Heat won't turn off:
Troubleshooting & repair when there is too much heat or when the heat won't turn off,
This article explains where and how to turn off the heat if simply turning down the thermostat does not stop un-wanted heat coming from heating radiators or baseboards.
How to fix the problem of too much heat or a furnace, heat pump, boiler, radiator or steam boiler that won't turn off.
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I live in a rental property. It is a three floor house, which old school round honeywell thermostats on each floor. All three of these thermostats are turned down as low as they can go. It's nice out now, but our heaters still leak heat.
The landlords have told us we need to turn the heat off, that there is a "slidey switch" on each of the three thermostats to turn them off.
I live in New York, they live in colorado and don't specifically remember how to do it, even when I sent them cell phone pictures of the unit with the lid off.
The only "slidey thing" I see is beneath the thermostat cover (I removed it to look) - it is what you describe
Reply: Guide to Turning off the Heat in a Building - When the Radiators or Baseboards "won't turn off"
DO NOT try to turn the heat on or off by changing the adjustment shown in our photo and described by the question above. That's the heat anticipator not an on-off control for heat. The heat anticipator is a fine-tuning adjustment inside the thermostat and not something that a homeowner should change. The heat anticipator is explained
Just below we discuss several considerations in turning off un-wanted heat in a building. This article addresses problems with thermostat settings, non-working check valves or flo-control valves, and how to force the heat to "turn off".
Separately at RADIATORS we discuss the problem of individual radiator valves that don't operate to allow turning a hot water or steam radiator on or off.
Also see ENERGY SAVINGS in buildings.
Turning Off Heat at Thermostats that Set Temperature Only - Lack an "on-off" Switch
Thermostats contain an internal temperature sensor which compares the air temperature at the thermostat to the temperature called-for by the user, turning the cooling (or heating) equipment on or off as appropriate.
If with the cover on your thermostat (TT) looks like the Honeywell round thermostat shown at left, (discussed at THERMOSTATS) Then there is no "HEAT OFF" control on the thermostat itself.
This thermostat is adjusted by turning the clear plastic dial by grasping its outer ring. The upper temperature dial is the "set" temperature - the temperature you are asking to be maintained.
The lower temperature indicator dial is the "current room temperature" sensed by the thermostat. In our photo the room temperature is at 70 °F and the "set" temperature is below that, at 66 °F. In this condition the heating system should not be running to warm the building.
If this thermostat is set to a temperature above room temp the boiler (or furnace or steam boiler) will run until the thermostat is satisfied (and the room reaches or passes the "set" temperature on the thermostat.
So if you set the thermostat to a temperature below the room temperature, heat should be "off" and heat should soon stop coming out of radiators, baseboards, or air registers. If the heating system keeps on warming radiators or baseboards in this condition, we explain what to do about it in this article - below.
Locking Thermostat Cover Protects Against Thermostat Tampering
I have a question. I have a daughter. she is 45. she is a toddler mentally. i need to stop her from turning on the heat all the time. It runs the bill sky high. there are political problems that make certain known solutions not possible.
Too late for spanking, no known way to stop her from turning on the heat all the time, cannot shut the heat off with switches, cannot pay the bill, cannot shut off electricity to the heat, its definately an interesting concept.
I basically mentally in your mind picture this: i have a 4 year old toddler who can reach the heat, and like a deviant keeps turning the heat on, but it's not deviant behavior it's incorrect behavior, its happening because of her medical situation related to thyroid, because of politics there is no known way to stop my 4 year old from turning on the heat and stopping the bill from being sky high. i must stop the heat and the bill from happening from my point of view.
Also, i refuse to believe there is No way to stop this from happening; theres gotta be a way, but danged if i know or can think of it or a way to stop her or the heat. is this crazy? i refuse to believe there is no way to stop her or the heat. theres gotta be a way.........help me on this fellas what am i missing here. - Anonymous 10/24/2012
Maybe a password protected digital thermometer?
