King S22 Thermostat: How Is Apartment Heat Controlled Without Using the Thermostat?

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How can an electric apartment heater with a King S22 line-voltage thermostat be controlled from outside the thermostat, and why do the heat settings seem to start working only above certain numbers?

Your heaters are probably not being controlled by an external device that changes the thermostat setting; what you are seeing is more likely an inaccurate, misadjusted, or damaged line-voltage mechanical thermostat, and the old King S22 is known to be imprecise [#21682195] [#21682196] [#21682200] These thermostats use a bimetal coil and have hysteresis, so two identical units can switch at noticeably different temperatures, and one may need internal calibration or replacement [#21682195] [#21682196] To prove the problem, put a thermometer next to the thermostat and compare the actual room temperature with the setpoint; if the measured temperature is several degrees off, the thermostat is out of adjustment or faulty [#21682193] [#21682195] [#21682200] If the building has outside control, it would usually be a load-shedding or power-disconnect scheme that shuts the heater off entirely, not one that changes the set temperature [#21682203] [#21682206] The safest fix is to have the landlord or an electrician service or replace the line-voltage thermostat; one reply recommends a modern KING ES120 or ES230 replacement depending on heater voltage [#21682193] [#21682191] [#21682198] [#21682207]

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#1 21682190 17 Mar 2019 21:52

Julie Nguyen Julie Nguyen

Anonymous
Post #1
21682190 17 Mar 2019 21:52

I live in a apartment, there are two King thermostats in my place, they are old model
S22 125/250/277 VAC
22 AMP SINGLEPOLE
LR 27080
E 47273

The heat was on at level 55 at any room temperature even in hot summer. Recently I don't know what the maintenance men did, they made the heaters work incorrectly. The heat in both rooms is only at 65 or higher levels, lower than that the heater don't work, they are off completely. I complained about that, they said the thermostats were sensitive with the room temperature, if the room temperature was higher than that level, the heat would be off. It not true, the thermostats did not work like that way before, I could turn them on in hot summer. They were quiet, no more answer.

They did the same thing with the stove, the grids are sometime extremely hot at low level. I requested to fix this problem twice, but it still happens rarely.

Can you please tell me how they can control the heat from outside, and how I can make the thermostats work correctly. This problem really make me uncomfortable, I have to bear very hot or cold, turning on and off all the time. If this topic is not covered by your site, please tell me somewhere else that can give me the answer.

Thank you for your time.

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#2 21682191 18 Mar 2019 22:12

Charles Lord Charles Lord

Anonymous

Post #2
21682191 18 Mar 2019 22:12

The old King S22 was notorious for being inaccurate. I suggest replacing with something like the KING ES120 or ES230 depending on whether your heater is 120 volt or 230 volt. See below:http://www.king-electric.com/pdfs/ES-ESP_WEB.pdfhttps://www.amazon.com/King-Electric-ES120-R-Electronic-Thermostat/dp/B000VZPUIQhttps://www.amazon.com/King-Electric-ES230-R-Electronic-Thermostat/dp/B000VZK5HMHope this helps!
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#3 21682192 18 Mar 2019 22:40

Julie Nguyen Julie Nguyen

Anonymous

Post #3
21682192 18 Mar 2019 22:40

Thanks for help.I would like to learn that if the heat can be controlled or set outside the apartment without a thermostat inside.I need to know the process before going to get new thermostats.Thank you.
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#4 21682193 19 Mar 2019 04:40

Elizabeth Simon Elizabeth Simon

Anonymous

Post #4
21682193 19 Mar 2019 04:40

Julie,It sounds as if you have some control of heat (on/off) but not as much as you want.
It's likely that the thermostat set point is out of adjustment. When you turn the heat on at minimum level (65) does the heat turn off at some point or does the temperature keep going up? You can check this with a thermometer.If the temperature does NOT reach a stable value, then your thermostat is broken.Perhaps a picture of the thermostat at a low setting next to a thermometer showing a much higher (or lower) value would convince your landlord of your complaint.
One thing you did not mention is what kind of heat you have. If it is steam or hot water then the maximum temperature will be controlled from outside your apartment but you should still be able to set a temperature.Oh, and this sounds like it is a line (mains) connected thermostat and unless you really know what you are doing, you should NOT attempt to replace it. I've replaced and adjusted thermostats BUT only low voltage ones. I recommend hiring an electrician for this.
#5 21682194 19 Mar 2019 18:10

