Any Electricians out there?

[SeaCat]

Okay I ran across a switch today that I haven't seen before.

http://i269.photobucket.com/albums/jj79/Seacat_01/ACPanel2.jpg

This one is obviously broken.

I know that it is a heat activated switch. (Inside the base is a metal cup that heats up when current is applied. When the cup heats up it causes a Bi-Metal disk to warp and activate a switch.)

Oh I should add that the base is 110V while the top part controlled by the switch is 220V.

If you have seen one of these what is it called? (I need to replace this one obviously.)

Cat

 

[Handley_Page]

Okay I ran across a switch today that I haven't seen before.

http://i269.photobucket.com/albums/jj79/Seacat_01/ACPanel2.jpg

This one is obviously broken.

I know that it is a heat activated switch. (Inside the base is a metal cup that heats up when current is applied. When the cup heats up it causes a Bi-Metal disk to warp and activate a switch.)

Oh I should add that the base is 110V while the top part controlled by the switch is 220V.

If you have seen one of these what is it called? (I need to replace this one obviously.)

Cat

Usually it's a thermostatic switch.

 

[unregistered]

 

[OzoneRed]

See if your AC manufacturer has a website. See if they sell replacement parts for your model. Even if you don't want to pay the outrageous price they'll probably charge, you should be able to get a part name and part number.

 

[Weird Harold]

I've found that identifying mystery components is often possible by googling the part number printed on them.

 

[SeaCat]

I've found that identifying mystery components is often possible by googling the part number printed on them.

I'll have to try that. Thanks.

(Now I have to reopen the cabinet to get to the switch so I can get the numbers off it.)

So far I haven't received an answer to my question but I have gotten some informative answers as well as a link to a good site with info on A/C systems.

My father, the Electronics Engineer liked the description of the switch and it's operation I sent to him. (He's never seen a switch quite like this one.) He asked a lot of detailed questions and wanted to know how I had figured them out. It seems most people, even engineers can't figure out things like this easily.

AS for this switch, well if I can't find a replacement easily then maybe I'll have to wire in a simpler electricly activated on off switch that will handle that voltage load.

Cat

 

[SeaCat]

See if your AC manufacturer has a website. See if they sell replacement parts for your model. Even if you don't want to pay the outrageous price they'll probably charge, you should be able to get a part name and part number.

The problem with that is this seems to be some kind of older generic system. I have found a wiring diagram on the inside of one panel but it has no info about the manufacturer. Nor does the details panel on the front of the system.

It's an older system, (20 years old) but it still works so I want to keep it that way.

Cat

 

[Jenny_Jackson]

Cat, I had the same problem with my furnace. I went to --> http://www.hvacpartsoutlet.com/ and gave them the manufactur's name and model of the appliance and the numbers from the obsolete part. They sent me a replacement. ($36.00 including shipping)

 

[JAMESBJOHNSON]

There arent THAT many devices to switch on air conditioning units. I assume you have a self contained trailer unit that connects to duct under the trailer. I assume you have a breaker box inside the trailer and a switch box outside.

220 volt lines usually come as two distinct 110 volt wires paired up. The single 110 volt line is likely for the compressor fan or the blower that pushes air into the ducts. Compressors normally use 220 volts.

The line to the thermostat should be DC (direct current).

Now if all these wires run to the same place the switch is likely a common switch that operates compressor, blower, cooling fan, and thermostat. There is likely a simple transformer in the switch to convert AC to DC and drop the voltage from 110 to whatever the thermostat requires.

 

[jacks4u]

Cat,

Thermostatic, thermal cutoff, or just plain thermal switch. They are in all manner of devices, from coffee pots to A/C systems and everything in between. They are typically used to cut electricity in case of a thermal 'event'. some are manually resettable, some automatically reset, and some are 'one time', kind of like a thermal fuse. But you have it slightly wrong - the bi-metal part doesn't usually respond to applied current, but rather to the temperature of what it's fastened to, where the metal cup is contacting. In this case, the A/C - it's likely attached to the 'fire box' or location where there are heater elements, either gas or electric.

In your picture, is this one device, with the red and brown wires going to it? or is it 'Blowed up", with the blue(x2), red(large) and black(x2) wires as well? Usually they are a simple device with only two wires, and a single 'break/make' connection, that's controlled by a bi-metal srtip. But I wouldn't be surprised to see something more elaborate.

The part number on the device, as Weird Harold suggests will be most informative. I also google part numbers on a regular basis. the Manufacturer will also be a helpful bit of info. I usually search for these things with "mfg partno" as in "National ne555"

The real tricky part is if there is either no part # or no info on the web. Sometimes people at appliance parts houses will recognize parts. In my area, the place I go is "Appliance parts co." Keep your photo, you may need it to connect a new one. You might also take some more, from different angles and closer up.or do as I often do, get a pencil and paper, draw the device, the connected wires, including size and color, and even mark similar colored wires to differentiate between them.




