Inside a cheap eBay fridge freezer thermostat

[@CanadairCL44]

"This is where it bursts and squirts unknown chemicals everywhere"! Carry On Clive!

[@olipito]

I once cut one of those tube-wires, the fluid was pretty much reactive with humidity and almost set my lab on fire!

[@CanadairCL44]

@@olipito Alcohol based.

[@fallknight5405]

Sounds like the title of a 70's movie 'carry on Clive'

[@olipito]

@@CanadairCL44 thanks for the answer. Do you have more details on the chemistry of the fluid?

[@aaronshapiro2542]

same, but it was an oven one.

[@Namirred]

6:14 because it's cold it will be retracted in, said every man.

[@pear7777]

Clive doesn't, he starts working below 10°C

[@chrishartley1210]

3:35 and then Clive pulls Simon's knob off.

[@DrN007]

Like a frightened turtle.

[@CanadairCL44]

This brings back memories of when I was a quality manager, setting up inspection section procedures at a domestic gas boiler manufacturer, in the mid 1980's. Best job I've had in years!

[@IrishSkruffles]

Slightly unrelated: my father found previous work done on a commercial fridge, where the owners got a local handyman to fix it.. The handyman cut and joined a capillary pipe with a strip connector because he thought it was a wire and couldn't figure out why it still wasn't working...

[@bostedtap8399]

Brilliant!, You get what you pay for.

[@steveosshenanigans]

That’s gold 👍

[@DerMarkus1982]

I've witnessed sooo many people joining coaxial antenna cables that way, wondering why the signal's gotten even worse after their "repair"... But the capillary tube thing is new to me.

[@christiangeiselmann]

How can people be that dumb?

[@jumboegg5845]

Love your work Clive. The last thermostat you pull apart you refer to its calibration screw. I think that screw is actually the "differential" temp setting, it works like a sensitivity setting, by adjusting the tension on the spring mechanism. The user-adjustable knob sets the temp at which the thermostat turns off . The sensitivity setting adjusts the temp at which the thermostat turns on, which for fridges and freezers is fixed at about 3 - 5 degrees above the temperature set by the user.

[@snigwithasword1284]

"We don't know what it is, but here it is!" --99% of all online redistributers

[@jkobain]

Well, not every Chinese seller is even this sincere!

[@tomschmidt381]

I've found that out. Makes explaining and resolving problems very difficult. eBay tends to favor buyers but I sometimes think sellers get the sort end of the stick.

[@jkobain]

@@tomschmidt381 hahah, currently one seller on Ali ignores my messages after sending me the wrong item labelled as the one I ordered. Opening a dispute can help, maybe, but their immediate response was refusal explained like «delivered, ask your local post office or relatives about it». I mean… WTF? How could my local post office be responsible for a warehouse error?!

[@68pishta68]

@15:28 the knob does not rise and fall to the case, the red rotating wedge increases or decreases the force on the diaphragm lever changing its position and/or resistance to movement creating a manually variable switch on/off state. @20:31, you got it!

[@spokehedz]

BigCliveDotCom: Causing shipping managers everywhere to scream when they find out how much it costs to ship to the Isle of Man.

[@bluerizlagirl]

It costs more to ship goods to the UK mainland from Europe now we have reintroduced customs formalities, though .....

[@Somanathan-hj7ge]

You are practical as well as theoretical, very good sir

[@johndododoe1411]

The capillary full length sensing fridge thermostat is designed to be installed entirely inside the fridge, turning the knob only with the door open.

[@Mtematiks]

Thats true, but MOSTLY if you have a freezer inside, the eond of the tube is IN CONTACT wirh the wall of the freezer!

[@johndododoe1411]

@@Mtematiks Thermostat regulates compressor runtime to keep main fridge compartment at the set point , Supplemental freezing box gets whatever it gets by thermal design, not by touching any sensor .

[@PaulSteMarie]

The sleeving on the capillary tube is probably to avoid getting kinks. That's a very common failure mode for these things. Most of the waterbed heaters that I've owned over the last too many years have used those stupid bulbs and capillaries. I was really happy to get one that had a thermistor to put underneath the mattress and nice flexible wires instead of that damn bulb. As far as prying up tabs goes, you should get yourself one of the chiplifters from Wiha. They are essentially a miniature crowbar with an end that's maybe 1/8 inch across and curved so that you get leverage to bend things up.

[@glenn1524]

the isolation provided by the sleeving is a fine tune for the system

[@billssolarpowerandgardenin1016]

Mostly they are insulated to avoid shorting on bare electrical and objects running into it rubbing a hole. Forgot to unplug a unit on a repair and got too close to the terminals inserting the capillary tube and pop! Off to see the wizard for another one.

