A look at how capillary thermostats work and how to use them.
Capillary thermostats are a simple electromechanical thermal switch that uses a very thin metal tube to sense temperature at another location, by using the thermal expansion/contraction of liquid or gas to activate an adjustable switch.
The search keywords for finding a wide range of units on eBay are:-
"refrigerator thermostat"
Note that there are quite a few similar looking versions and a massive price range for the same thing.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.

12 thoughts on “Inside a cheap ebay fridge freezer thermostat”
  1. Avataaar/Circle Created with python_avatars G F says:

    is it thinkable to replace a capillary thermostat with an electronic one ? how could you power it though ?

  2. Avataaar/Circle Created with python_avatars richard180961 says:

    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.

  3. Avataaar/Circle Created with python_avatars Azhar Farooq says:

    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.

  4. Avataaar/Circle Created with python_avatars Roy Tellason says:

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

  5. Avataaar/Circle Created with python_avatars Somanathan says:

    You are practical as well as theoretical, very good sir

  6. Avataaar/Circle Created with python_avatars LEXICOGRAFFER says:

    Great job….showing how NOT to go about disassembly where the goal is to understand how thing functions and how it may be re-assembled. Having one foot in a childish approach to something like this really wastes a viewer;s time.

  7. Avataaar/Circle Created with python_avatars bpanther says:

    👋👋👋👋👋 for the clickety click discovery of the century 😝

  8. Avataaar/Circle Created with python_avatars bpanther says:

    Panties wit wings or rather sanipads wit wings while horsing around…or like me, while cycling long distance !!!

  9. Avataaar/Circle Created with python_avatars bpanther says:

    Havnt rd commnts much but if uv nt lookd up alrdy…it's PROPYLENE GLYCOL 😍

  10. Avataaar/Circle Created with python_avatars Nathan Wallace says:

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

  11. Avataaar/Circle Created with python_avatars Philip Leitch says:

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

  12. Avataaar/Circle Created with python_avatars Dave Fredrock says:

    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!

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