Jacks

 

[Handley_Page]

If you have a decent voltmeter, you might like to check some voltage readings first

 

[SeaCat]

Okay here's some more info.

Here's the original picture for reference:

http://i269.photobucket.com/albums/jj79/Seacat_01/ACPanel2.jpg

I dug out my fancy assed digital Multi-Meter to do some testing as I worked today. (It's a pain in the ass to use because the readings have a nasty habit of bouncing around.)

Now this is one unit that has exploded or come apart.

The base is attached to the panel. The two wires attached to this are the orange and purple wires. These wires run to the Thermostat and carry 24V AC. (No not DC AC. I double checked that.) The current running through these are what heat and cause the Bi-Metal plate to warp and open or close the switch.

The switch is enclosed in the section that is hanging from the multiple wires. The two black wires coming in from the right are both 110VAC Lines coming from the Breakers.

The front Black Wire goes through the switch to a double connector, (Blue and Red Wires) which goes to another switch and then to the Heater Coils. The back Black Wire goes through the second switch to the other Blue Wire which goes to the Blower Motor.

Now here is a picture taken after I removed the switch from the Unit.

http://i269.photobucket.com/albums/jj79/Seacat_01/ACPanel3.jpg

Here it is taken apart so you can see the two sections as well as the cup and the Bi-Metal Disk.

http://i269.photobucket.com/albums/jj79/Seacat_01/ACPanel4.jpg

Because the switch didn't work when it was in pieces I decided that it didn't really matter what I did. I pulled it out of the A/C and after cleaning it up a bit and making sure I had all the parts and knew how they went together I sat down with it and a bottle of Super Glue. (Gorilla Brand thank you very much.)

Yep I worked carefully and glued it back together.

Son of a gun if that didn't work. The switch works as it's supposed to.

Now I have to figure out why the Heater Coils aren't heating up. Oh well at least I don't need the heat right now so I have time to trouble shoot this system.

Oh and the A/C side of the system works just fine now that I've replaced the Electric Motor.

Cat

 

[JAMESBJOHNSON]

JACKS said

"Thermostatic, thermal cutoff, or just plain thermal switch. They are in all manner of devices, from coffee pots to A/C systems and everything in between. They are typically used to cut electricity in case of a thermal 'event'. some are manually resettable, some automatically reset, and some are 'one time', kind of like a thermal fuse. But you have it slightly wrong - the bi-metal part doesn't usually respond to applied current, but rather to the temperature of what it's fastened to, where the metal cup is contacting. In this case, the A/C - it's likely attached to the 'fire box' or location where there are heater elements, either gas or electric."

God invented circuit breakers and fuses to handle excessively hot wires when electrical devices draw too much current.

I think CATs confused about the thermostat; youre correct, thermostats operate by the difference in the conductivity/resistance of different metals inside the thermostat. If he's measuring AC current on a thermostat something is amiss. All the thermostat does is open and close a circuit to a solenoid or switch that opens or closes switches/ circuits to the compressor and the blower.

CAT in Vietnam we used to saw plastic switch cases apart to get at broken electrical contacts; we soldered new metal onto the old and glued the case back together.

Heater coils burn out, what can I tell you. Find someone who sells-services trailer air conditioners, and they likely have used parts they'll let you have off of junk units.

 

[unregistered]

 

[SwipeCard]

If you connect a copper wire to a aluminum wire your are asking
for trouble.

You have to buy paste to apply to both connectors, then use a
"butt" connector to put them together.

 

[SeaCat]

JACKS said

"Thermostatic, thermal cutoff, or just plain thermal switch. They are in all manner of devices, from coffee pots to A/C systems and everything in between. They are typically used to cut electricity in case of a thermal 'event'. some are manually resettable, some automatically reset, and some are 'one time', kind of like a thermal fuse. But you have it slightly wrong - the bi-metal part doesn't usually respond to applied current, but rather to the temperature of what it's fastened to, where the metal cup is contacting. In this case, the A/C - it's likely attached to the 'fire box' or location where there are heater elements, either gas or electric."

God invented circuit breakers and fuses to handle excessively hot wires when electrical devices draw too much current.

I think CATs confused about the thermostat; youre correct, thermostats operate by the difference in the conductivity/resistance of different metals inside the thermostat. If he's measuring AC current on a thermostat something is amiss. All the thermostat does is open and close a circuit to a solenoid or switch that opens or closes switches/ circuits to the compressor and the blower.

CAT in Vietnam we used to saw plastic switch cases apart to get at broken electrical contacts; we soldered new metal onto the old and glued the case back together.