[@obelixer9751]

Yes, it's purely for electrical insulation, the center screw is for calibration. It's just a run o the mill thermostat. High temperature regulators could "explode" at the moment you cut it like he just did.

[@AndrewGillard]

Ah! So that's what those things in my oven are! I've had to remove our oven from the fitted kitchen cabinet four times¹ in the past year to replace the mode selector switch and then one of the heating elements, and I saw these two metal tubes leading from the thermostat dials to each of the two ovens, so they were clearly for temperature sensing but, only being familiar with thermistors, thermocouples, PT100s, and similar *electronic* temperature sensors, I was expecting something like that (i.e. at least 2 wires), so only seeing a single metal tube totally confused me! ¹ Removing it twice per replaced item: once to get the details of the broken part that needed ordering, then later to actually replace it. The heating element was less than £10 from Amazon, so I was a bit doubtful about it, but it's been working fine for a few months already. Although with the amount of time it takes to replace the heating element on my oven, it'd *definitely* be better to buy the ~£30 version if this £10 part fails in short order!

[@zh84]

Since I was a child I have imagined that the thermostatic control in an oven works by means of a bimetallic strip. I am fascinated to learn that I was completely wrong and ovens use an entirely different principle.

[@snigwithasword1284]

Likewise I would have been dumbfounded! Good on you for knowing the value of your labor!

[@bluerizlagirl]

@@zh84 You don't need the amplifying effect of two different metals with the temperature difference between an oven and ambient. Now, the hob controls _do_ use a bi-metallic strip; only it is not actually sensing the temperature of the cooking ring, but a separate little heating element which just heats the bi-metallic strip. This and the ring are wired to come on together, so the rate at which energy is delivered to the food (i.e., the mean power output) is proportional to the mean power output of the thermostat's own little private heater, which you adjust with the knob. It's an example of a feed-forward control system.

[@zh84]

@@bluerizlagirl Interesting! I had no idea that's how it worked. Thank you. I took a lot of things to pieces in my childhood, but never a stove.

[@BRUXXUS]

Pretty "cool"! I'd never really thought about these before, but the engineering is really pretty elegant. I also really love the tiny metal accordion.

[@bigclivedotcom]

Just a few pounds/dollars on eBay if you want one for the bits.

[@darkmann12]

heh hey there bruxxus

[@BRUXXUS]

@@darkmann12 Howdy!

[@arty1799]

The tiny metal accordion is a bellows ( en.wikipedia.org/wiki/Metal_bellows ). The processes for making them are pretty cool. For long lived thermostats they can be made by hydroforming ( kzbin.info/www/bejne/iobEnmeJfceBgNk ) or electrodeposition ( kzbin.info/www/bejne/hYW1ZYaAh7uWedE ). The bellows in Clive's video were most likely hydroformed as they are much cheaper. Hats off to Clive for educating and entertaining us!

[@jkobain]

A couple of days ago I had to explain how thermostats like these work. I reckon I preformed not really bad, but now that Clive has emerged on topic, I can get back to the discussion again and demonstrate this video. Because it should help even more. Thank you, as always.

[@davida1hiwaaynet]

Hi Clive. I'm heavy into antique and vintage refrigeration equipment. The ones with the saturated vapor capillary tube are very common with the old fridges. They depend on the sensing tip of the tube to be cooler than the body and diaphragm of the switch. The vapor pressure of the working fluid is what really gives these their accuracy. I've made several videos of rebuilding these when the sensing line gets broken. Depending on the temperature range the control was designed to work at, they used different working fluids. Some of them used sulphur dioxide; methyl chloride, Freon-12, isobutane, or propane. When rebuilding the fridge thermostats, if you can determine the temperature it is supposed to switch it, you can apply gas pressure and determine what pressure triggers the switch. With that information, you can consult pressure-temperature charts and find a suitable refrigerant gas to use for a working fluid. One of the original manufacturers of the vapor type thermostats is Ranco company. They have been in it for decades and have published quite a lot of repair info in the past decades. Ranco are still around and still very high quality. I think the second one you had in this video was a Ranco knock-off. Many of the ones I've rebuilt recently ended up with butane being the correct gas. Back in the old days, they referred to the ones with the expanding fluid (like the first one you worked on) as "hydraulic" thermostats. The ones with saturated vapor were called "gas" or "vapor" thermostats. I've been wanting to study and learn to repair the "hydraulic" type of controls. There are few who repair them when the capillary tube gets broken. The secret (as you said) is in the thermal expansion coefficient of the working fluid. Here's an isobutane thermostat getting repaired: kzbin.info/www/bejne/jXnZaoiqbMyorac This one was originally methyl chloride, but I used 1,1,difluoroethane for it. It's almost like your second one you showed. In spite of being very similar, it's from back in the War of the Currents era in the States. Back when AC and DC were both competing technologies. Love the old stuff! Repair video: kzbin.info/www/bejne/fmi5gqypZsyDoM0 Thanks for the teardown video! I enjoyed it a lot. I hope you enjoy seeing my repair videos on these.

