Thermostat Reading Off and Wont Turn Heat Won't

Heat Won't Turn OFF: troubleshoot the thermostat
iv Steps to accept if the heating arrangement won't plough off

• Mail a QUESTION or Annotate about heating, air conditioning, and heat pump thermostat installation and wiring

InspectAPedia tolerates no conflicts of interest. We accept no relationship with advertisers, products, or services discussed at this website.

Diagnose & fix heat that won't turn off when it should: here nosotros discuss diverse causes of too much heat or of a heating organisation that does not shut off whenit should.

We explain how to diagnose and ready thermostat switch settings, switch settings right at the air conditioner or furnace air handler, and we review thermostat wiring problems that cause a heating arrangement or cooling organisation to stay ON when it should not.

We provide a sequence of diagnostic steps that decide if the trouble is at the thermostat, the thermostat wiring, or at other heating or cooling system controls.

We also provide an Commodity Index for this topic, or you lot can try the page height or bottom SEARCH BOX as a quick mode to notice information you need.

Thermostat Troubleshooting: heating or cooling arrangement won't plough OFF

Here we talk over how to diagnose & fix a thermostat that keeps calling for heating or cooling when it should not.

A dissever article, HEAT WON'T TURN OFF, gives diagnostic procedures for other reasons why building oestrus wont' plow off too problems at the thermostat itself.

Article Contents

• THERMOSTAT WON'T Turn OFF - page top
• Pace 1: Modify THE THERMOSTAT SETTING
• Stride 2: CONFIRM Trouble in THERMOSTAT or WIRES
• Footstep 3: Bank check DAMAGED THERMOSTAT WIRES
• STEP 4: IF THE PROBLEM is NOT THE THERMOSTAT
• EXAMPLES of THERMOSTAT TROUBLESHOOTING
• HEAT WON'T Turn OFF - separate commodity to see if the trouble is definitely non the thermostat

First Stride: Alter the thermostat setting up or down

If the heating arrangement won't turn OFF, that is if estrus keeps being delivered even when y'all don't want it, set the thermostat to its lowest temperature setting and wait three to v minutes.

Or if your thermostat has a Heat OFF Absurd or FAN AUTO OFF control, set the control to OFF or COOL.

For help locating these thermostat switches run into THERMOSTAT SWITCHES, EXTERNAL.

• If the heating system stops then the problem is nigh likely the thermostat setting,

  See THERMOSTAT Calibration

  or THERMOSTAT WIRE CONNECTIONS, or external influences like position of the thermostat on the wall, exposure to drafts, etc. Yous might as well want to

  see TEMPERATURE RESPONSE of ROOM THERMOSTATS

• If the heating organization does not end continue to Stride 2 below.

Watch out: for warm air estrus blower units behave differently than hot water or steam heat systems: to avoid damage to the heat exchanger the air handler or blower unit will usually go along running for a minute or fifty-fifty a few minutes later the thermostat has stopped calling for heat. So for warm air heating systems, requite the arrangement a few minutes to close downwardly.

If the air handler, blower unit, or fan won't stop,

see FAN WONT Cease - THERMOSTAT SWITCH

For hot water and steam heating systems, because the heating baseboards, convectors, or radiators will exist hot and because they have some thermal mass, rut continues to be delivered for a longer interval even after the heating system itself has stopped.

Therefore to check whether or not setting the thermostat temperature down to its lowest setting (or to OFF) has turned OFF the heating arrangement y'all need to listen to the heating unit itself to discover that it has stopped.

If the cooling system wont' plow OFF, that is if cool air keeps being delivered even when you don't want information technology, nosotros practise the opposite: set the thermostat to its highest temperature, or if your thermostat has a Oestrus OFF COOL or FAN AUTO OFF control, set the control to OFF or Estrus.

• If the cooling system stops then the problem is most probable crusade of the problem was the thermostat setting,

  the THERMOSTAT CALIBRATION, (including placement on the wall)

  or THERMOSTAT WIRE CONNECTIONS,

  or external influences.

• If the cooling system does not stop continue to Footstep 2 beneath.

Unlike the heating systems described to a higher place, the commitment of cool air from an air conditioning system or a heat pump arrangement in cooling mode will normally stop within less than a infinitesimal of setting the thermostat to its highest setting or to OFF.

Step 2: confirm that the problem is in the thermostat or its wiring

Forced Warm Air Heat Won't Finish

If your heating system is past forced warm air (a furnace arrangement) so bank check 2 switches that can cause the blower fan to run continuously even if the furnace is non heating the air:

• FAN WONT Cease - THERMOSTAT SWITCH - separate switches right on the room thermostat (photograph at far left) can turn the blower fan on continuously. If you are having problem finding switches on your thermostat

  Come across THERMOSTAT SWITCHES, EXTERNAL.



