 5 on aquastat relay. My question is? Is the thermostat no good

On 2017-10-17 - by (mod) - Peerless boiler reads ERR - 10

Marge,

If you tell me the aquastat brand and model we can help dig up the installation/operation manual that will have the error codes explained.

**IF** your aquastat is the one we discuss

at HONEYWELL L7224U AQUASTAT DIAGNOSIS

THEN ERR 10 - discussed on that page - means

Warning: Boost Failure; Boost Mode active at least once per cycle for the last 60 consecutive cycles.

Check Outdoor Reset curve settings.

On 2017-10-17 by Marge

The electronic aquastat on my daughter's Peerless boiler reads ERR - 10. What does that mean?

Also, when I tried resetting the aquastat, which I did a couple of times with about 5 minutes in between there was a puff of smoke from the boiler itself. The boiler was just cleaned last Friday and on Monday there was not hot water.

On 2017-03-19 - by (mod) -

Check the aquastat settings - be sure that the HI is at least 20 degF above the LO

On 2017-03-19 by Brian C

Burner fires for call of domestic hot water but not for baseboard heat. Both zones no heat.

...

Continue reading at RESET SWITCH, HEATER REPAIR we show how to reset the equipment safely if the plastic button has been broken or lost, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• AQUASTAT CONTROLS - home
• AQUASTAT HI LO DIFF SETTINGS
• AQUASTAT LO & DIFF DISABLED
• AQUASTAT L4006, L4006E, L4007 HONEYWELL GUIDE [PDF]
• AQUASTAT L4080B,D & L8080A HONEYWELL MANUAL [PDF]
• AQUASTAT L4080B,D,F,G & L8080A HONEYWELL MANUAL [PDF]
• AQUASTAT L6006A HONEYWELL GUIDE
• AQUASTAT L7224U UNIVERSAL OPERATION & ERROR CODES
• AQUASTAT L7224U UNIVERSAL DIAGNOSIS
• AQUASTAT L8124 AQUASTAT INSTALL / REPAIR
• AQUASTAT L8148 AQUASTAT INSTALLATION
• AQUASTAT L8148 HONEYWELL DIAGNOSIS & REPAIR
• AQUASTAT L7224U UNIVERSAL OPERATION & ERROR CODES
• AQUASTAT L7224U UNIVERSAL DIAGNOSIS
• AQUASTAT L8124 AQUASTAT INSTALL / REPAIR
• AQUASTAT L8148 AQUASTAT INSTALLATION
• AQUASTAT L8148 HONEYWELL DIAGNOSIS & REPAIR
• AQUASTAT R8182-SERIES CONTROL
• AQUASTAT RESET BUTTON
• AQUASTAT SENSOR PROBE HEAT CONDUCTING COMPOUND
• AQUASTAT SENSOR PROBE STUCK in the AQUASTAT WELL
• AQUASTAT SETTINGS vs HEATING COST
• AQUASTAT SELECTION GUIDE
• MANUALS for HEATING & A/C SYSTEM CONTROLS for a list of aquastat installation & repair guides
• RESET SWITCH, HEATER REPAIR

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AQUASTAT RESET BUTTON at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

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