[@jmc1771]

You are spot on. Glad I read through and didn't repeat your comment.

[@jabroski69]

I do HVAC cold and hot side equipment repair you got yourself a sub good sir I love old equipment your living my dream homie I'll be there one day

[@davida1hiwaaynet]

@@jabroski69 Thank you, much appreciated!

[@joaoliduario]

The 1st time I dealt with one of these I thought that tubing was an encapsulation for the sensor(that I thought was a thermocouple, thermal transistor, etc). I opened the vial and, to my huge surprise, it came out an oily fluid. I washed my hand several times, because I didn't know if that could be poisonous. It turns out that the oven was 100% electro-mechanical. I remember taking some time to understand what was going on, but eventually came out with the conclusion(that was correct). I love these mechanisms... they are like puzzles.

[@ferrumignis]

_"was 100% electro-mechanical"_ Quickly converted to 100% dysfunctional 😁

[@tomhoehler3284]

The little "diaphragm" on the second unit is typically called a bellows.

[@K2teknik.]

The two with a vial are for sensing the room/box temperature, the last one is made to sense on the evaporator, and it matters a lot to get the right type for your application.

[@lathiat]

This was very helpful i was trying to figure this out after watching HVACR videos. A quick google was failing me but explained in the first 30 seconds. Sometimes the capillary connects to the system or to a bulb but either way the point of the capillary is to transfer the pressure with a small impact of the volume of the capillary.

[@TechTheGamer]

On the freezer thermostats I’ve seen that are mounted inside, they have all been filled with some type of refrigerant. Interesting to see one that is just oil. I believe you can tell the difference by not only the diaphragm but also the expansion bulb. The oil ones appear to have a much larger surface area for the expansion bulb whereas the ones with a refrigerant have extremely small, almost non-existent expansion bulbs. Probably due to the thermal sensitivity of refrigerants.

[@Taristin]

Look up the MSDS (material data safety sheet) for a Honeywell aqua stat. They list their capillary liquid as a mix of Mineral oil, lithium hydrostearate, Zinc Alkyldithiophosphate, and a few other aluminum components, and stearates. I looked it up on a job one day when I had gotten it all over me. Wanted to know if it was carcinogenic. They say it isnt.

[@tncorgi92]

Similar thing happened to me with a barrel of MEK. Isn't it great that everything can be found online? Whereas before shops had to keep volumes of paper.

[@tin2001]

They say it's not carcinogenic, but I bet when they sell it in California it has that famous cancer sticker on it 😂

[@RicoElectrico]

@@tin2001 Known in the state of Cancer to cause California ;]

[@soranuareane]

"Panty rings for extra security while horse-riding." There's so much to unpack in that little sentence.

[@BRUXXUS]

😂🤣😂

[@jindivik321]

i laughed out loud at this :D taking the piss out of the panty liner adverts but delivers it so deadpan like. love it :D

[@jamesplotkin4674]

Today's "liberated" female rides "free bleeding" as well as runners. Eww...

[@bluephreakr]

wings*

[@alunthomas3789]

I always wondered how these thermostats worked. Thanks for the video it was very informative.

[@deepblueskyshine]

Over the years I've changed lots of these - ovens, water boilers, water and oil filled heaters. I've never seen any fault different from spring relaxation of the switch mechanism caused by faulty contacts overheating it. Expanding sensor-actuator part might be a dark sciense for a lazy person, but the spring mechanism of the switch is a real engineering voodoo. Changing heater thermostats in my very old apartment, however, became a very difficult task - they were made in England, but apparently no more so getting new one is a quest of walking through all spare parts shops without websites in criptic parts of the town.

[@jlucasound]

His name is "Nowis", Clive!! You wrote it right on the side of the device!! ;-)

[@theskett]

I was also troubled by this, for the first minute or two :-)

[@peregrine1970]

"so you can't RAM IT RIGHT PAST THE END STOP." Gig-gi-ty.

[@CanadairCL44]

Shades of Quagmire LOL !

[@sootikins]

"Ouch!" said her cervix.

[@mickpress6718]

movement of the drum has to be slight as it is magnified by the armature due to its closeness to the pivot

[@davidv1289]

The capillary only thermostat is designed to be mounted inside the conditioned space (frig or freezer) and as you said uses the tube and bellows for temperature sensing. The screw and attached spring assembly make up the span adjustment - the difference in temperature between on and off - and the other screw is the calibration adjustment.