Julie Nguyen Julie Nguyen

Anonymous

Post #5
21682194 19 Mar 2019 18:10

Thanks for answer.
It is non programmable thermostat,
there is no adjustment on it, and it is electric heat system. The heat
was on constantly at any level at any temperature. In winter time I
usually turned them at level 55 for the whole day except very cold days,
it kept me warm enough. I sometimes turned the heat on unintentionally
in hot summer, the thermostat worked fine.Now they are different.
The maintenance men had changed the new thermostats, I did not like
that kind, they replaced the old thermostat back, they don't work like
before. The heat is only on only at over 60, with the other thermostat
the heat is only on at over 70, and the heat is off completely under
those levels. Before this trouble, one thermostat had the same problem,
the heat was on only at over 70, and the maintenance man could fix it,
made them work fine like the other. I don't believe this kind of
thermostat depends on temperature, so I don't believe what they have
explained.
My question is how they can make this problem
happens, other hand how they could fix it. They are able to adjust the
thermostats, or they connect the thermostats with some device, then
control them I really want to learn this matter, if anyone can, please tell. Thanks
#6 21682195 19 Mar 2019 23:44

Elizabeth Simon Elizabeth Simon

Anonymous

Post #6
21682195 19 Mar 2019 23:44

Julie,I will try to explain.
Inside most simple thermostats, like what you have, there is a strip of metal in a coil. This strip changes size as the temperature changes. When you move the knob, you are rotating the coil. When end of the coil gets to the right position, then the heat turns on or off. So depending on where the knob is, the coil has to be at a different temperature for the heat to turn on.Now since this problem happened after the thermostat was replaced, it may be that the coil is in a different position with respect to the knob so you have to turn to a different position to have the same effect. It is also possible that the coil inside is damaged so that it no longer senses the temperature.I would recommend to put a thermometer near the thermostat, set the thermostat to just less than where it appears to turn the heat on. If the temperature measured by the thermometer gets much less (at least 5 degrees) than the setting on the thermostat then take a picture to show that the thermostat is not working.
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#7 21682196 20 Mar 2019 00:22

David Ashton David Ashton

Anonymous

Post #7
21682196 20 Mar 2019 00:22

Julie if it is a bimetal thermostat as Elizabeth says, you will usually hear a click when it switches on or off. You will hear this when you turn the knob - for instance if the heating is not on, and you turn the knob up, at some point you will hear a click and the heat should come on.One problem with bimetal thermostats is that they have hysteresis. Say you set it to 70 degrees - the middle position for the knob in your photo. If the temperature gets down to 70 degrees it should turn the heat on. However it might have to get to 75 degrees or more before it turns it off.
The other problem is that they are notoriously inaccurate - with one thermostat you might set 60 degrees to be comfortable, with another identical one you might set 70 degrees to get the same comfortable temperature. So don't expect the new thermostat to be exactly the same as the old one.The other possibility is that the maintenance guys have connected the wrong contact. Thermostats may have a Normally Open contact and a Normally Closed contact. one would be used to switch on the heat if it's too cold, the other will switch on the air conditioner if it's too hot. If you get them the wrong way round you'll get the heat or the air conditioning on all the time, depending what temperature is set. But if yours is the S22 it's a single pole model and won't have this problem. They do make an identical D22 which is double pole, ie switches both ways.
#8 21682197 20 Mar 2019 01:43

Julie Nguyen Julie Nguyen

Anonymous

Post #8
21682197 20 Mar 2019 01:43

Thanks for all explanations Elizabeth Simon: I have tried to open one thermostat to see a strip of metal as you describe, but I did not touch the core yet, should I detach it and change the coil? If possible, please give some picture showing it from the same kind of thermostat.
Thank you so much
#9 21682198 20 Mar 2019 03:01

Elizabeth Simon Elizabeth Simon

Anonymous

Post #9
21682198 20 Mar 2019 03:01

Julie,I do NOT recommend changing the coil. For one thing, the coils are custom for the type of thermostat so you would be unlikely to find the right one (and it would likely cost the same as a new thermostat).For another thing, I believe that your thermostat is powered off of the AC line voltage so it is likely that there would be hazardous voltage on the coil.I looked but could not find a picture of the type of thermostat you have.
#10 21682199 20 Mar 2019 15:30

