Re: Three pin refrigerator thermostat?

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Davej wrote...
Quoted text here. Click to load it

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


--  
 Thanks,
    - Win

Re: Three pin refrigerator thermostat?
On Monday, February 11, 2019 at 4:54:50 PM UTC-6, Winfield Hill wrote:
Quoted text here. Click to load it

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.

Re: Three pin refrigerator thermostat?
Davej wrote...
Quoted text here. Click to load it

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


--  
 Thanks,
    - Win

Re: Three pin refrigerator thermostat?
On Monday, February 11, 2019 at 9:41:50 PM UTC-5, Winfield Hill wrote:
Quoted text here. Click to load it

This type usually has the L coming in one pin to a mechanically activated S
PST, it is open in the detent OFF position on the knob, and closed when the
 knob is moved out of the detent. The throw of the input switch splits to t
he poles on two additional SPST which are temperature activated by the capi
llary tube pressure pushing on an internal diaphragm. One of the SPST has a
 high current rating for the compressor circuit. The other SPST could be us
ed to drive a low wattage RUN indicator or it could have a slightly higher  
activation temperature to drive an over-temperature alarm. For the price sh
own, the second internal SPST most likely drives a RUN indicator. They use  
two pins separated by the the two SPST to keep that compressor overvoltage/
 kickback voltage off the indicator circuit and its wiring. The compressor  
circuit usually requires significantly higher voltage rating wiring. There  
could be other reason, like eliminating a sneak circuit through the compres
sor winding in some other oddball application.  
The product is mis-advertized as "universal" which it clearly is not. Unive
rsal refers to the mechanics of mounting the thermostat, and real universal
 products contain an assortment of mounting brackets, or a pre-scored brack
et that can be broken down to size, as well as contact adapters. This produ
ct has none of that.

Re: Three pin refrigerator thermostat?
Those things were designed by engineers. A piece of wire costs pennies, PEN
NIES I TELLYA !

there is not a piece of wire going to the box unless the box needs it. If t
hey want switched power that comes on with the compressor they already have
 it. If they want constant power as long as the main switch is on they alre
ady have it.  

When a heater thermally coupled to the temperature sensor comes ON it makes
 the cooling device (compressor) run longer, thus over(under)shooting the s
et point. It continues beyond the set point and then when the compressor go
es off so does the heater thermally coupled to the...you know.  

For that little off grid project we went to a store and talked the (night)  
manager into letting us put an interrupter between a new fridge and power t
o measure the amperage. On a small fridge, supposedly high enough efficienc
y to be sold new we found that it pulls 17.8 amps to start and only about 0
.8 amps to run.  

It is for a short time but those times add up. So how many times do you wan
t to pay for that 17.8 amps ? Actually it will be more if it tries to come  
on too soon because of backpressure in the system. (the Freon)

Now compare that to a heating system. Your furnace. If a gas furnace when i
t starts it fires up first and then turns on the blower when the plenum/hea
t exchanger temperature gets to a set point. Older units were not quite as  
bad at wasting electricity during the time in between. Plus the blower dela
y was set by conditions. Still a bunch of your heat went up the chimney. In
 a newer furnace it starts the induction fan, then the igniter, and then th
e gas. Then the blower is on a timer, not turned on by a set point. During  
THAT time, an older furnace is ore efficient, but once really going the new
er one will waste less heat.  

I know people who are EXPERTS in this shit and especially energy management
. They work at a major university in town here. One I had to teach electron
ics or he would have flunked out of school. But he knows his shit now and g
ets to play with some really neato toys at work. They control everything, a
ir pressure on each room and all that. (labs with dangerous shit must be ke
pt at a negative air pressure so when they open the door they don't get it  
into the hall, the doors will slam if not equipped with closer things, and  
everybody is warned not to get their fingers in the wrong place. Some of th
em are highly respected and paid researchers so some of them might have som
e common sense)

When we started tossing down beers on the weekends we did not talk about ce
lebrities or even broads much, that is considered a little bit personal. (e
xcept for when his Wife was trying to kill him) We talked about shit like t
his as well as other areas of technology. Cars, audio, you name it, but no  
lame shit. That is true of almost everyone I know/knew. He brought me probl
ems from work sometimes when he had trouble, I made him buy beer. Now he is
 really good and never needs anything from me. I buy most of my own beer.

Re: Three pin refrigerator thermostat?
Quoted text here. Click to load it

I neglected to say that in a heating system the anticipator, heater in the  
thermostat that is, runs when the heating system is OFF. Cooling it runs wh
en ON. They don't have a "cold" source. A Peltier device would never work,  
you only got milliamps at 24 VAC.

Re: Three pin refrigerator thermostat?
On Tuesday, February 12, 2019 at 4:54:28 PM UTC-5, snipped-for-privacy@gmail.com wrote:
Quoted text here. Click to load it

That's false.  It actually only runs when the system is running, it's just a
resistor in series with the thermostat switch.



