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Three pin refrigerator thermostat?

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Davej
Guest

Mon Feb 11, 2019 7:45 pm   



Can anyone explain the internal circuit of a 3-pin refrigerator
thermostat such as a WDF-xx ? Thanks.


https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=3+pin+refrigerator+thermostat


Guest

Mon Feb 11, 2019 8:45 pm   



On Monday, February 11, 2019 at 1:36:28 PM UTC-5, Davej wrote:
Quote:
Can anyone explain the internal circuit of a 3-pin refrigerator
thermostat such as a WDF-xx ? Thanks.


https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=3+pin+refrigerator+thermostat


Is this your thermostat?

http://kacang.xyz/editor/

Rick C.

Winfield Hill
Guest

Tue Feb 12, 2019 12:45 am   



Davej wrote...
Quote:

Can anyone explain the internal circuit of a 3-pin
refrigerator thermostat such as a WDF-xx ? Thanks.


One reviewer said, " If I remember the third terminal
is a hot lead for the light on the front panel. "


--
Thanks,
- Win

Davej
Guest

Tue Feb 12, 2019 1:45 am   



On Monday, February 11, 2019 at 4:54:50 PM UTC-6, Winfield Hill wrote:
Quote:
Davej wrote...

Can anyone explain the internal circuit of a 3-pin
refrigerator thermostat such as a WDF-xx ? Thanks.

One reviewer said, " If I remember the third terminal
is a hot lead for the light on the front panel. "


One suggestion is that the action is SPDT however I don't
know what you would want to power only when the compressor
is off.

Winfield Hill
Guest

Tue Feb 12, 2019 3:45 am   



Davej wrote...
Quote:

On Monday, February 11, 2019 at 4:54:50 PM UTC-6, Winfield Hill wrote:
Davej wrote...

Can anyone explain the internal circuit of a 3-pin
refrigerator thermostat such as a WDF-xx ? Thanks.

One reviewer said, " If I remember the third terminal
is a hot lead for the light on the front panel. "

One suggestion is that the action is SPDT however I don't
know what you would want to power only when the compressor
is off.


It could be dual spst, with a common terminal. That
could be suitable for driving a separate ON indicator.


--
Thanks,
- Win

Jasen Betts
Guest

Tue Feb 12, 2019 5:45 am   



On 2019-02-11, Davej <galt_57_at_hotmail.com> wrote:
Quote:
Can anyone explain the internal circuit of a 3-pin refrigerator
thermostat such as a WDF-xx ? Thanks.


https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=3+pin+refrigerator+thermostat


could be on-(off) momentarty press-action to switch the interior light.

could be used in a manual or automatic defrost cycle



--
When I tried casting out nines I made a hash of it.


Guest

Tue Feb 12, 2019 6:45 am   



For the anticipator. For heating the anticipator an be in series, not for cooling.


Guest

Tue Feb 12, 2019 6:45 am   



I miswhatevered.

the anticipator is not in series so much on a heat thermostat. It heats while the system is active and doesn't when it does to give the feedback system some hysteresis.

For cooling it is a different story. The anticipator needs to be ON when the cooler is active to heat up the thermostat. Therefore it needs a common. When the thermostat is satisfied the anticipator is no longer active and the cycle will be longer.

Anticipators are used to keep the system from short cycling or restarting too much. With a pumped, latent heat (Freon) cooling system they can help prevent it from trying to start the compressor under backpressure. If not and it cycles too short the compressor will not start and it will trip the overload. If it tries to start and that rotor doesn't run it might pull 17 amps. Each time the overload trips its reliability is reduced. they are not made to work all the time, they are only a safety.

Bottom line is that an anticipator in a cooling thermostat runs while the system is cooling. It heats the thermostat at a precise level which lengthens the on cycle. When the cycle is done, thermostat is satisfied and turns off the compressor, the anticipator is shut off and the measured temperature then drops, but there is stored heat.