Julie Nguyen Julie Nguyen

Anonymous

Post #10
21682199 20 Mar 2019 15:30

Thank you.I wonder if the heat is controlled from outside because of the fact:-
The maintenance man could fix one thermostat when the heat had been on
only at level 70 or above.Later the thermostat worked fine like the
other one, the heat was on at level 55. I was happy with the result.
- Few days later he changed two new thermostats (RoberShaw Climate 801 - Mechanical Line Voltage Thermostat), and the heat was on only at level 75 or above. I complained.- Second time it was reduced at level 70. I complained again.-
The third time, he made thermostats worked at level 65 or above. I
wanted lower level, they refused, then we agreed to replace the two old
thermostats back (King thermostat).Now one of thermostat works at above 60, and the other one works at above 70How
could they make all these happened? It is a big question for me. With
your explanations and confirmation from RoberShaw Climate, no way to
adjust the thermostats to change the heat level. I know that there are a
number of electrical professional people behind the maintenance men.
The other point, these guys don't want to do good job, they have tried
to come back my place for unnecessary reasons. Can they create some
device by themselves and use it in this case?
This new thermostat: RobertShaw Climate 801X0021 1803T
#11 21682200 20 Mar 2019 20:30

Elizabeth Simon Elizabeth Simon

Anonymous

Post #11
21682200 20 Mar 2019 20:30

Julie,From what you tell me, I don't think the heat is controlled from outside. But that type of thermostat is generally not that accurate. So if the temperature is 65, one thermostat may turn on when you turn it to 70 and the other may turn on when you turn it to 60. Some of them have an internal adjustment to make the set point (where it turns on) more accurate which is how the maintenance man was able to fix one of them.So what is the temperature in the apartment? Do you have a thermometer? Put your thermometer near the thermostat.
If your thermometer is reading 55 or lower and the heat is not on when set to 60 then you have basis for a complaint that the thermostat is not adjusted correctly.
#12 21682201 21 Mar 2019 20:13

Julie Nguyen Julie Nguyen

Anonymous

Post #12
21682201 21 Mar 2019 20:13

Elizabeth, thank you so much for your help.I don't have a thermometer yet, so I cannot check the exact temperature. Just leave it here.
Other
thing, just for learning: With the electric heat system like that (with
the same kind of thermostat), can people create a device or make a
connection to control the heat from outside if they can connect directly
to the outside power source?Thanks for teaching me.
#13 21682202 25 Mar 2019 16:46

Julie Nguyen Julie Nguyen

Anonymous

Post #13
21682202 25 Mar 2019 16:46

just for learning: With the electric heat system like that (with the same kind of thermostat), can people create a device or make a connection to control the heat from outside if they can connect directly to the outside power source?Can anyone help me, please?
#14 21682203 26 Mar 2019 02:24

Elizabeth Simon Elizabeth Simon

Anonymous

Post #14
21682203 26 Mar 2019 02:24

Julie,If they had access to the outside power source, they could prevent you from turning the heat on at all by shutting off the outside power source. You would see this as not being able to get heat during certain times (or at all). In this case the thermostat would work as normal when the power was on but not at all when the power was off.
If they had access to the wires from your thermostat (unlikely because the wires go directly to the heater), they could randomly turn the heat on or off without regard to the thermostat setting. But they couldn't control the temperature set point with just the wires.
#15 21682204 26 Mar 2019 02:38

Julie Nguyen Julie Nguyen

Anonymous

Post #15
21682204 26 Mar 2019 02:38

Thank you, Elizabeth. You are my great teacher.
#16 21682205 31 Mar 2019 05:16

Julie Nguyen Julie Nguyen

Anonymous

Post #16
21682205 31 Mar 2019 05:16

I just found out that there is a Picmicro schematic and code for a burst firing Triac type to replace a mechanical bi metal. AN-958
Is it possible to use embedded programming and a new created device to control the heat from outside for these two thermostats?
Thanks
#17 21682206 31 Mar 2019 13:49

David Ashton David Ashton

Anonymous

Post #17
21682206 31 Mar 2019 13:49

Julie you may have your heating system connected to a "load shedding" controller. Electricity companies use these to disconnect non-critical (well to them anyway!) load when they need to shed load, ie reduce the load on their systems. Heating and hot water systems are often connected to these - you may find them being switched off for anything from a few minutes to several hours during times of peak load on the electricity network.
#18 21682207 31 Mar 2019 14:00