[@pleasecho2]

These "hydraulic" thermostats had to be calbrated for use in high altitudes. Also if you can find an old Cutler-Hammer thermostat, they not only have a method of calibration but separate screws for adjusting the cut-in and cut-out.

[@jaymartinson3236]

The last thermostat you took apart is indeed for a freezer. My Arctic King 5 cubit foot chest freezer has the exact same thermostat. It's so cheaply made that over time, the small vibrations of the compressor cause the set screw to turn, which causes the freezer to to stop getting as cold after a few years. Most people just throw the whole unit away, but it can be fixed by simply adjusting the set screw on the side. Mine is especially bad and has had to be adjusted twice in 3 years. Meanwhile, the freezer on my fridge from the 1970s has been holding 0°F for 40 years and hasn't missed a beat. It's sad how cheaply things are made now.

[@SimonPain]

I've learned a new excuse: "I didn't drop it, those are calibration dents"

[@JuanJose-tn8yd]

Nop, thoses are "speed holes" xD

[@WineScrounger]

Dent tuning waveguide is a thing. Kinda alarming the first time you see it done but it’s very effective.

[@andreasu.3546]

I'll try this next time retuning a rental car.

[@dariandelparte9720]

its common for the capillary type to be embedded in the evaporator coil to sense to temperatures of the coil itself, another reason why the temperature range is so low. the contacts that stay closed all the time are for your evaporator fan motor to run 100% of the time, the other contacts switch your compressor and condenser fan on. from what i've been told by industry, most of these liquids are a refrigerant of sorts.

[@amorphuc]

Fascinating! Thanks Big Clive! It's kind of wild that so little movement will control our appliances. The gas one seemed pretty simple until you delved into its inner workings. Such seemingly simple little pressed metal bits and springs creating something of fairly complex actuation. I think those engineers have earned their keep!

[@commonlawsouthafrica]

what a lively thread, i just had fridge/freezer re-gassed, after that it was running continuously, fridge down to 0.6C° and ice build up on suction pipe at compressor; figure thermostat must be faulty, replaced it with identical new WDF28C-L-EX, no change, it either still runs too cold, or after turning one of these small screws, the compressor cuts out, but doesn't come back on; also, my thermostat has got 3 tiny screws, one on the front (knob side) and sunk in, another on the side, which made the compressor cut out when turning and a third even smaller and sunk in brass screw on the backside; i can't find any information what the actual functions of all 3 screws are, any ideas here ? thank you

[@why_do_you_want_to_know]

The third type (without bulb but with big bellow diaphram) is used in 5 gallon bottled water dispensers which usually have two thermostats. One for chilling side of dispenser and second for heating side so you can get hot water for tea/coffee or cold water for drinking. The capillary tube of each is wrapped around respective small insulated heated or chilled water holding tanks. Temperature setting shaft for chilled water tank is either inside dispenser case (for factory adjustment only) or extends outside but without any knob or dial scale for user adjustment.

[@BrendanPerkins]

Those big bulbous knobs would look good on my steam punk electric guitar. 🎸 Especially going up to 110, it'll make it louder. 😉

[@RedwoodRhiadra]

If you put on the -30 to 30 knob, does the guitar start sucking sounds from the air, making it quieter as you play?

[@BrendanPerkins]

@@RedwoodRhiadra That's got to be worth a try. 😂 I need a new guitar amp, my old one definitely sucks!

[@davidrichardson376]

The volume of the bellows/diaphram is much larger than the capiliary and is therefore gas operated, since the diaphram movement is large enough to operate a microswitch. The refrigerant in the system is presurised and boils at a certain pressure (set by the setpoint dial spring pressire on the diaphram) thus increasing it's volume and operating the microswitch.

[@danstone_0001]

Thermodynamics I love it! Fan speed, Condenser temperature, evaporator temperature. And room ambient temperature all play a role

[@ILikeStyx]

Ugh... I've a similar kind of thermostat in my HVAC heat pump, line voltage mechanical thermostat... its temperature range fluctuates so it's terrible to manage, getting it replaced with a digital thermostat this spring :)

[@stridermt2k]

A delightful exploration! In our scrap area at work I'm always finding rolls of copper capillary tubing that have been cut. Always wanting to find a use other than a magnetic loop antenna. LOL

[@bigclivedotcom]

You could wrap it round a heating element to make a simple smoke machine. Not sure how long it would last though.