Reply: how to prevent thermostat tampering: install a locking thermostat cover
Check with your heating supplier and almost certainly they can provide you withnan inexpensive clear plastic cover that screws to the wall, has vents toilet the thermostat sense room air temperature, and can be opened to adjust the thermostat by using a lock and key. You see these locking thermostat cover set ups often in offices and commercial buildings. It's an easy add-on feature to prevent thermostat adjustments by people who should keep their mitts off.
For more about wall thermostats, take a look
Turning Off Heat at the Electrical Power Switch or Service Switch
If you want to turn off your heating system regardless of the temperature setting at the thermostat, and if the thermostat itself does not include an "off" switch (see the next description below) you can turn off the heat by switching off electrical power to the heating boiler or furnace.
To completely turn off the heating system, regardless of thermostat setting, you'd need to find the boiler or furnace "off" or "service" switch - an electrical power switch.
Usually there are two electrical switches controlling power to a boiler, steam boiler, or warm air furnace, one at the heater itself (for service people) and one at the entry to the utility room or basement where the heater is located, or somewhere in the living area near a stairwell or hall that goes to the heater.
Sometimes, but not always, these switches have a red cover.
See ELECTRICAL POWER SWITCH FOR HEAT for a description of the heat master on-off control.
Turning Off Heat at Thermostats that Include a Cool-Off-Heat Switch on the Thermostat
If your thermostat has a "Cool-Off-Heat" switch, such as those shown
If your home does not have central air conditioning it might still have a thermostat with these three settings.
To simply turn off the heat regardless of the thermostat's temperature setting, just set the slide switch to the "off" position (in the middle in our photo at left).
Incidentally, wrong temperature settings can also foul up delivery of cool air from an air conditioning system: for the thermostat to actually turn on the air conditioning system (if central air is installed) the thermostat switch must be in the "cool" position and the temperature set to a level below the ambient room air temperature at the thermostat location.
Why Are the Baseboards or Radiators Hot Even Though the Thermostat is Set Higher than Room Temperature? Un-wanted Gravity or Convection Circulation of Hot Water
If electrical power switch to a hot water heating boiler is in the on position
But for hot water heating systems (baseboards, radiators), other defects could cause or permit hot water to circulate through the heating system by "gravity" (convection, warm water rising on its own through the heating piping) even though the thermostat is not calling for heat.
The problem, if this is occurring, is usually that a check valve (photo above-left) (found internal to some circulator pumps, or external as a physical device) intended to prevent hot water from circulating on its own - when the circulator pump is off - is either set to a "forced open" position, or it has become defective.
If that's the problem (diagnosed by a heating and service technician) then the valve or circulator needs to be replaced. While waiting for that repair to be made, you can still turn off the heat, by turning off electrical power to the boiler.
See CHECK VALVES, HEATING SYSTEM for more about these devices.
What if Our Heating Boiler Also Makes Hot Water for Washing?
Watch out: if your heating boiler is also used to make domestic hot water for washing and bathing, through a tankless coil
If that's the case, but you're getting heat when you're not asking for it, then the check valve, flo-control valve, or similar problem (or a faulty thermostat itself) needs to be diagnosed and repaired.
How to Save Heating Cost & Air Conditioning Costs by Thermostat Adjustments
Substantial heating or air conditioning cost savings can be achieved by manually setting back your thermostat when the building is unoccupied or when occupants are asleep. The thermostat is set several degrees (or more) cooler during heating season or warmer during cooling season.
The settings of thermostat "mode" switches into "heating" or "cooling" and the use of other thermostat switches to control an air conditioning blower fan or heating system blower fan are discussed in detail
Lots of websites offer calculators that will tell you how much you'll probably save in energy costs for every degree you set back your heating or cooling thermostat. Just don't set the thermostat down so low that you suffer costly damage from freezing pipes in winter or mold from high humidity in summer.
Reader Question: our furnace won't turn off
We have temp on thermostat for gas heat set at 65. Heat just keeps running and running, never clicks off. When we shut the heat down from the thermostat, heat clicked off fine. When we turn the heat back on from thermostat and set to our desired temp, it just runs and runs and never clicks off. - Anon 12/25/11
Usually when a furnace won't turn off unless you turn down the thermostat that's a pretty good clue that the system is unable to warm the room enough to satisfy the thermostat. This can happen with an undersized system, in very cold weather, with windows open in the room, but it can also happen if something (a dirty air filter, constricted or damaged heating supply ducts) is restricting the delivery of warm air into the room.