David Ashton David Ashton

Anonymous

Post #18
21682207 31 Mar 2019 14:00

Julie that is a very nice little circuit but it's not really a thermostat as it has no way of turning the heat off once a certain temperature is reached. They in fact state at the end:"Other possibilities not given in this particular solution
include: 1. Temperature feedback 2. Self-calibration"
The PIC10F204 shown only has 4 I/Os which are all used, however you could use a larger PIC or tie a temperature sensor in with the pot on the GP1 pin to give you true thermostat function.The other problem here is that this circuit needs Line, Neutral and Load connections, most thermostats as you currently have would use only two of these, so you would have to have some rewiring done to use it.In these cases it's usually easier to buy a new mechanical thermostat.
#19 21682208 31 Mar 2019 19:38

Julie Nguyen Julie Nguyen

Anonymous

Post #19
21682208 31 Mar 2019 19:38

Thanks for patience and explanation. The old King thermostat and the new Robert Shaw thermostat have the same problem. The heat is on at a certain level, and it is never off by itself. The heat is off once turning lower level, and is never on again at that level. It does not matter old or new thermostat. Suppose I have the same two kinds of thermostat, the same above circuit I showed. Is it possible to make the same heating working as I described?Suppose the circuit does not make the heater working in that way, is there other possibility way to make the same case happens?Thanks for your time.
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Topic summary

✨ The discussion centers on issues with old King S22 line-voltage thermostats controlling electric heating in an apartment. The thermostats, rated 125/250/277 VAC and 22 AMP single-pole, previously allowed continuous heating at low settings regardless of room temperature. After maintenance interventions, the heaters only activate above certain higher thermostat settings (e.g., 60 or 70), with no heat below these thresholds, deviating from prior behavior. The thermostats are simple bimetal coil types without programmable or adjustable set points. The problem persists with both King S22 and replacement Robert Shaw Climate 801 mechanical line voltage thermostats. Explanations include thermostat inaccuracy, possible misalignment or damage of the bimetal coil, and hysteresis effects causing different turn-on temperatures. It is unlikely that heating is controlled externally beyond power supply interruption or load shedding by the utility, which can disable heating entirely but not adjust set points remotely. Embedded microcontroller-based triac control circuits (e.g., PIC microcontroller burst firing designs) were discussed as potential advanced replacements but require rewiring and temperature feedback sensors to function as true thermostats. The consensus is that the thermostats themselves are the main control points, and external control of set points without internal thermostat adjustment is improbable. Testing with a thermometer near the thermostat is recommended to verify actual temperature versus thermostat setting. Replacement with more accurate electronic thermostats like King ES120 or ES230 is suggested for improved control.
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FAQ

TL;DR: Old line‑voltage thermostats can differ by about 10°F in turn‑on point, and, as one expert said, “that type of thermostat is generally not that accurate.” [Elektroda, Anonymous, post #21682200] Why it matters: This FAQ helps renters diagnose and document heat-control issues with King S22 and similar line‑voltage thermostats.

Quick Facts

King S22 is a 22 A, single‑pole line‑voltage thermostat (125/250/277 VAC), typical for electric baseboard heat. [Elektroda, Anonymous, post #21682190]
Symptom pattern reported: heat only starts at dial marks ~65–75 and never cycles at lower marks. [Elektroda, Anonymous, post #21682199]
Mechanical bimetal stats have hysteresis; one post notes on at 70°F, off near 75°F. [Elektroda, Anonymous, post #21682196]
Some models allow an internal calibration tweak to align dial and actual temperature. [Elektroda, Anonymous, post #21682200]
Utilities may install load‑shedding controls that temporarily disable electric heating during peaks. [Elektroda, Anonymous, post #21682206]

How is my apartment’s electric heat controlled if I don’t touch the thermostat?

With line‑voltage baseboard systems, the thermostat directly switches mains to the heater. If someone cuts power upstream, heat won’t run regardless of the dial. However, outside control cannot change your thermostat’s set point; it only enables or disables power. “They couldn’t control the temperature set point with just the wires.” [Elektroda, Anonymous, post #21682203]

Why do two identical thermostats turn heat on at different dial numbers?

Mechanical bimetal thermostats vary in accuracy. One may energize at a dial mark of 60°F while another needs 70°F. That’s normal manufacturing tolerance, not necessarily tampering. The poster summarized it plainly: “that type of thermostat is generally not that accurate.” [Elektroda, Anonymous, post #21682200]

What is hysteresis in a bimetal thermostat, and why do I hear a click?