• FAN WONT Finish - LIMIT SWITCH - a manual button-pull switch right at the limit command in the air handler (photo at close left) can gear up the blower fan to run continuously. If you are having trouble finding the blower assembly limit switch

  See FAN LIMIT SWITCH.

While you may find skilful reason to proceed the blower fan running continuously (discussed at BLOWER FAN CONTINUOUS OPERATION) for now, to diagnose the problem brand certain that both of these switches are set to FAN OFF.

Watch out: not all forced warm air furnace heating systems have a Manual-On switch on the limit switch, and not all thermostats include a FAN-ON switch on the thermostat.

All Heating Systems: forced air, warm air, hot water, steam, heat pump, electric: stuck "on" step ii - continued

Disconnect the thermostat from the heating or cooling organisation - at the heating or cooling equipment .

Information technology's easy to isolate the room thermostat and its wiring from the heating or cooling system: we simply remove the two thermostat wires right at the master control for the heating or cooling system involved. Typically the two thermostat wires are cherry and white and are connected in the controller to terminals T1 and T2.

Our photo (left) shows the red and white thermostat wires connected to a heating boiler aquastat control - look at the top left corner of the photo. [Click to enlarge this or whatsoever photo or nautical chart seen at InspectApedia.com]

• If the heating system stops then the problem is most likely the thermostat setting,

  come across THERMOSTAT Calibration,

  or concrete THERMOSTAT WIRE CONNECTIONS, or external influences like position of the thermostat on the wall, exposure to drafts, etc.

  Continue to Step 3 below.

• If heating or cooling system keeps running (more than a couple of minutes if you lot accept warm air heat), something else is wrong. Since nosotros have eliminated the thermostat nosotros need to check for damaged or shorted thermostat wires. Go along to Pace iv below.

OK so it'south non always every bit trivial as I just said. Multi-zoned heating systems may hateful you have to follow the private thermostat's wires to find merely which control they operate.

If you are diagnosing a heating system that is controlled by a single room thermostat, then at that place will exist one wall thermostat, one pair of wires that run between the thermostat and a main heater or air conditioner controller, and one primary controller at the heater or air conditioner.

or a FAN LIMIT SWITCH for warm air oestrus (furnaces).

An air conditioner or heat pump will be controlled by thermostat wires connected to a control lath or relay in the air handler and/or compressor/condenser unit of measurement.

Only in multi-zoned heating systems there may exist multiple hot water zone valves or multiple air duct zone dampers. In those systems you volition need to follow the individual problem thermostat wires to the specific controller such as an private hot h2o heating zone valve to make the disconnection nosotros discuss hither.

Keep in mind that a zone valve tin become stuck in the Open position or it may even exist manually latched "open" to continue to allow oestrus to menses.

See ZONE VALVES, HEATING

Our photo higher up shows a rats nest of wires at an older hot h2o heating system zone valve. Two of these, red and white, will be coming from the thermostat and will tell the zone valve to open on a telephone call for estrus. Additional wires from the zone valve tell the circulator pump to run.

Many room thermostats for heating and cooling take more than 2 wires connected to the thermostat. Merely in just about every instance, only two wires are actually beingness used to turn the heater, air conditioner, or heat pump ON or OFF.

Assistance in sorting out thermostat wires is provided in our articles starting

at THERMOSTAT WIRE CONNECTIONS

and at THERMOSTAT WIRING Colour CODES

and at SHORTING THERMOSTAT WIRES to ID R W B.In those articles you'll besides observe thermostat wiring diagrams and details for just virtually every type of room thermostat.

Step 3: check for damaged thermostat wiring

Disconnect the thermostat wires at the thermostat : when the estrus is on and running and the thermostat is set to say 68F, when the room reaches 68F (measured at the thermostat on its scale), merely disconnect the thermostat wires right there at the thermostat. (See our warning at Footstep 2.)

Our photo (left) shows the simplest instance: a cerise and white wire from the wall thermostat turn a heating unit on (if they are connected past the thermostat or manually by touching them together) or off if they are disconnected.

Pulling the thermostat off of its mounting plate in this instance accomplishes "disconnect the thermostat wires at the thermostat" instruction.

Since a room thermostat is basically an ON-OFF switch that calls for heating or cooling in response to room temperature, when we disconnect the thermostat itself, that'due south the same as Non calling for heating or cooling.