In heating, the anticipator can be just across the switch terminals. Not so for cooling, it needs a common.

I am not saying they all have it. Also if there is any electronics in it the other wire is to power that, or provide a common. A simple light does not need that and can be wired just as easily using another common in the unit..

Yes, I have overcomplicated this to the nth degree. Are we having fun yet ?


Guest

Tue Feb 12, 2019 6:45 am   



On Tuesday, February 12, 2019 at 12:13:08 AM UTC-5, jurb...@gmail.com wrote:
Quote:
I miswhatevered.

the anticipator is not in series so much on a heat thermostat. It heats while the system is active and doesn't when it does to give the feedback system some hysteresis.

For cooling it is a different story. The anticipator needs to be ON when the cooler is active to heat up the thermostat. Therefore it needs a common.. When the thermostat is satisfied the anticipator is no longer active and the cycle will be longer.

Anticipators are used to keep the system from short cycling or restarting too much. With a pumped, latent heat (Freon) cooling system they can help prevent it from trying to start the compressor under backpressure. If not and it cycles too short the compressor will not start and it will trip the overload. If it tries to start and that rotor doesn't run it might pull 17 amps. Each time the overload trips its reliability is reduced. they are not made to work all the time, they are only a safety.

Bottom line is that an anticipator in a cooling thermostat runs while the system is cooling. It heats the thermostat at a precise level which lengthens the on cycle. When the cycle is done, thermostat is satisfied and turns off the compressor, the anticipator is shut off and the measured temperature then drops, but there is stored heat.

In heating, the anticipator can be just across the switch terminals. Not so for cooling, it needs a common.

I am not saying they all have it. Also if there is any electronics in it the other wire is to power that, or provide a common. A simple light does not need that and can be wired just as easily using another common in the unit.

Yes, I have overcomplicated this to the nth degree. Are we having fun yet ?


I expect there is no point in this, but you seem to have the anticipator mixed up. You actually state two different things for the heating system.

"It heats while the system is active and doesn't when it does to give the feedback system some hysteresis."

This is correct, other than the hysteresis part. Then, here at the end you say,

"In heating, the anticipator can be just across the switch terminals."

This is wrong. If active when the contacts are open (meaning heat is off) it would delay turning on the heating system and cause the house to get colder than it should. The anticipator prevents the system from overshooting the set point. It is wired to heat the thermostat when the heat is running so the heat cuts off a bit early.. and allows the residual heat in the burner or coils to be used to warm the house to the desired temperature. The fan must be connected, not to the heat demand thermostat, but to a thermostat in the heating unit so it runs until the burner/coils cools off.

The same need is present for heat pumps as they hold residual heat in their coils, but they don't use a standard anticipator heating the thermostat. They just design the thermostat with an MCU that does the same thing in software. At least that's how mine works as it turns the fan on low to extract the residual heat and not blow cold air through the house.

I don't know that it works any differently when running on cooling. If a thermal anticipator were used for cooling, it would be used warm the thermostat when not running. Then when the AC is on and the anticipator is not warming the thermostat the cooling would cut off earlier and allow the house to be cooled by residual heat/cold in the coils to reach the final temperature.

Rick C.


Guest

Tue Feb 12, 2019 8:45 am   



On Tuesday, February 12, 2019 at 1:51:44 AM UTC-5, jurb...@gmail.com wrote:
Quote:
"This is wrong. If active when the contacts are open (meaning heat is off) it would delay turning on the heating system and cause the house to get colder than it should. "

That is EXACTLY what it does so the thing does not turn on and off every minute.

That is working properly.

It doesn't mean the room gets down to ten degrees below set point to come on, fuck no. It is actually a calibrated thing,l you used to adjust it with a screwdriver or something, it was actually a wire wound rheostat in the thermostat. I have adjusted them. For cooling they need to be wired to have the exact opposite effect on the thermostat's detected temperature. That creates the need for a neutral or common.