[@stridermt2k]

@@bigclivedotcom that just sounds like me getting in trouble at work... I'll get right on it! LOL

[@cyberhornthedragon]

i worked in a valve manufacturer several years ago an i had the job of putting thermal switches on the valves with electronics an comtrolers valve positioners 'most' of the thermostats i had to work with it was a highly refined mineral oil as it wont freeze an has a high boiling vapor point

[@PhilipLeitch]

Big Clive for the save! Helped me confirm my freezer thermostat was working perfectly

[@graemezimmer604]

I think the "gas" would be something like Freon, and it's transition from liquid to gas depends on the temperature and pressure (the state transition giving much more decisive action). Plus the two adjustments are to set the amount of Hysteresis as well as the Temperature.

[@lefty5349]

The last thermostat you showed is a typical fridge variety, it is nearly always mounted inside the fridge, at the back right next to the evaporator. So the whole of the unit is essentially in the conditioned space.

[@zh84]

16:11 "This has little wings that fold round, little pantie-wings that fold round, for extra security when you're horse-riding." And those who watched ITV in the 90s may understand why this makes me think immediately of "UUUAAAAARRGH, BAAHDYFORM!"

[@nixxonnor]

LOL :D

[@minkymootwo]

I wonder if those little wings stick to hemp panties?

[@WineScrounger]

I haven’t heard it in years and you made it play back perfectly in my head. God punish you.

[@jindivik321]

There's a Mr.Bean episode where he can't sleep. He puts the TV on and there's a chess tournament, he's about to nod off and the Bodyform ad comes on and scares the crap out of him :D

[@richiep7812]

Still in common use all of this. The square one is a simmer stat used for catering trolleys. Some say there temperature range on the side.

[@RedFathom]

the small tube one uses vapor. the liquid-vapor change doesn't need much contact area, and the pressure inside changes the temperature at which it condenses/evaporates.

[@stephenbrown5927]

It is a freezer stat the reason for the the extra terminal is it brings on a red warning light about 10 degrees above the set temperature so you can see there might be a problem. The capillary only need about 80mm in the cold area to work as the pressure will change even if only a small amount is cold area.

[@eDoc2020]

That makes sense. My family's old freezer has a neon on the front which has gotten disconnected sometime in the past several decades. A warning light makes more sense to me than a 'plugged-in' light.

[@ChrisD4335]

almost a half hour of big c pulling his knob, thats hot!!!

[@throttlebottle5906]

at 2:55 that type is common in many refrigeration uses, the other mistake is not winding the excess sense tube into a coil and making sure to place it away from the refrigerant tubing (suction or pressure) with will skew it greatly, especially in the sense of a deli display case (learned the hard way)

[@bigclivedotcom]

Likewise with a fat fryer when the tube touched the element.

[@phils4634]

Dead simple (and remarkably reliable) mechanism! Able to (reliably) switch decent current too, so an example of excellent (although nowadays decidedly "legacy") engineering. As you say, almost "everything" these days will be electronically controlled (pre-programmed PID controllers) which (though offering far closer control ranges) do seem to be far less reliable, despite "no moving parts inside".

[@k4be.]

I have disassembled multiple water heater thermostats years ago, and all of them contained ether, with Li-ion electrolyte smell and instant evaporation.

[@mendaliv]

The MSDS I found for one remote bulb thermostat said it contained toluene. A Honeywell datasheet for a different unit said the bulb fill could be toluene or silicone oil. These both appeared to be for HVAC applications.

[@tweed532]

Others have mentioned the last one used in fridges, 'Off and then numbers', no specific temperature setting. I like a cold, cold fridge and on mine, the two screws going into the springs I've tweaked before now to set the low and high temp it cycles at, making it narrower hysteresis band than stock. (Usual disclaimer in case yours wasn't like mine. 😉)

[@TheWhiteAfghan]

the 3rd contact is just a line jumper that sends 120v to board for the "fast cool" feature. All it does is bypass the thermostat and power the unit to start cooling when you hit the button

[@davejordan6922]

The last one with the coppery diaphragm is almost certainly out of a mini fridge. I had to replace one just the other day. it has the same diaphragm, three terminals, and the gray plastic section attached to the aluminum section. the form factor appears to be identical. although the guts are slightly different.

[@chrisw1462]

The two screws on the front are for calibration - they set the depth of the stem (the first thermostat).

[@nixxonnor]

You do it like Dave. You take it apaat... Awesome analysis of the thermostats at hand.

[@soupflood]

A single 555 or an op-amp can also be used to make a fridge thermostat (if you don't have a microcontroller based one). The only trouble is that a 3...5 minutes pause should be implemented between turn-on and turn-off.

[@Peter_S_]

That's why you use a 556.

[@soupflood]

@@Peter_S_ good point, Peter: use a 555 as timer for another 555

[@Peter_S_]

@@soupflood long delays with the 555 get a bit random, but that's tolerable for a compressor delay. I was recently looking at the oscillators of the Roland Jupiter-4 synthesizer who's arpeggiator was made famous by Duran Duran in Rio, and the oscillators actually use a 555 to trigger a reset of each oscillator period. What a great chip.

