help finding switch please

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  #1  
Old 01-07-14, 10:41 AM
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help finding switch please

The "micro switch" needs to be replaced on an electric in-wall space heater. It is of the design similar to this one in the link provided below (although not a Honeywell brand). The differences, however, is that I need a 22A (not 15A as the one in the link), and there is no middle terminal (the "always open" terminal) on my switch needing replacement either. Instead, on mine it is just flat where that middle terminal is located on the switch in the link. My switch needing replacement has only the two terminals on each end, one marked "common" and the other marked "always closed". I've searched rather extensively online trying to come up with a matching replacement but without success.
Info on my switch is on one side it says 22A 125,250, or 277 VAC, 1/4 HP 125 VAC, 1/2 HP 250 VAC , 22A 250V ~ T85 5E4
And on the other side it says WM-1R369-AR4 Mexico (the apparent part number).
Any guidance/advice to help me locate/acquire the proper replacement switch would be appreciated! Thanks.
Honeywell Micro Switch BZ 2R21 A2 Snap Action SPDT Pin Plunger Actuator 15A 250V | eBay
 
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  #2  
Old 01-07-14, 11:10 AM
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Micro Switch

Check the Honeywell WM-1R369-AR2. Can't tell for sure but they look close to what you have. This is a single-pole NC like you described although later in your post you say SPDT. I think this may be one that would work.

Link:
Product Page
 
  #3  
Old 01-07-14, 11:27 AM
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Thanks, that one may well work; however, I can't tell you for sure (being unfamiliar with the difference) whether the one I need should be SPNC or SPDT. Like I mentioned, the one I need to replace has no middle terminal... thanks for any further comment.
 
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Old 01-07-14, 01:39 PM
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With a multimeter set to ohms check for continuity when the pin is not pressed. If you get continuity it is NC (normally closed). If you get infinity it is NO (normally open). Those two terms can apply to single throw switch regardless of number of poles. SPDT refers to the number of poles and throws not if NO or NC however a double throw switch can be use as a single throw NO or NC by using only one side.*

*The switch has two sides and a center terminal. Power is fed to the center terminal. Power goes to one side when not depressed. By using that side for load it is NC. If you use the side that is not connected to the center when the pin isn't depressed it is NO.
 
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Old 01-07-14, 01:58 PM
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I should make a correction to my initial post here where I wrote "My switch needing replacement has only the two terminals on each end, one marked "common" and the other marked "always closed".

That was incorrect; instead the sentence should have said My switch needing replacement has only the two terminals on each end, one marked "common" and the other marked "norm closed".

Also, there is a cardboard jacket that was fitted over my switch before I removed it from the heater. On it it says 22 Amp single pole.
 
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Old 01-07-14, 09:00 PM
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So if I am understanding correctly, I should be able to just go ahead and replace my switch with the one bahtah suggested (Honeywell WM-1R369-AR2), and not worry that there's a middle terminal on the replacement switch (just don't use it), and just be sure to connect the correct wire to the terminal marked as common and also the correct wire to terminal marked as "norm closed" on the replacement switch, and it should work fine?
 
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Old 01-08-14, 01:01 AM
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Yep, just use the NC and COM terminals and ignore the NO terminal. Which wire goes to which terminal isn't even important.
 
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Old 01-08-14, 08:18 AM
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Okay. Is there any reason this one shouldn't also work for me as a replacement as well? HONEYWELL S&C - BM-1R-A2 - MICRO SWITCH, PIN PLUNGER, SPDT 22A 250V: Amazon.com: Industrial & Scientific

The switch (linked above) is apparently a BM series, whereas the original switch and the one suggested by bahtah are WM series. However, in this Honeywell line guide I don't see any info about WM series, so am wondering about that now. http://sensing.honeywell.com/honeywe...e=WM-1R369-AR2

And yet now I've come across this, which should be a definite replacement, per the part number which matches the original. Honeywell Sensing and Control Product Search.
 

Last edited by sgull; 01-08-14 at 09:20 AM.
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Old 01-08-14, 02:27 PM
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Honeywell, who owns the Microswitch brand, makes about a gazillion different models with many different characteristics including style, mounting, current carrying capacity, actuating pressures and probably others that I am forgetting.
 
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Old 01-08-14, 02:42 PM
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I ended up checking with Grainger (because we have an account with them, and no local sources otherwise) to source me out the Honeywell Microswitch number WM-1R369-AR4. Couldn't find it on ebay or Amazon. Probably end up costing me on the higher end for it; awaiting a quote. Thanks to all for the help/input.
 
  #11  
Old 01-08-14, 03:28 PM
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Yeah, Grainger is the place. Their prices have risen astronomically (in my opinion) as they have drastically increased their inventory but they usually can get what you need in a timely manner. I used to buy from them on a regular basis but not so much these days. I think the last thing I bought was some 250 volt slo-blow fuses for my washing machine, no one else had them and ordering them would have taken at least a week. The Grainger nearest my home didn't stock them (didn't seem to stock anything I wanted and may have closed recently) but the one that did have them was only about fifteen miles away.
 