The anticipator STORES heat in the thermostat. It radiates it for a preset amount of time. that time is set, ideally, to match the conditions in the dwelling being heated.


This is what I expected. Rather than try to learn, you just argue about it citing your experience which you must be remembering incorrectly. Try googling it. You will find many references that explain the function of utilizing the residual heat in a furnace and preventing overshoot of temperature just as I described it. For that to work, the anticipator has to be wired to heat the thermostat while the heating system is running, ending the heat cycle early.

Some sites also talk about preventing the rapid fluctuations you describe, but none say the anticipator is wired to heat the thermostat when the thermostat has turned the furnace heat off.

Rick C.


Guest

Tue Feb 12, 2019 8:45 am   



>"This is wrong. If active when the contacts are open (meaning heat is off) it would delay turning on the heating system and cause the house to get colder than it should. "

That is EXACTLY what it does so the thing does not turn on and off every minute.

That is working properly.

It doesn't mean the room gets down to ten degrees below set point to come on, fuck no. It is actually a calibrated thing,l you used to adjust it with a screwdriver or something, it was actually a wire wound rheostat in the thermostat. I have adjusted them. For cooling they need to be wired to have the exact opposite effect on the thermostat's detected temperature. That creates the need for a neutral or common.

The anticipator STORES heat in the thermostat. It radiates it for a preset amount of time. that time is set, ideally, to match the conditions in the dwelling being heated.


Guest

Tue Feb 12, 2019 12:45 pm   



On Tuesday, 12 February 2019 11:32:38 UTC, jurb...@gmail.com wrote:
Quote:
"An anticipator reduces the hysteresis of bimetal stats..."

Where the fuck did you get that ? It does EXACTLY the opposite.


I don't recall, I've known it a long time. Here's a semirandom link on the topic:
https://hvacrschool.com/good-old-heat-anticipator/


NT


Guest

Tue Feb 12, 2019 12:45 pm   



>"An anticipator reduces the hysteresis of bimetal stats..."

Where the fuck did you get that ? It does EXACTLY the opposite.


Guest

Tue Feb 12, 2019 12:45 pm   



>"Rick C."

Not worth my time. I know what the fuck I am talking about. So much for that.


Guest

Tue Feb 12, 2019 12:45 pm   



On Tuesday, 12 February 2019 05:13:08 UTC, jurb...@gmail.com wrote:
Quote:
I miswhatevered.

the anticipator is not in series so much on a heat thermostat. It heats while the system is active and doesn't when it does to give the feedback system some hysteresis.

For cooling it is a different story. The anticipator needs to be ON when the cooler is active to heat up the thermostat. Therefore it needs a common.. When the thermostat is satisfied the anticipator is no longer active and the cycle will be longer.

Anticipators are used to keep the system from short cycling or restarting too much. With a pumped, latent heat (Freon) cooling system they can help prevent it from trying to start the compressor under backpressure. If not and it cycles too short the compressor will not start and it will trip the overload. If it tries to start and that rotor doesn't run it might pull 17 amps. Each time the overload trips its reliability is reduced. they are not made to work all the time, they are only a safety.

Bottom line is that an anticipator in a cooling thermostat runs while the system is cooling. It heats the thermostat at a precise level which lengthens the on cycle. When the cycle is done, thermostat is satisfied and turns off the compressor, the anticipator is shut off and the measured temperature then drops, but there is stored heat.

In heating, the anticipator can be just across the switch terminals. Not so for cooling, it needs a common.

I am not saying they all have it. Also if there is any electronics in it the other wire is to power that, or provide a common. A simple light does not need that and can be wired just as easily using another common in the unit.

Yes, I have overcomplicated this to the nth degree. Are we having fun yet ?


An anticipator reduces the hysteresis of bimetal stats, so this must be a damn-what-happened-I-never-saw-that-coming-er or maybe just a hysteresisiser..


NT

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