Quoted text here. Click to load it


I've never seen a thermostat for a cooling system that has an
anticipator.  It really would have to be a cold source,
to cool the thermostat in anticipation of the cooling left in the system.
Otherwise all it's going to do is heat the thermostat all the time when
the system is off and cause it to turn on a bit earlier.  It will have
little to no effect on anticipating how much cold remains in the system
when the compressor shuts off. AFAIK, they achieve hysteresis in other
ways.  Modern digital thermostats, which most people have today, do the anticipator function through software anyway.

  

Re: Three pin refrigerator thermostat?
On Tuesday, February 12, 2019 at 4:49:54 PM UTC-5, snipped-for-privacy@gmail.com wrote:
Quoted text here. Click to load it
ENNIES I TELLYA !
I'll have to check the numbers, but I think 1" of bus wire costs us the  
same as a 1% 1/4W MF TH resistor.  (We buy many resistors, not so much  
bus wire.)  

George H.  
(who hasn't been following along with all of the thread.)
Quoted text here. Click to load it
 they want switched power that comes on with the compressor they already ha
ve it. If they want constant power as long as the main switch is on they al
ready have it.  
Quoted text here. Click to load it
es the cooling device (compressor) run longer, thus over(under)shooting the
 set point. It continues beyond the set point and then when the compressor  
goes off so does the heater thermally coupled to the...you know.  
Quoted text here. Click to load it
) manager into letting us put an interrupter between a new fridge and power
 to measure the amperage. On a small fridge, supposedly high enough efficie
ncy to be sold new we found that it pulls 17.8 amps to start and only about
 0.8 amps to run.  
Quoted text here. Click to load it
ant to pay for that 17.8 amps ? Actually it will be more if it tries to com
e on too soon because of backpressure in the system. (the Freon)
Quoted text here. Click to load it
 it starts it fires up first and then turns on the blower when the plenum/h
eat exchanger temperature gets to a set point. Older units were not quite a
s bad at wasting electricity during the time in between. Plus the blower de
lay was set by conditions. Still a bunch of your heat went up the chimney.  
In a newer furnace it starts the induction fan, then the igniter, and then  
the gas. Then the blower is on a timer, not turned on by a set point. Durin
g THAT time, an older furnace is ore efficient, but once really going the n
ewer one will waste less heat.  
Quoted text here. Click to load it
nt. They work at a major university in town here. One I had to teach electr
onics or he would have flunked out of school. But he knows his shit now and
 gets to play with some really neato toys at work. They control everything,
 air pressure on each room and all that. (labs with dangerous shit must be  
kept at a negative air pressure so when they open the door they don't get i
t into the hall, the doors will slam if not equipped with closer things, an
d everybody is warned not to get their fingers in the wrong place. Some of  
them are highly respected and paid researchers so some of them might have s
ome common sense)
Quoted text here. Click to load it
celebrities or even broads much, that is considered a little bit personal.  
(except for when his Wife was trying to kill him) We talked about shit like
 this as well as other areas of technology. Cars, audio, you name it, but n
o lame shit. That is true of almost everyone I know/knew. He brought me pro
blems from work sometimes when he had trouble, I made him buy beer. Now he  
is really good and never needs anything from me. I buy most of my own beer.


Re: Three pin refrigerator thermostat?
On Tuesday, February 12, 2019 at 4:49:54 PM UTC-5, snipped-for-privacy@gmail.com wrote:
Quoted text here. Click to load it
ENNIES I TELLYA !
Quoted text here. Click to load it
 they want switched power that comes on with the compressor they already ha
ve it. If they want constant power as long as the main switch is on they al
ready have it.  
Quoted text here. Click to load it
es the cooling device (compressor) run longer, thus over(under)shooting the
 set point. It continues beyond the set point and then when the compressor  
goes off so does the heater thermally coupled to the...you know.  
Quoted text here. Click to load it
) manager into letting us put an interrupter between a new fridge and power
 to measure the amperage. On a small fridge, supposedly high enough efficie
ncy to be sold new we found that it pulls 17.8 amps to start and only about
 0.8 amps to run.  
Quoted text here. Click to load it
ant to pay for that 17.8 amps ? Actually it will be more if it tries to com
e on too soon because of backpressure in the system. (the Freon)
Quoted text here. Click to load it
 it starts it fires up first and then turns on the blower when the plenum/h
eat exchanger temperature gets to a set point. Older units were not quite a
s bad at wasting electricity during the time in between.  

Instead they just wasted furnace heat, by not utilizing it sooner, so more
of it went up the chimney during the first minute or so.  But overall, this
is just a nit.



Plus the blower delay was set by conditions. Still a bunch of your heat wen
t up the chimney. In a newer furnace it starts the induction fan, then the  
igniter, and then the gas. Then the blower is on a timer, not turned on by  
a set point. During THAT time, an older furnace is ore efficient, but once  
really going the newer one will waste less heat.  

No evidence in the above that one is really more efficient than another.
And it's all of about a minute that you're talking about, a nit.



Re: Three pin refrigerator thermostat?
Quoted text here. Click to load it

nah... it'd work.

think of the resistor as providing an elevated ambient temperature in
the thermostat.  turning the resistor off would have the same effect
as indroducing a cold source of the same magnitude as the resistor's
heat.

I don't know how much after cool there is once the heat-pump shuts off.
so this probably isn't going to be real useful.

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

Site Timeline