Because some controls are used in common on hot water heat, hot air heat, and steam boilers, readers should see these other articles: see BOILER CONTROLS & SWITCHES
If your building uses warm air heat, see FURNACE CONTROLS & SWITCHES
If your building uses steam heat see STEAM HEATING SYSTEMS.
Continue reading at THERMOSTAT WON'T TURN OFF or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs)
Question: temperature sensor does not respond to the actual space temperature
(Jan 4, 2013) Nick said:
(Jan 16, 2013) Larry Morris said:
(Feb 18, 2013) Jay said:
(Jan 24, 2014) chike said:
Question: Peerless MI-05 boiler troubles blamed on the U.S. President?
(Apr 3, 2014) John said:
I'd start by disconnecting the thermostat wires at the boiler end. That will rule out a wire short that an cause the problem you describe. I've also seen this problem as an artifact of the primary aquastat. It's a potential for a fist-fight that's to be avoided IMO.
If you read the installation instructions for a Honeywell aquastat (like the R818x series) you'll see that the mfg wants you to use a heat conducting paste on the sensor when it's mounted in the sensor well on the boiler = thus assuring good thermal contact between the aquastat's temperature sensor and actual boiler temperature. The fellows like to skip this extra work and worse, will be very reluctant to go back and correct it as you'd have to R&R the whole assembly from the boiler in most cases. But that too could be at fault.
John also check the Aquastat settings.
(Apr 3, 2014) John said:
If you are not already speaking with the company's service manager, give that person a polite call and ask for help from someone more experienced. If there is no higher authority you're stuck with the guy you have or bailing and hiring someone else. Sorry.
(June 9, 2014) xenaon said:
I cannot relight the pilot - turn on the gas line, hold down the pilot valve - won't light.
I cannot find a way to turn on the Rheem Criterian II gas/AC unit. What else needs to be turned on? Thermostat (Honeywell) does not ignite the AC or fan or heat - but it could not possibly be the thermostat as the person who shut off the fan switch - also turned off the water heater.
Question: burners are lit & staying on, even though we are not calling for heat
(Sept 17, 2014) Edgar Cruz Sr said:
Check for shorted thermostat wires
Question: Landlord has tenant who complains heat won't go down
(Oct 4, 2014) Anonymous said:
I am very grateful for my landlord its very hot in here we have radiator s they should all have a leavle to shut off
(Dec 14, 2014) Anonymous said:
I took off the baseboard covers and showed her how the pipes are room temp and immediately get boiling hot when the thermostat calls for heat. My question is, could there be a tiny amount of hot water sneaking past the zone valve that almost doesn't register as hot when you touch the pipes, but still warm enough to keep heating the room? It's probably been averaging 20s-30s here in Minnesota lately.
She's on a third floor with units above below and on either side, but I can't imagine the residual heat from those units would heat hers to 75. I used to live there, but don't recall this problem.
Any help is appreciated.
If the room temp is high, say 75F, indeed I'd expect the baseboard to be close to that temp even if there is no call for heat.
You might be seeing some convection circulation if a flow control valve at the boiler is not fully closing when the circulator is off, or if a zone valve is not fully closing.
But I'd look for
- improper thermostat settings
Question: I've set my thermostat the the factory settings but it will not stop heating up.
(Dec 17, 2014) Anonymous said:
Anon have you tried the diagnostic suggestions in the article above? You may not be doing anything wrong yourself.
Question: Liz's apartment is way too hot
8 Jan 2015 liz the landlord said:
First we need to get clear what thermostat is controlling just what. I can't know the wiring of controls at your building from just your e-note.
When the thermostat in your apartment is set well below the actual present temperature, feel the radiators, convectors, baseboards - whatever is your heat source. If they are hot and thus are the heat source (as opposed to heat coming from a neighbour or other source) then I suspect a control or thermostat is mis-wired or the thermostat wires are shorted together somewhere, thus always calling for heat.
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