Talk:Thermostat

Energy Saving
I work for honeywell heating controls. I would like to add some general non-biased information about the energy saving benefit of fitting a room thermostat to a domestic central heating system. At the moment this is not mentioned on the page. I have tried adding it on but it was removed.

The energy savings trust state on their website that the turning your thermostat down by one degree can save up to 10% on your bill. This is a key fact that should be on this page.

Another even more important fact is that the majourity of domestic energy consumption is from heating and hot water (see the Domestic Energy Consumption page on Wikipedia).

I also suggest there is a picture of a modern thermostat at the top of this page and the one from the 1960s is moved into the history section.


 * If you want to contribute you are welcome but please keep in mind some things: All contribution have to be cited (WP:RS) and must be relevant to the topic. Energy saving would be beyond the scope of a thermostat article. Energy would belong in an energy saving article.
 * I deleted your contribution "Fitting a room thermostat to a domestic central heating system will reduce it's energy consumption." Because it is very vague, uncited and not relevant to the article. Also, I think it is wrong. Merely adding a thermostat is not enough; it would have to be wired correctly and the setting managed properly before any such effect could be stated. HumphreyW (talk) 10:49, 23 December 2010 (UTC)

Thanks. The key function of a domestic room thermostat is to save energy. I therefore believe it is relevant to state this on the page. If I add a comment stating this with a link to the page on the energy savings trust website that backs this up will it be removed? Energy Savings Trust link: http://www.theenergysavingtrust.com/Easy-ways-to-stop-wasting-energy/Stop-wasting-energy-and-cut-your-bills/Tips-to-help-you-stop-wasting-energy/Top-ten-tips — Preceding unsigned comment added by Jessica Clamp (talk • contribs) 11:03, 23 December 2010 (UTC)


 * I doubt that the key function of a domestic room thermostat is to save energy. More likely the key function of a domestic room thermostat is to control a heating/cooling system and set the room to a comfortable temperature. This is entirely independent of saving energy. HumphreyW (talk) 11:10, 23 December 2010 (UTC)

Please see quote below from the BBC News as well as Energy Savings Trust stating that a domestic room thermostat does save energy:

Turning the thermostat down by 1C can cut more than 10% from the average central heating bill. – BBC News http://news.bbc.co.uk/2/hi/uk_news/6076658.stm

I really feel this is an important message that is relevant to this page. — Preceding unsigned comment added by Jessica Clamp (talk • contribs) 11:46, 23 December 2010 (UTC)


 * But it is not the thermostat that is saving energy, it is the person controlling it that is saving energy. I could also say that an ordinary on-off switch is an energy saving device: By turning something off I am saving energy. But that does not make the primary function of the switch to be for saving energy. Indeed someone can use a switch (or thermostat) to waste energy by turning something on for more time. Plus the advice to turn down the temperature is incorrect for other parts of the world, like in the tropical zones where cooling is more costly. I think that the energy saving topic is not relevant to this page. Perhaps there is an energy saving page where your links might be more relevant? HumphreyW (talk) 11:58, 23 December 2010 (UTC)

History?
Is it possible to have some material about the history of the thermostat? Thanks A.S. Brown 04:23, 17 August 2005 (UTC)

It might be good to add a note on when/where the name Thermostat originated? Ilent2 (talk) 03:31, 23 June 2016 (UTC)

The first electric thermostat was invented in 1883 by Warren S. Johnson. http://www.america.gov/st/business-english/2008/July/20080710104405saikceinawz0.5803339.html

http://www.johnsoncontrols.com/publish/us/en/about/history.html

[JWN55] 10/3/09 2:21 AM EST

Fancy units operating from 24vac
I've changed the article to state that some digital units can operate directly from the 24vac thermostat circuit and do not require batteries (except possibly to provide backup against power failures). This is true and was also true of good-old mechanical "clock thermostats" before the fancy digital units. This is accomplished one of three ways that I'm aware of:


 * An additional wire provides a return path for the 24vac, allowing the thermostat to have a constant source of power whether it is calling for heating/cooling or not.


 * A rechargeable battery is charged from the circuit when the thermostat is not calling for heating/cooling and powers the unit when the thermostat is calling (and has therefore shorted its two input wires).


 * The thermostat is powered from the voltage on the circuit when the transformer isn't calling and is powered from the current flowing in the circuit when the thermostat is calling. (Yes, I've actually seen this!)