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Old 01-08-14, 04:15 PM
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Yeah well there is no actual Grainger store nearby my location but I shop/order from their catalog/online and so of course also end up having to pay freight on top of anything I get from them. They can usually "source-out" stuff that's not in their catalog or what they normally stock otherwise. Call em tell em what you're looking for (with part numbers and other pertinent info), and they get back to you within a day or two with a price quote, usually comparatively rather spendy on most everything, but at least usually available in a reasonably timely manner.
 
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Old 01-13-14, 10:10 AM
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Update: Finally got a quote back from Grainger on that switch. They can only obtain/resell them in packages of five, so if I purchased through Grainger I'd be stuck having to buy five when I need only one. Plus they'd be charging over 26 bucks per switch and also would be charging me over 26 bucks for UPS ground shipping so the total ends up being 157 bucks! Forget that.
So my other option in mind instead is just to get this one from Amazon, which will cost a total of 26 bucks plus change including the shipping: HONEYWELL S&C - BM-1R-A2 - MICRO SWITCH, PIN PLUNGER, SPDT 22A 250V: Amazon.com: Industrial & Scientific That switch should work fine, eh?
 

Last edited by sgull; 01-13-14 at 12:38 PM.
  #14  
Old 01-14-14, 12:28 AM
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Since you have never stated exactly what this switch controls or exactly how it is actuated it is utterly impossible to say with any certainty that the switch in the Amazon link will or won't work for you. Perhaps a few pictures of the switch in place and a description of what it controls would help.

Most "microswitches" have some kind of lever actuator that depresses the plunger for switch actuation. It is for this reason that there are so many different switches, with different actuating pressures and travels along with different mountings.
 
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Old 01-14-14, 09:40 AM
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The switch I need to replace controls the heat output of a wall heater, and is actuated when the knob is turned on the front of the heater. The specs for the actual part (same part number) I'll be replacing are as shown in this link (specs tab): Product Page
The specs for the switch I'm considering getting from Amazon to use as a replacement are shown in this link (specs tab): Product Page
Here's some (rather poor quality, sorry) pictures; one showing the switch in its mounting bracket and one showing it out of it, and another showing how the switch/bracket is installed into the heater:





 
  #16  
Old 01-15-14, 12:39 AM
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So, if I understand correctly this Microswitch is a component of the thermostat that controls the heater. If the new switch has an actuation pressure different than the original switch or an actuation range different from the original switch it may not work as well as the original switch. It could be more sensitive or less sensitive to temperature changes in the ambient area. Ideally you would replace the entire thermostat sub-assembly.

The replacement switch may work just fine. Unless this heater is located in an area where aesthetics are important I would have probably installed a completely separate electric heat wall thermostat.
 
  #17  
Old 01-15-14, 09:36 AM
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Yes this switch is a component of the thermostat that controls the heater.

If the new switch has an actuation pressure different than the original switch or an actuation range different from the original switch it may not work as well as the original switch. It could be more sensitive or less sensitive to temperature changes in the ambient area.
I'm uncertain whether any of the following specs have anything to do with the actuation range or pressure. I assume some if not all probably do:
The new switch has an "operating force" spec of 1,95 N to 2,78 N [7.0 oz to 10.0 oz] max., whereas the original switch has an operating force spec of 3,06 N to 4,73 N [11.0 oz to 17.0 oz] max.
The new switch has a "release force" spec of 1,11 N [4.0 oz] min., whereas there is no such spec shown for the original switch.
The new switch shows a "pretravel" spec of 0,38 mm [0.015 in] max., whereas there is no such spec shown for the original switch.
The new switch has a "differential travel" spec of 0,013 mm [0.0005 in] max., whereas the original switch has a differential travel of 0,025 mm [0.001 in] max.

Ideally you would replace the entire thermostat sub-assembly.
Not sure what all that would be, or whether I could obtain such, especially at a cost less than just replacing the entire heater.

The replacement switch may work just fine.
Or, may not, apparently?

Unless this heater is located in an area where aesthetics are important I would have probably installed a completely separate electric heat wall thermostat.
The heater is in a tiny entryway room. Aesthetics are not particularly important, although to go to the trouble of installing a separate wall thermostat would be impractical in this particular situation.
 
  #18  
Old 01-16-14, 03:45 AM
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I don't know what to tell you. The switch you have selected may work just fine, or it may work but not have the same sensitivity as the original or it may not work at all. The heater manufacturer would be the source for the exact thermostat/switch module but they may charge a pretty penny for it. Or you could perhaps cobble up a similar thermostat from a different brand of heater. Or possibly mount the wall-type thermostat on the cover of the heater.

One thing I'm pretty sure of is that any thermostat is going to cost more than $20 so the replacement switch might be worth trying. It has been at least ten years since I bought an internal thermostat for an electric unit heater (Q-Mark brand from Grainger) and if I remember correctly that little beast was in excess of thirty dollars. I had two similar heaters and rather than spending that outrageous amount I simply mounted a standard electric heat wall thermostat on the back of the heater. Those heaters are still going where at least two (of four) of the internal thermostats have crapped out.
 
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