[@soupflood]

@@Peter_S_ i was still thinking about the one 555 delaying another 555, but that only works at power-up, not between each disconnect of the compressor after it reaches set temperature. I guess only 555 can't maintain a delay between compressor cycles too, for example to avoid premature turn-on if the door has been opened right after compressor shut down.

[@Peter_S_]

@@soupflood Hmmm.. As a digital nerd, my first thought is usually, "is it cheating to add a couple 4000 series chips?", but I don't think it's necessary here. I think if you use the first 555 as a comparator where the output provides a little hysteresis via a feedback resistor and the discharge pin is otherwise floating, and then use the output of that 1st timer to trigger the 2nd timer wired as a delay where the discharge pin on the first timer is actually used to discharge the cap on the 2nd timer and the 2nd timer's discharge pin is left floating, you can end up with a comparator with hysteresis that triggers an RC delay to finally start the compressor after a delay which is retriggered any time its called to start. Maybe the connections for the delay would be a resistor from 555-A pin 3 to 555-A pin 7 and 555-B pin 6 to the cap to ground. If I had a 556 handy I would breadboard it.

[@deathlydarkness]

Clive, I also see this style of thermostat in Boilers for coffee and other dispensing equipment.

[@bigclivedotcom]

Similar units.

[@barryjackson2351]

the freezer stat has 2 temps settings 1 is adjustable to switch at -15 if temp rises above this it will light a red neon or a buzzer the other is to compressor at -18 to -28

[@barryjackson2351]

the capillary is usually filled with refrigerant r22 or butane

[@bigclivedotcom]

This was an oil that lit when heated.

[@barryjackson2351]

@@bigclivedotcom the refigerant is under pressure with a minute bit of oil in

[@phils4634]

Might be a nice contrast to take apart one of those Chinese electronic thermostats (such as the ever-popular Willhay WH360, which seems to be everywhere on the "usual sites"!) They work pretty well, seem reliable enough (ours have lasted 10+ years with zero problems), and have enough added functionality to be of use in heating and cooling applications.

[@paulspaws1521]

While repairing appliances I noticed that when some of these are broken the contents of the probes sometimes ignite quite spectacularly when exposed to air, shame you didn't get one like that, I always found it amusing.

[@bigclivedotcom]

I lit the liquid one. It took a lot of heat, but then burned.

[@RedaReda-uk9lm]

I think that liquid is called a refrigerant it could be HFC example R134a. Thanks Sir

[@robbatley]

Commonly use toluene as the working fluid in most of the displacement type of thermostats.

[@johndododoe1411]

Many freezers have a fast freezing mode that runs the compressor continuously when freezing large amounts of fresh produce.

[@Peter_A1466]

You really got me shouting at my screen this time 😁 The gassy one might have been liquid within it's operating temperature range... And the more narrow the diaphragm, the bigger the travel for a given expansion of the medium used.

[@ferrumignis]

That type tends to use a small amount of a low boiling point refrigerant such as butane or freon in the bulb,which is gaseous under the relatively low pressure within the capillary. Since the temperature coefficient of expansion is much higher for a gas, but the force that can be applied it much lower (since gas is compressible) the bellows is constructed to deal with much more movement than the liquid based thermostat.

[@Peter_A1466]

@@ferrumignis I was thinking it would be most effective during it's transition fase...

[@TheJunky228]

TIL! I guess I assumed they worked off of electronics like using a thermistor or something to that effect. This makes more sense for a low-cost thermostat, like in a mini-fridge

[@eDoc2020]

I presume units with a digital temperature control use thermistors. I've only had 'old-fashioned' fridges with the temperature knob and you can hear these click even when unplugged. If you notice conventional refrigerators also have a motorized defrost timer. If the compressor is off but you hear a slight ticking coming from the thermostat area chances are it's defrosting.

[@pizzablender]

That bellows / diaphragm is so shallow and flat because it needs a small volume. After all, the themostat measures the average temperature of all the liquid. Having too much volume in the themostat unit makes it sensitive to the temperature of the environment.

[@carlosmolina3850]

we use silicon oil or glycerine as transmission liquid in diaphragm seals :)

[@billssolarpowerandgardenin1016]

The smaller shorter capillary tubes thermostat requires the capillary tube be inserted in traditionally an evaporator coil. A tube is installed in the coil to receive capillary tube. Edit: this one would be considered Medium Temp.

[@27dcx]

I think some of those cap tubes contain refrigerant, which variety I am not sure. The one you cut open that had nothing in it probably had a whisp of refrigerant.