Atlant 17:08, 9 February 2006 (UTC)

But what IS a Thermostat??
Do you think that we could possibly have a better, simple explanation of what a thermostat is before the article goes on to explain various types of thermostat and how they work? Which, frankly most people who want to know what it is won't be interested in?

What defines an object as being a thermostat? What does an object have to have/do to be a thermostat? Is the timer control on my central heating a thermostat?

Imagine an 11 year old kid was wanting to make a thermostat for a science project - what would they need to do? Must it control a system to be a thermostat or can it simply act alone measuring temperature?

These are questions I would still like answered after looking the word up.

Cheers —Preceding unsigned comment added by 212.127.30.114 (talk • contribs) 15:00, 30 August 2006


 * I'm afraid he (the kid) can't do it, since there;s welding involved in making one —Preceding unsigned comment added by 68.4.65.17 (talk • contribs) 19:26, 22 September 2006

Wiktionary says: "a device that automatically responds to changes in temperature by activating a heating or cooling system to maintain the temperature at a desired setting." Therefore a thermostat is only part of a servomechanism or control system which regulates heat. In your home, the household furnace and air conditioner controlled by the thermostat are the rest of the servomechanism. John Harvey, Wizened Web Wizard Wannabe (talk) 16:32, 5 June 2011 (UTC)


 * I totally agree with the need to define a "thermostat" before wasting time writing anything else about them. The Wiktionary definition is ambiguous. What we want to see is something like....."a thermostat is a subsystem that might comprise a switch and a temperature sensing unit, such that the switch activates a cooling system whenever a measured temperature reaches (and rises above) a manually-set temperature". Or something like that. So the thermostat could be considered as a "part" of a temperature regulating system. And the performance of the whole temperature regulating system will depend on how the thermostat subystem is controlled. If clear definitions are provided, then everybody would at least be able to understand what a thermostat actually is. Or if there are various definitions, then just provide details about the various definitions - giving unambiguous examples.KorgBoy (talk) 02:55, 31 July 2017 (UTC)

Drake and Josh
I was wondering which kind was the thermostat in one mummii i love you of the drake and josh episodes ? cuz in that one we see the inside of it and cables were prominent since they were being welded, at first I thought it was a bimetallic thermostat since the cable maybe was a bimetallic strip and was getting modified ur the bestto only cool, but maybe it was a heat pump and the cool wires were being joined with other cool wires instead of heat wires thus making the heat uneffective therefore causing turning up the heat impossible. But maybe it had only two wires, or it had a thermocouple, but surely the thermometer was in one way blocked to keep from heating and it defintely couldn not have been a digital thermostat —Preceding unsigned comment added by 68.4.65.17 (talk • contribs) 19:34, 22 September 2006


 * Say what? Is this English? &mdash;QuicksilverT @ 17:38, 29 June 2009 (UTC)

H.L. Mencken
Here is an essay commenting on the history from January 1931. Maybe some of this should be placed into the article.--Kalmia 20:59, 16 November 2006 (UTC)

http://www.bizbag.com/mencken/menktherm.htm

THE THERMOSTAT ''... Of all the great inventions of modern times the one that has given me most comfort and joy is one that is seldom heard of, to wit, the thermostat. I was amazed, some time ago, to hear that it was invented at least a generation ago. I first heard of it during the War of 1914-18, when some kind friend suggested that I throw out the coal furnace that was making steam in my house and put in a gas furnace. Naturally enough, I hesitated, for the human mind is so constituted. But the day I finally succumbed must remain ever memorable in my annals, for it saw me move at one leap from an inferno into a sort of paradise. Everyone will recall how bad the coal was in those heroic days. The patriotic anthracite men loaded their culm-piles on cars, and sold them to householders all over the East. Not a furnaceman was in practise in my neighborhood: all of them were working in the shipyards at $15 a day. So I had to shovel coal myself, and not only shovel coal, but sift ashes. It was a truly dreadful experience. Worse, my house was always either too hot or too cold. When a few pieces of actual coal appeared in the mass of slate the temperature leaped up to 85 degrees, but most of the time it was between 45 and 50.''