Heater coils burn out, what can I tell you. Find someone who sells-services trailer air conditioners, and they likely have used parts they'll let you have off of junk units.

OKay, let me try to explain this once again.

In post #12 there are three pictures. The top picture shows the switching assembly as it was when I found it, broken and in two parts but with all wiring intact.

The second picture shows what it's supposed to look like while the third picture shows the assembly in it's component part.

Now in the third picture the base is on the top left. To the top right is the top section of the assembly where you can see the two puch rods. Below these sections are the cup and the Bi-Metal Disk.

The Bi-Metal Disk sits in the cup in a convex position so it pushes against the rods holding open the switches in the top section. The cup sits in the bottom of the bottom section against two leads which allow current to flow through the cup.

Now here is how this system works.

The thermostat inside the trailer is set at 70°F. If and when the temperature inside the trailer drops below 70° a switch inside the thermostat closes allowing current to flow into a very basic circuit. This current, (24 VAC) flows down the purple wire to the base of the unit. (Reference picture one) It flows through the cup into the Orange Wire and completes the circuit to the Thermostat.

This 24VAc current flowing through the cup heats the Bi-Metal Disk inside to causing it to warp into a concave shape. This pulls the disk away from the push rods allowing the switches inside the assembly to close.

Closing these switches allows the current, (110VAC) to flow from the Black wires on the left of the original picture through the switches to the Blue and Red Wires. The Blue and Red Wires run either through a Thermal Switch to the Heater Coils or to the Blower Motor.

When the temperature inside the trailer rises above the set point of 70°F the switch in the Thermostat opens. This stops the current from flowing to the base of the assembly which means the cup is no longer being heated. As the cup cools so does the Bi-Metal Disk. When it has cooled a bit it warps back to it's original shape of Convex which presses against the rods which opens the switches in the upper section of the assembly. This stops the flow of the current into the Heater Coils and the Blower Motor.

James, I have rebuilt motors and all kinds of switches. I have rewired radios and fixed things that would make your eyes bulge. This is the first time however I have run across a switch like this. It's kind of a neat way to do this kind of switching.

AS for the heater coils I'll have to dig into them now that I have the switch fixed.

Cat

 

[SeaCat]

Yahoo, I finally found out what this switch is.

It's called a Heat Sequencer. It's for timing the turning off and on of the Heater Coils and the Blower.

Thanks for the tip on Googling it Weird Harold. It turned out that Googling the Part Number didn't work but some of the other info printed on it did the trick. (The Timing Sequence to be exact.)

Cat

 

[JAMESBJOHNSON]

CAT

It makes no sense to me. Why would heat coils and blower require a temp sensitive switch when their operation is controlled by a thermostat inside the dwelling? If the coils or blower pull too much current the circuit breakers pop to stop them from operating. On 2nd thought maybe this heat sequensor is the thermostat, and the little box inside the house is a pacifer. I wonder if the real temp sensing device is in the return duct at the evaporator intake.

I went thru a military technical school, certified in airconditioning-refrigeration later on, and hold an advanced FCC license. So I know the theory. But I also know that designers do weird shit.

42 years ago the military sent me thru a school to learn electronics, electricity, hydraulics, pneumatics, refrigeration, gas-diesel-turbine engines, and lotsa other stuff like transmissions. And I know for a fact I cant do a tune-up on my car today cuz of all the nifty gizmo's cars require in 2010.

Okay, I see what the heat sequencer does. It staggers the activation of the heating coils to prevent excessive current draw at start-up. One coil lights up, then another, and so forth. And the 24VAC is correct. Kiss my ass. Its a surge protector. Manufacturers must be using smaller gauge wire these days.

 

[TxRad]

CAT

It makes no sense to me. Why would heat coils and blower require a temp sensitive switch when their operation is controlled by a thermostat inside the dwelling? If the coils or blower pull too much current the circuit breakers pop to stop them from operating. On 2nd thought maybe this heat sequensor is the thermostat, and the little box inside the house is a pacifer. I wonder if the real temp sensing device is in the return duct at the evaporator intake.

I went thru a military technical school, certified in airconditioning-refrigeration later on, and hold an advanced FCC license. So I know the theory. But I also know that designers do weird shit.

42 years ago the military sent me thru a school to learn electronics, electricity, hydraulics, pneumatics, refrigeration, gas-diesel-turbine engines, and lotsa other stuff like transmissions. And I know for a fact I cant do a tune-up on my car today cuz of all the nifty gizmo's cars require in 2010.

Okay, I see what the heat sequencer does. It staggers the activation of the heating coils to prevent excessive current draw at start-up. One coil lights up, then another, and so forth. And the 24VAC is correct. Kiss my ass. Its a surge protector. Manufacturers must be using smaller gauge wire these days.