• If the heating or cooling system stops then the problem is about likely the thermostat setting, so

  seeTHERMOSTAT CALIBRATION,

  and seeTHERMOSTAT WIRE CONNECTIONS - at the thermostat, external influences similar position of the thermostat on the wall, exposure to drafts, etc., OR the thermostat itself is defective.

  • For heating problems check that you were setting the thermostat all the way Downwardly and that room temperature is ABOVE the thermostat Fix temperature.
  • For warm air heat check that you lot accept non set up the fan control to ON at the thermostat

    (FAN ON AUTO MAN Thermostat Switch) AND that y'all have non set the fan control to total fourth dimension ON at the fan limit switch at the furnace

    (FAN ON-Machine or ON-Human ). If the air handler, blower unit, or fan won't finish,

    see FAN WONT Stop - THERMOSTAT SWITCH

  • Some room thermostats include a "safe" fashion that will phone call for heating at a pre-set temperature should the system lose power. If the thermostat requires batteries to operate, exist sure that information technology has new fresh batteries installed.
  • For cooling bug check that yous were setting the thermostat all the way UP and that room temperature is Beneath the SET temperature.
  • And if the cooling system air handler, blower unit of measurement, or fan won't terminate, besides

    run across FAN WONT End - THERMOSTAT SWITCH

• If the heating or cooling organization does non stop, after yous disconnected the thermostat wires at the thermostat, then disconnect the thermostat wires at the heating or cooling equipment  again as nosotros described

  at STEP two

  • If the heating or cooling organisation stops so most probable the thermostat wiring is damaged, probably shorted together. Shorting the thermostat wires together is the same as a thermostat calling for the heating or cooling system to run.

    If you cannot discover and fix the shorted thermostat wire fault (check first around the wall thermostat and effectually the primary controller at the other end of the same wires) you'll need to re-wire the thermostat.

  • If the heating or cooling system does not stop so the trouble is not the thermostat and not the thermostat wiring.

    Get to STEP 4

Footstep 4: what to practice when the problem is not in the thermostat or thermostat wiring

Turn Off Electrical Ability to the Heating or Cooling Equipment. Call your heating or air conditioning service company for farther diagnosis and repair help.

The equipment should End immediately.

Details well-nigh this switch are

at ELECTRICAL Power SWITCH FOR Rut

Scout out: Don't cycle heating or cooling equipment ON and OFF rapidly using the electric power switch or any other control.

For heat troubleshooting, expect at to the lowest degree five minutes between on-off cycles;

For cooling organisation troubleshooting wait at least fifteen minutes to minimize the chance of equipment damage.

On rare occasions malfunctioning controls on heating equipment may go along to feed fuel to an oil or gas burner, requiring that fuel also exist shut off. Turn off the fuel supply following instructions

at OIL or GAS SHUTOFFS.

• The master controller on the heating system may not exist working properly; on occasion we find that the primary control on a heating system, for example an internal relay, is sticking and keeps heat on even after the thermostat has said "enough".

  Depending on the type of estrus your building uses your service person will check one or more primary or boosted heater controllers for a stuck relay or other defects.

  Details near the heating or cooling device controller operated by the thermostat depend on which type of equipment the thermostat is controlling, and are establish at

  • Banality CONTROLS & SWITCHES
  • FURNACE CONTROLS & SWITCHES
  • STEAM HEATING SYSTEMS & CONTROLS
  • A/C - HEAT PUMP CONTROLS & SWITCHES
• If the warm air heating or ac or heat pump air handler, blower unit, or fan won't finish, run across these 2 diagnostic procedures:
  • FAN WONT Terminate - LIMIT SWITCH - a manual push button-pull switch right at the limit control in the air handler can set the blower fan to run continuously
  
  
  • FAN WONT Terminate - THERMOSTAT SWITCH - split switches right on the room thermostat can plow the blower fan on continuously

Lookout out: as we warned earlier, warm air heat blower units behave differently than hot water or steam estrus systems: to avert impairment to the heat exchanger the air handler or blower unit of measurement will normally proceed running for a infinitesimal or even a few minutes after the thermostat has stopped calling for rut.

For warm air heating systems, give the system a few minutes to shut down.

• Other causes of continued commitment of united nations-wanted rut are detailed

  at HEAT WON'T Plough OFF.

Examples of Diagnosing Too Much Heat or Heat Won't Plough Off - starting at the room thermostat

Reader Question: how practise I fix a thermostat that I accept to fix lower than the level of heat I desire?