''The thermostat changed all that, and in an instant. I simply set it at 68 degrees, and then went about my business. Whenever the temperature in the house went up to 70 it automatically turned off the gas under the furnace in the cellar, and there was an immediate return to 68. And if the mercury, keeping on, dropped to 66, then the gas went on again, and the temperature was soon 68 once more. I began to feel like a man liberated from the death-house. I was never too hot or too cold. I had no coal to heave, no ashes to sift. My house became so clean that I could wear a shirt five days. I began to feel like work, and rapidly turned out a series of imperishable contributions to the national letters. My temper improved so vastly that my family began to suspect senile changes. Moreover, my cellar became as clean as the rest of the house, and as roomy as a barn. I enlarged my wine-room by 1000 cubic metres. I put in a cedar closet big enough to hold my whole wardrobe. I added a vault for papers, a carpenter shop, and a praying chamber.''


 * Amusing anecdote, but probably has no place in the article, except as a footnote or external reference. &mdash;QuicksilverT @ 17:38, 29 June 2009 (UTC)

Comment about oil heating
I think it would be a good idea to mention on Oil Furnaces that use hotwater to heat the house, the thermostat operates an electric valve to get water flowing. —The preceding unsigned comment was added by 172.164.79.146 (talk) 19:35, 7 January 2007 (UTC).

Use of Bimetal thermostats
They are still widely used at least in The Netherlands. I edited a bit and slapped on a template. László 13:01, 25 January 2007 (UTC)


 * I think it's safe to say they're still widely used everywhere. There are still plenty of folks worldwide who aren't cutting-edge technologists and Wikipedians ;-).


 * Atlant 13:15, 25 January 2007 (UTC)

Suggestions
I am certain there is good deal more information about thermostats available. Discussions of the manufacturing of bimetallic elements such as dimpling disks, various schemes of using this phenomena, disk hysteresis, designing temperature ranges, and methods of power circit activation. The thermostat description "The power through the thermostat is provided by the heating device and may range from..." is unclear to me. Please revise.

—The preceding unsigned comment was added by Drkeene (talk • contribs).

What about setpoints? One obviously sets the tempature, but this article does not explain how to set a thermostat's upper/lower ranes (hysteresis?); i.e. at what tempatures the furnace (for example) turns on and then off (some amount below or at the set tempature and some amount above). 72.72.54.98 (talk) 08:39, 23 December 2008 (UTC)

Removed sections
I removed the 'Chronothermostat' and 'Phone Interface' sections, because both lacked any... content. Both simply said "This section is a stub". Just posting here, in case anybody was using those as placeholders for future content. Ahanix1989 13:24, 22 April 2007 (UTC)

PID Controller
The explanation of how a PID controller works is not correct.

A standard thermostat is "P". The heating or cooling action is turned on based on whether the temperature is less than or greater than the set point.

With a PID system, the actual set point of the thermostat is modified slightly to improve the accuracy (reduce the error) with which the temperature matches the temperature which the user has set.

This is done by generation of two functions of the temperature.

I stands for intergal which is simply described as the error multiplied by the time the error has occurred. This is (algebraically) subtracted from the set point which will move the set point in the opposite direction from the error. The effect is that after a small error has occurred for a period of time that the system will be run to correct it.

D stands for differential which is simply described as the rate which the temperature is changing -- how much it changed during a measuring period. This is also (algebraically) subtracted from the set point. The effect is to turn the system off earlier than a standard thermostat would and by doing so to prevent overshoot.

The stability of a non-proportional system (on/off or staged) is improved by not operating I while the system is running and only operating D while the system is running.

Tyrerj 16:23, 6 June 2007 (UTC)

The D stands for derivative. See http://en.wikipedia.org/wiki/PID_controller [JWN55] 10/3/09 2:17 AM EST —Preceding unsigned comment added by 68.209.233.28 (talk) 06:16, 3 October 2009 (UTC)

Since the described effects of a PID-controller in the article were seriously misleading, I made a hotfix edit (2017-10-17)

3 wire mains thermostat
Some 240V bimetallic thermostats have 3 wires, live (in), neutral (in), and control (out). They also have a resistor (typically 220 kOhm) between the wall (high thermal inertia) and the bimetallic strip, which is turned on by the thermostat, and dissipates about 1/4 Watt. The purpose of this is to reduce hysteresis. When correctly installed, these work extremely well, however they are *not* compatible with modern 24V boilers. If such a thermostat is used in with a low voltage boiler, the resistor will dissipate negligible power (or may not even be connected). As a result, hysteresis can be about 4 degrees at the thermostat, and larger near the radiators, causing the temperature to fluctuate uncomfortably. —Preceding unsigned comment added by 87.194.171.29 (talk) 12:31, 30 July 2008 (UTC)