Actually you are close but no cigar. This sequencer allows the temp to come up and cool down before turning the blower on and off. This way you have less cold air blowing around and it allows the heating elements to cool before turning the fan off.

Heating coils are set in parallel circuits so all the wires are the same size to each set of coils. They usually all come on at once unless you have a two stage unit. The size of the wire feeding these are set by "code" for the amp rating by the state. Most codes for Amperage ratings to wire sizes ain't changed in 30 to 50 years.

 

[JAMESBJOHNSON]

TEX

I dont know, I repeated what I read about heat sequencors for petroleum and electric furnaces.

I was curious why you'd need such a gadget on a trailer unit, but I know that manufacturers try to get away using smaller gauge wires or aluminum or whatever's cheap. I replaced a ground fault circuit interrupter outside outlet and discovered that my copper wiring is too large to connect to the new device. I'm guessing the building code changed.

 

[TxRad]

TEX

I dont know, I repeated what I read about heat sequencors for petroleum and electric furnaces.

I was curious why you'd need such a gadget on a trailer unit, but I know that manufacturers try to get away using smaller gauge wires or aluminum or whatever's cheap. I replaced a ground fault circuit interrupter outside outlet and discovered that my copper wiring is too large to connect to the new device. I'm guessing the building code changed.

The gadget is used for the same purpose no matter what the unit is installed in, house or trailer, it doesn't matter. in fact most mobile home systems are better built because of the moving of the unit and strict inspections.

The sequencer allows the temp of the heat to come up before starting the fan. The heat is felt quicker in the room. On shut down, it keeps the heating elements from over heating by shutting it off and allowing it to cool before the fan shuts off.

Manufactures are held to the same codes as the contractor that builds the house. The only time you see the whatever is cheap crap is when you buy off brand cheap crap.

As for your over sized copper wire, it was more likely to be a contractor putting in bigger wire for outside loads, which could have included electric lawn mowers, weed eaters, or a multitude of power tools when the structure was built. You also have to take into account how far from the main box this plug is and how many plugs were/are on the circuit. The circuit might even have been used for something else before it was a plug. I took out an old above ground pool when i moved where I live now. I converted the box where it tied into the house to an efi outside plug. The wire is overkill to say the least.

 

[SeaCat]

Well first the good news.

I called around a bit today to find where I could buy one of these sequencers. Thankfully the first place I called, (Grainger) not only had one but had several of them in stock. They gave me the part numbers and told me to check their website to find just the one I wanted. I did this and found it within minutes, along with the price. ($18.95)

Me being me I kept calling around to other places. Lowes and Home Depot don't carry them. (Too bad they're closer.) Three of the places that advertise in the phone book for selling parts to D.I.Y.'ers said they did have them in stock.

Their prices ranged from $40.00-$60.00 per unit. When I commented on the price the usual reply was that this was a highly specialized switch and that it was very delicate. It had to be handled just right. All three of these places then went into hard sell mode to have one of their techs come out and install the switch, which meant being charged for a service call as well as for time and labor. This would add a minimum of another $100.00 to the bill.

I let them talk and talk some more until they finally got to the point where they ask when they should schedule me for the repair work. That was when I asked them what they thought about the fact I had found the exact same switch they were trying to sell me for $18.95 and could easily have it installed in my unit in less than half an hour. All three hung up on me. (Now what did I expect right?)

Now for the even better news. With our weather being warm and humid, (It's currently a lovely 76° out with a muggy humidity of right around 85%.) the trailer has grown fairly warm and more than a bit damp. I decided that this was a perfect time to test out the A/C that I have finished repairing. (I fixed the A/C and am now working on the Heater section.)

I made sure the unit was energized then went to the Thermostat. It was reading 80°F in side so I set the temperature for 75°F. I also put a thermometer on the largest of the floor vents to see what happened.

The unit kicked on nice and quiet and just kept on running like it should. Within a couple of minutes the air coming out of the floor vent was reading 55°F and stayed there. It took all of 20 minutes for the system to drop the temperature the five degrees and cycle off just as it should. I'm quite happy with that result.

Tomorrow I'll go down and get that new sequencer and go back to working on the heater section. I may not need it often but seeing as it's there I want to have it up and running. Besides I'm sure it would be cheaper to heat this place using that than it is heating the place with my electric Space Heaters that I use now.

Cat

 

[Weird Harold]

I may not need it often but seeing as it's there I want to have it up and running. Besides I'm sure it would be cheaper to heat this place using that than it is heating the place with my electric Space Heaters that I use now.

I'm not sure that you will see any savings by using the central heat. The technology level of that sequencer suggests that it's a long way from "Energy Star Compliant." If your space heaters have thermostatic controls, and are less than 15 years old, they're probably more efficient.

I'd expect a relatively modern HVAC system to use solid state components for that kind of control function.