My traditional honeywell simple dial-type thermostat on the wall has 2 pointers and two temp. scales. However I have to set it on threescore degrees to get heat temp to 70 degrees. What can I do? It was working fine until my condo changed the air/heating system this summer. - Jeannette ane/23/2013

Reply: check these reasons for a room thermostat that keeps calling for heat

Jeannette,

On most two-scale room thermostats, one calibration reads the electric current or actual room temperature while the other scale is the set temperature - and is adjustable.

When yous motion or adjust the thermostat to call for a unlike room temperature you volition see the scale arrow move to your new setting on the "set" scale.

You are describing having to set the thermostat lower (60F) than the desired temperature (70F) to get the proper level of oestrus in your home. In other words, yous say that the room gets also hot - hotter than you asked-for. Here are some things that would cause that problem:

• The thermostat or its wires have been damaged and are non reliably signaling the heating system primary controller.

  I wouldn't commonly place this guess first, but as you lot think the problem began after someone worked on the system information technology's worth a check.

  Expect for a loose connection or intermittent short in wiring. For example if 2 thermostat wires brusk together that's the same as constantly calling for heat.

• The thermostat is beingness blocked from properly sensing room estrus. That could be due to movement of the warm air supply registers to a new, more afar location, or more often, due to article of furniture, drapes, or even dust and crud that block the air inlet openings around the thermostat that allow it to sense room temperature.

  Dust can also interfere with moving parts in older jump-type thermostats.

• The thermostat is tilted out of level. If the thermostat is an older mercury-bulb blazon then it needs to be level on the wall.
• The thermostat is located on a cold outdoor wall or where cold air blows on it; if your thermostat was not moved and is on an interior wall and in a draft of common cold air, this isn't probable to exist the cause of the problem y'all describe.
• The primary controller on the heating arrangement is not working properly; on occasion we notice that the chief control on a heating system, for instance an internal relay, is sticking and keeps oestrus on even after the thermostat has said "enough".

  This is easy to check. When the heat is on and running and the thermostat is set to say 68F, when the room reaches 68F (measured at the thermostat on its scale), just disconnect the thermostat wires right there at the thermostat.

  If rut keeps running (more than than a couple of minutes if y'all have warm air heat), something else is wrong.

• There is another problem we haven't thought-of.

Reader Question: possible shorted thermostat wires

Our furnace thermostat failed afterward an side by side water heater installation. I noticed that wires were pinched between the water heater and the gas pipe.

Afterward I loosened the safety straps and freed the wire, the thermostat works. (I reset the furnace).

Were squished wires the cause of a temporary brusque and will the wires keep working if they are undisturbed? - Larry 8/2/xi

Reply: check for shorted wires and for thermostat transformer damage as well every bit for diddled fuse

Yeah it's surely possible that your thermostat wires were shorted. Now a short in those wires sometimes lets you lot off the hook with no trouble, since the wires and thermostat are basically an "on-off" switch that calls for estrus (or no heat).

But a thermostat wire short at the transformer could burn out the low voltage transformer that powers the thermostat and heating controls or maybe even damage the thermostat itself.

Notice and check the depression voltage transformer (often it'due south mounted near your furnace, on an electrical junction box, or it may be integral in your heater control unit).

See LOW VOLTAGE TRANSFORMER TEST

...

Continue reading at HEAT WON'T Plough OFF - topic home , or select a topic from the closely-related manufactures below, or see the complete ARTICLE INDEX.

Or see THERMOSTAT WON'T TURN OFF FAQs - questions & answers posted originally at this folio

Or encounter these

Recommended Manufactures

• CONTINUOUS BLOWER FAN OPERATION
• FAN ON AUTO MAN Thermostat Switch
• FAN WONT Stop - LIMIT SWITCH
• FAN WONT STOP - THERMOSTAT SWITCH
• Estrus WON'T TURN OFF - topic home
• SHORTING THERMOSTAT WIRES to ID R West B
• ZONE VALVES, HEATING - a stuck zone valve can proceed heat "on"

Suggested commendation for this web folio

THERMOSTAT WON'T TURN OFF at AuditApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: Article Alphabetize to HVAC THERMOSTATS

Or use the SEARCH BOX found beneath to Ask a Question or Search InspectApedia

...

Inquire a Question or Search InspectApedia

Try the search box just below, or if you prefer, postal service a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Note: appearance of your Comment beneath may be delayed: if your annotate contains an paradigm, web link, or text that looks to the software every bit if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Technical Reviewers & References

Click to Testify or Hide Citations & References

Publisher InspectApedia.com - Daniel Friedman

schipperslout1983.blogspot.com

Source: https://inspectapedia.com/heat/Thermostat_Stuck_On.php

Share this post