Pneumatic thermostats
The intro mentions pneumatic thermostats, but there is no mention of them in the article itself. Could somebody add some information about this type of thermostat? Normally I'd be bold and do it myself, but I don't really know how they work, and I haven't had much luck finding any sources on the web. Apparently they use air to send signals to the HVAC systems, and they seem to be common in large buildings, but that's as much as I've been able to figure out thus far. —BMRR (talk) 23:05, 29 June 2009 (UTC)


 * Upon further Googling, I found that there is already a stub -- Pneumatic thermostat. I would, however, suggest that it be merged with the main thermostat article. —BMRR (talk) 23:21, 29 June 2009 (UTC)


 * See discussion at Talk:Pneumatic thermostat, since the "discuss" link in the template points there. &mdash;QuicksilverT @ 17:09, 1 July 2009 (UTC)

The currently linked source for pneumatic thermostats includes this important bit of info: "...commonly used in chilled water air conditioning fan-coil units ... a properly tuned pneumatic circuit will respond to the temperature by opening the water valve to the exact position necessary to provide the correct amount of chilled water to the coil." It seems to me it would be useful to incorporate this into the article, can someone with better wiki-fu than I make this happen? As I understand it, this is saying that pneumatic thermostats are more "analog" compared to the fan on/fan off action of a typical household electronic thermostat. 38.121.96.73 (talk) 04:22, 10 October 2010 (UTC)

Wax pellet qualified with automotive to be more relevant
Wax pellet technology is also used in heating industry widely - so this clarifies this specialist entry. —Preceding unsigned comment added by Dougsim (talk • contribs) 18 September 2010

Chronothermostat

 * Chronothermostat redirects to Thermostat
 * Chronotherm redirects to Programmable thermostat

These need expanding into a section, if notable.  Captain n00dle \ Talk 12:57, 1 April 2012 (UTC)

How does a Thermostat Work?
Atconsul (talk) 14:57, 28 November 2013 (UTC) The most obvious omission here about the science and technology of thermostats is that the entry does not help anyone to understand how to use one.

Whilst people who do know how to use one will instinctively think this is so obvious that it doesn't need stating, the reverse is true: most people don't: their mental model of the device is that the rate of change of temperature demanded by the device is proportional to the difference between the actual temperature and the set temperature. Modern electronic and digital thermostats might choose to approach this behaviour, but the basic traditional device does not distinguish how different the actual and set temperatures are, it is a bang-bang, on/off device that either switches the circuit on or off until the set temperature is reached.

This is not a dry academic point. It ruins life in homes and offices all over the world where users are able to set the temperature themselves, because it results in thermostats being set to MAX on cold mornings. As stated above, this makes no difference to the rate of temperature increase, it just guarantees that the thermostat is no longer working as a thermostat at all, and will cause the room temperature to overrun, wasting money and ruining comfort and productivity. It also makes it likely that the user control will be de-activated altogether.

All the better, therefore, if Wikipedia can make a contribution by educating users about the real thermostat.

Atconsul (talk) 14:57, 28 November 2013 (UTC)

Update: users in my office have now attempted to control the overrun by turning on the air conditioning, so we are now generating heat so that we can actively pump it out into the atmosphere. Chances are the aircon thermostat has been set to MIN to do this. What hope planet Earth? Atconsul (talk) 14:07, 17 January 2014 (UTC)

Is Lux sponsoring this page?
There is so many references to Lux branded products in a pointless way. They aren't notable in any way, yet their products are all over the place on this page.

What gives? Why are we allowing shameless product promotion on wikipeida? — Preceding unsigned comment added by 2001:569:73F5:6600:FD20:E4F2:90DD:1550 (talk) 19:48, 11 June 2019 (UTC)

Contact configuration nomenclature
I don't know if this chapter is placed correctly, or if it should be more general. Also, whether the table is complete I don't know.