Hysteresis is the intentional temperature gap between ON and OFF. You might set 70°F, hear a click when heating starts, and another when it stops near 75°F. The click is the switch actuating as the bimetal moves. This prevents rapid cycling but can feel imprecise. [Elektroda, Anonymous, post #21682196]

Can maintenance adjust my thermostat so the dial matches room temperature?

Many mechanical stats include an internal set‑point calibration. A tech can tweak it so the click aligns better with actual temperature, improving comfort and repeatability. If the room is 55°F and a 60°F setting doesn’t call for heat, you have solid grounds to request adjustment. [Elektroda, Anonymous, post #21682200]

How can I document that my thermostat is miscalibrated? (3‑step how‑to)

Place a thermometer beside the thermostat and let the room stabilize.
Set the dial just below where heat usually turns on; note the thermometer.
If the reading is 5°F or more below the dial and no heat, photograph both and share with management. [Elektroda, Anonymous, post #21682193]

Is it safe to open or repair a line‑voltage thermostat myself?

Avoid servicing internal parts. Line‑voltage thermostats carry hazardous mains on their components, including the sensing coil in some designs. Replacement or calibration should be done by a qualified electrician to prevent shock, fire, or code violations. [Elektroda, Anonymous, post #21682198]

Could the maintenance team have wired something wrong?

If you had a double‑pole thermostat (e.g., D‑series), miswiring to the wrong contact could cause odd behavior. The King S22 is single‑pole, so that exact mix‑up doesn’t apply. Still, incorrect line/load connections can cause no‑heat or always‑on symptoms. [Elektroda, Anonymous, post #21682196]

Why did a new Robertshaw 801 behave like the old thermostat?

Your reports show the Robertshaw 801 also only heated above ~70–75. That suggests system calibration or wiring issues rather than one defective brand. Swapping back to the King with similar results supports this diagnosis. Documenting thresholds helps the technician target the fault. [Elektroda, Anonymous, post #21682199]

What’s a good replacement for an aging King S22?

A responder recommended KING ES120 (120 V) or ES230 (240 V) electronic thermostats. These models improve accuracy over old bimetal designs. Match the voltage to your heater rating plate. Professional installation ensures correct line/load connections and compliance. [Elektroda, Anonymous, post #21682191]

Can the utility or landlord throttle my heat remotely?

A load‑shedding controller can interrupt power to heaters during peak grid demand for minutes to hours. You’d see heaters disabled regardless of the dial. It won’t change your dial’s set point, only availability of power. Ask management if such a device is installed. [Elektroda, Anonymous, post #21682206]

Can a microcontroller and TRIAC board replace a mechanical thermostat?

Yes, but the example circuit cited lacked temperature feedback and required Line, Neutral, and Load wiring. It would need redesign or a larger MCU to add sensing and safety features. Buying a listed thermostat is simpler and safer for apartments. [Elektroda, Anonymous, post #21682207]

Why does the heat never shut off once it finally starts?

That behavior points to miscalibration, sticking contacts, or wiring that bypasses proper sensing. If lowering the dial stops heat but it won’t restart at that mark, photograph the dial and thermometer to prove the fault for service escalation. [Elektroda, Anonymous, post #21682208]

What is a line‑voltage thermostat?

It directly switches mains power to the heater, unlike low‑voltage HVAC thermostats that control a separate relay. Models like King S22 are rated 22 A at 125/250/277 VAC and mount on the room wall feeding baseboard heaters. [Elektroda, Anonymous, post #21682190]

What do “single‑pole” and “double‑pole” mean here?

Single‑pole breaks one conductor; double‑pole breaks both. Double‑pole offers full isolation when off. Your S22 is single‑pole; the similar D22 is double‑pole, which can change wiring options and failure modes if misconnected. [Elektroda, Anonymous, post #21682196]

I think the stove also overheats at low settings—related?

It’s likely unrelated. The thread focuses on heating controls. Electric range controls use different thermostats or infinite switches. Report the stove issue separately and request an appliance technician to inspect and document it. [Elektroda, Anonymous, post #21682190]

Can outside power control fake a different temperature set point?

No. Cutting or restoring power only enables or disables heating. It cannot shift the temperature at which your thermostat clicks. Only calibration, component faults, or thermostat replacement change that threshold. [Elektroda, Anonymous, post #21682203]