[@penfold7800]

Maybe the first one has hydraulic silicon oil in it. I'm guessing it might be more likely that it works by heat affecting the pressure of a vacuum in the vial that squeezes the silicon oil down the capillary tube

[@heavydiesel]

Remember the old Teddington QR stats, they used sulphur dioxide as the sensing gas!

[@WineScrounger]

Just to be extra manly? Seems reasonable. I’ll take three.

[@heavydiesel]

@@WineScrounger probably 40 years ago now i think about it, used to help dad out at work on school holidays!

[@WineScrounger]

@@heavydiesel cool stuff. I can’t see sulphur dioxide passing the sniff test these days. Although I do wonder if some thermostats would rely on a phase change for temperature sensing. Maybe that’s the reason?

[@briangeneral9505]

I think the first one is for fridges mostly neofrost fridges and the 2nd one is for Windows ac because I've tried to use the 2nd one in some neofrost fridges and failed to perform accordingly.

[@TheRockeye007]

the second one is for a heating and cooling window unit.

[@Roy_Tellason]

I've seen things of this sort also used to regulate the temperature of an oven...

[@turbomar6667]

At 12:30 I wanted to know what the liquid tasted like😉 BTW, not sure if it's still the case but fridge doors were held shut by magnet strips inside the door seal

[@eDoc2020]

That's still how they work. My understanding is before they added the magnets you needed to manually latch the door shut.

[@willi-fg2dh]

reminds me of the sensor that shuts off the gas to the pilot light on older gas appliances (the water heater and furnace in my folks house, for instance) those were almost bulbless.

[@bigclivedotcom]

That was possibly a thermocouple. Generating just enough current to keep a magnetic valve engaged.

[@willi-fg2dh]

@@bigclivedotcom thanks, sounds about right. there was an odd setup in the controls, tried to replace the old mercury tilt-switch thermostat with a programmable thermostat . . . the system put such a low voltage on the line that the new t-stat couldn't switch it without so much loss that the furnace would never come on . . . i think i measured it at less than 1v. might have worked with a relay type t-stat but all i had was a transistor(?) switched one. the system would switch on and off even when the power was out . . . i wonder if the installer used a thermocouple source for power?

[@eDoc2020]

@@willi-fg2dh Yes, I believe those systems usually use a thermopile (several thermocouples in series). It's called a 'millivolt' control system.

[@echothehusky]

Aww you didn't set fire to the oil! It burns really well. The last 2 I cut open the oil smelled a lot like standard 28 second heating oil, and it burned quite nicely once warmed. (well it burned with a lot of smoke anyway...)

[@pear7777]

???No Fire??? Downvote!!..jk

[@Peter_S_]

The couple I've found data on were filled with oil and fungicide/corrosion inhibitor. Google tributyleneglycol biborate which is an endocrine disruptor and stay away from the smoke or skin contamination. I really wouldn't burn or even mess with it.

[@Aengus42]

@@Peter_S_ "endocrine disruptor - skin contamination" You mean Clive's gonna grow boobs now?

[@Peter_S_]

@@Aengus42 No, they would have to be moobs I think. They used the same chemical in hydraulic fluid for the giant missile elevators I used to occasionally repair so I looked into how bad it was to be coated init when changing seals or replacing components. It's an EPA registered pesticide and biocide so I wouldn't recommend it as a drink mixer.

[@Aengus42]

@@Peter_S_ I wonder what qualities it had over normal, bog standard hydraulic fluid for it to be worth the risk! Especially seeing as it must've been in fairly large quantities. I worked a hydraulic weed barge on UK canals and that stuff you could bathe in! (I'm kidding, but it wasn't hazardous.)

[@Mtematiks]

Hi Clive, The small thermostat is full with ether!

[@RolandElliottFirstG]

That air one is a newer type , i haven't seen them before, they may be less acurate than the arsnic filled capilary type.

[@bigclivedotcom]

Not so sure about arsenic. The liquid one had an oil in it.

[@RolandElliottFirstG]

@@bigclivedotcom Arsnic looks feels and tastes like oil. I am joking/

[@licensetodrive9930]

Clive, have you seen the new battery powered 2x LED COB lightswitch from Poundland? It has a slide potentiometer connected to minimal circutry to change the brightness, it has an integrated switch mechanism to cut power. Quite well designed actually, but disappointing the COB LEDs are smaller and have 8 diodes each on a single board instead of 10 diodes on individual boards like the previous one (I bought them for the components)

[@bigclivedotcom]

I'll keep a look out for that. The current will probably be giving the potentiometer a hard time.