But in data sheet like this thermostat from [https://www.elfadistrelec.no/Web/Downloads/he/et/2455r_eng_datasheet.pdf Honeywell. Commercial Thermostats] COR and OOR are defined. Also, at a filter page Termostatbrytere (Thermostat switches) one can see 1NO, 1NC and 1CO used as filter criteria (in "Kontaktkonfigurasjon", "Contact configuration"). But the proper article should have better references. Øyvind Teig (talk) 16:49, 12 November 2019 (UTC)

Readability
Congratualtions on once again taking what are mechanically quite simple concepts and writing about them in complex-sounding academic terms that do nothing but baffle the average reader who is curious to find out. It is very lucky that I read a nice, simple English description of what an "anticipator" does and why or I would have been totally baffled by the description on here and probably given up. "To improve the comfort of the occupants of heated or air-conditioned spaces, bimetal sensor thermostats can include an "anticipator" system to slightly warm the temperature sensor while the heating equipment is operating, or to slightly warm the sensor when the cooling system is not operating. When correctly adjusted this reduces any excessive hysteresis in the system and reduces the magnitude of temperature variations. This is not only confusing, it isn't even totally accurate. Whereas the other anti-hysteresis controls allow the heat to rise ABOVE the temperature before shutting off, in this case it actually shuts the burner off before the target is reached, to allow the blower to pump the rest of the heated air into the living area. Otherwise the thermostat would shut off when it registered 70deg...and then the rest of the heated air would be pumped from the plenum into the living space. When properly adjusted, the anticipator shuts the burner off before the target point is reached, and then the remaining hot air brings it to the target point or slightly past. It is the mercury switch that performs the usual service of delaying the shutoff until it goes beyond the intial tripping point, to prevent rapid cycling. All the anticipator does is prevent the temp from spiking past the point the thermostat is set at every time the blower shuts off. It also allows the same thermostat to be used in varying sizes of houses, with varying sizes of furnace. They could build a delay into the thermostat to make sure it shut off a bit before the target temp, but how long varies on the size of the heating space and the size of the furnace. The adjustable anticipator allows them to use the same thermostat for a wide varieties of furnace and heating spaces, setting the delay longer for small areas, longer for larger areas (of course if the furnace is just too small for the area, the delay won't make any difference and it will just run constantly trying to heat it). The reason it heats the thermostat (this should be explained in the article, it won't be clear to everyone) is that by heating the bimetallic coil a degree or two, it makes the thermostat "think" that it's actually 70deg when it's only 68deg, and so it shuts off and allows the blower to make up the difference, resulting in an acutal temp of 70deg when adjusted properly. If turned up too high the furnace will shut down too soon and the area will never reach the desired temperature and cycle on radidly to again attempt to raise the temperature. If set too low the temperature will spike every time the furnace kicks on and you will use more fuel, for no purpose other than to repeatedly feeling overheated. I'm not quite sure I understand why one would want to heat the thermostat when it's running an AC unit...to make it shut off LATER and get colder? I'm not sure that is correct. Seems to me that it's more likely that if one is using the same thermostat for both AC and furnace that you would want to turn the anticiapator DOWN in the summer, negating the heat effect, lest it cause the AC to cool the house too much. Unless that's what you want, of course. As for why heat is always used, it's because it's simple and cheap to make a low-power heating element. It's much more difficult to cool something. There is no such thing as a "cooling element" yet.

Idumea47b (talk) 00:14, 25 January 2020 (UTC)
 * WP:SOFIXIT Meters (talk) 04:06, 25 January 2020 (UTC)

Thermostat Signals vs. Wire Colors
In the 1990s I did some contract-consulting work for a Canadian heating-cooling company. At that time, I remember talking to the field technicians about the general confusion with signal names vs. wire colors. "I was told" that early wire bundles did not have a lot of wire colors but that white was usually reserved for "warming" and that green made "the fan go" (so this is all mnemonic stuff). By the time that the heating-only installations also added cooling, the yellow wire (which was a spare) was used by default. Some people worried that it was possible to call heat and cool at the same time so "some companies" employed a mode wire to select "heat mode" or "cool mode" (then white just become "call the selected mode"). But some decisions are all about saving wires and this is when O was combined with B with one mode being the negation of the other. I was also "told" that "rc = return cool" while "rh = return heat". Why return? These systems never sent raw 24VAC power through the wires; power was sent from the 24VAC transformer to one side of the relays; then the thermostat closed the circuit between the signal wires and the return path. Why two signals? Many times the heating and cooling equipment were two different vendors (when they are not, these signals are strapped together in the thermostat). Anyone who has inspected a schematic wiring diagram in 2020 for thermostats without batteries (Honeywell Home uses the title "c-wire addendum") can see that the "C" wire is the raw power side of the 24VAC transformer (not "ground" as is labelled in the article but perhaps "common" might be more meaningful). If nobody objects within the next week, I am going to correct the description of signals "RH", "RC, and "C". Neilrieck (talk) 13:50, 25 November 2020 (UTC)