[@licensetodrive9930]

@@bigclivedotcom That's what I thought until I looked at the SMD components on the underside of the circuitboard, 0ohm resistor (used as a jumper), 10ohm resistor, 470ohm resistor and a transistor. You'd look at the circuit and instantly figure out what's happening, to me it appears the slide potentiometer is adjusting the voltage going into the base of the transistor to change LED brightness. Should be a good teardown video when (if) you get one.

[@Gold63Beast]

14:30 I’m still working on my carefulness lol. Always have little scrapes, cuts on my fingers from tinkering.

[@crash3ksa]

13:53 That thermostat is usually found in window type air conditioners the 3 legs are usually to control heating and cooling functions

[@JonasWilms]

That's a standard european fridge thermostat the live connection is just for the lightbulb.

[@crash3ksa]

@@JonasWilms interesting

[@redlock4004]

The Opening Things Up Channel.

[@lovotcore6946]

I would have used propane, and filled the vial half full, the pressure in the tube is directly proportional to the temp of the propane, as long as there's liquid in the tube it doesn't matter how full it is, it works the same.

[@TheUserid82]

Not air filled as that you would have too many variables so it would be filled with a pure gas like nitrogen or a mixed gas where you have a known expansion rate.

[@phonotical]

In the stream tonight, could you maybe explain how a mercury rectifier actually makes current dc? (and he never did)

[@666Bern666]

You seem to have got off lightly. I used to be a refrigeration engineer and to the best of my knowledge the gas in the phile is ammonia. I've certainly broken some over the years and can confirm you do not want to be breaking them next to your face! :-) Maybe they no longer use ammonia, I dont know but they certainly did in the past.

[@richard180961]

Very interesting indeed.. Clive, you may have just saved my bacon here. re, the WDF18 type thermostat. Mine appears very similar a WDF27 variety. from a small LEC fridge freezer. It appeared to be faulty, so could not resist carefully taking it apart. I have only removed the bellows and switch, by bending the "panty wings" but now unable to get the bellows back in, as they are very extended, and have found that a lot of pressure is required to push them down again, " Unlike yours" I am concidering getting some freezer spray, inorder to make the bellows retract, so as I can get them back in again. But previously having bought a new one which I was told would be compatible, does not fix the problem. The switch is indeed a strange arrangement: C: Compressor H: Live L: to the light switch. Between C & H there is intially continuity, but as one pushed the centre pin down it becomes o/c until it clicks, where once again continuity is restored. Some very useful information here in video. Thank you.

[@pavlosm8827]

Could it be that C is for compressor, H is for heater element (not installed in cheap refrigerator models) and L is for Line?

[@danielmusat597]

Hi, As far as I know, the liquid inside the capillary tube is paraffin. Cheers!

[@alphabuilders]

Also the listing says wdf18, because if that's the part that's failed in your device is a wdf18, then guess what.. Sellers are just box shifters. RS components offer a spec and host the pdfs for there parts, but guess what, the want a multiple of the price you paid, even in bulk, orders are often on a 14 day lead and postage is extra. The common terminals are... one for power in and the the other is loop out, usually for a power light indicator, to show the item is on. This spade connection is a convenient, cheap way of doing it. The part is performing double duty as a connector using a connection standard already used in the devices construction, and allows for easy field repairs/tests.

[@TheWhiteAfghan]

That part number is for a GE fridge thermostat

[@eDoc2020]

That could explain why the third thermostat looks remarkably like the one in my GE fridge. But AFAIK mine doesn't have a third contact.

[@TheWhiteAfghan]

@@eDoc2020 the 3rd contact is just a line jumper that sends 120v to board for the "fast cool" feature. All it does is bypass the thermostat and power the unit to start cooling when you hit the button

[@eDoc2020]

@@TheWhiteAfghan AH, I've never had a fridge with that feature. For that matter I haven't had a fridge with a circuit board, only conventional thermostats and defrost times directly connected on a harness.

[@TheWhiteAfghan]

@@eDoc2020 those were the good ol' days.. im an appliance tech 😁

[@scorchio70]

Love all your content Clive, please don't ever stop, I could watch and listen to you explain just about anything. (Loved your hot dog video, watched it from start to finish, were they friends , family or both?)

[@bren106]

Quite a lot of domestic freezers have that bulb in the cabinet, so the mystery oil would have to be food safe. Your fingers aren't likely to rot off from exposure to it.

[@nathanwallace7072]

I cut one of those open once and the liquid bust into smoke and flames as it dripped on to my tile floor.🥰

[@MordecaiV]

The "sleeve" is almost certainly more for physical protection than insulation.

[@Uncle-Duncan-Shack]

I replaced one of those cap tube with gas in type thermostats once, it was new but the owner of the fridge said: That wire was too long when we installed the new thermostat so we cut it shorter..................................