KB Electronics 8811006 Solid State Variable Speed AC Electric Motor Control, 2.5 Max amp, 115V, KBWC-13K

Works so far. I was able to adjust it down to having it almost not be able to run the exhaust fan. Sadly the fan makes a lot of noise (seems angry) when it's barely running so I adjusted it to run at 50% at the lowest. I notice other commenters remarking that they can't get it to go low enough, make sure the Amperage of the version you buy fits the application. I got the 2.5 amp for something that will at most take 1 amp. So it worked pretty well. Documentation is meant for electricians it seems, but I figured it out.

I'm a licensed engineer. I have an attic-style fan that I installed to circulate warm air from my utility room to the living spaces rather than letting that heat it escape through the attic by conduction. To accomplish this, I set the fan up with a thermostat control to turn on above 90F, which keeps the utility room pleasantly warm and dry while also re-circulating the excess heat. The problem was that the fan was way too fast and too loud in the adjacent living spaces when it kicked on. I needed something to slow down the fan, which was a low wattage AC fan with a permanent capacitor across the line (little round guy on the power cord going to the motor). You can't use a dimer switch for this sort of application because it will burn up, and many fan controllers intended for ceiling fans won't work either because they have fixed detents for replicating industry standard speeds at low/medium/high. By contrast, this controller uses a solid-state component called a Triac to give you much more precise continuous control over the fan speed. Using this controller, I was able to lower the fan to a much slower speed than the standardized fan controls, allowing me to get the right balance of comfortable warm airflow and quiet noise levels. When doing this, it is important to realize that AC motors can stall if the voltage is lowered too much, and that they will burn up in place if they stall with power on. These motors need the airflow to keep themselves cool while running. This control has a fine adjustment for setting for the minimum fan speed, which prevents someone from accidentally stalling the motor with the knob alone. This minimum speed adjustment was essential for me to achieve the desired effect in my home while preventing the fan from lowering below stall speed. Overall, this controller allowed me to fine-tune my attic-style fan safely and make my home much more comfortable in the winter while saving me money on heating bills and reducing the heat level in my utility room.

UPDATE0 first one only lasted two hrs when I adjusted the stall screw it just sizzled. 2nd one screw adjustment works just fine, but now my motor has a small hun, not bad, but I can hear it. First one was dead quiet till the adjustment sizzled out, But I still recommend these. Now matter how good a product is, there are bound to be a few defects. First off I had people telling me I could not use this on a Holmes window fan. Well I am glad they were wrong and I was right. This little baby works perfect, no noise, no heat and looks good. I even checked my fan motor for an increase in temperature, guess what, nope. And no funny motor noises as with most other speed control switches on the market. Simple and easy wiring. No adjustments were needed on the speed screw stall adjustment. I think everyone I spoke with said I would only get a max down to 70% some said 50% speed. Well I can go as low as I want with no ill effects. Most importantly doing that with no noise or heat issues is a huge bonus. So now my entry level Holmes fan with this controller is better than their most expensive so called adjustable fan. Cant say enough good things about this controller. If your wondering should you get this or something else, just get it.

Bought this to use on my attic fan. Easy to install and works great

This review is for the KBWC-13K solid state speed control. I purchased this controller with intent of modifying it so the fan of my Magic Heat unit would run slower and be less noisy when the woodstove fire was producing less heat. The Magic Heat uses a simple (on/off) thermostat controlled 1/200 hp single speed shaded pole fan motor to circulate heat into the room. So my next step after receiving the KBWC-13K was to disassemble it to see what I was working with. The attached photo illustrates the few components that are inside. Overall the components, assembly and soldering are of very good quality. The only oddity is the small trimmer potentiometer (black circular part with blue center located in middle front of the picture) which is wedged up against the larger control knob potentiometer leads. There's no real problem here; just not a typical component mounting. I suspect the trimmer is located in this manner to prevent heavy handed screwdriver users from damaging the trimmer. Overall I am very pleased with the construction/quality of this product. There are three minor design “features” to keep in mind with this speed controller given it was originally developed back in the 1960's. Most users probably won't notice these; but should be aware of them. The first requires understanding that the two potentiometers are set up in parallel. The circuit triggers on whichever potentiometer is set to a lower resistance. So, if the trimmer is set so the motor has a high minimum speed, then there's very little usable speed adjustment range from the control knob and vice versa. The second is that the circuit has control setting hysteresis. This can be observed if you dial the speed of a motor down to a very slow steady rpm and then disconnect the power to the circuit (as happens with the thermostat switch of the Magic Heat). When power is reapplied, the fan may struggle to start, if it does at all. If there was no hysteresis, the fan would spin back up to the original slow rpm setting. The third is the circuit's asymmetrical triggering of the triac. This can sometimes be heard as a repetitive, very low volume, loud-soft, HUM-hum-HUM-hum sound. This noise is often louder when working with old, poorly mounted, or cheaply made motors. I can usually identify this sound when I'm in an adjacent room where the low frequency of this noise comes through over the fan airflow noise. There's a ten page Teccor Electronics application note AN1003 on the web that provides a more technical understanding of this type of speed control. The entire controller operates at AC line voltages so disassembly and modification should only be done by a person educated/trained in AC power circuits/electronics. Here I'm suggesting an alternative use for the KBWC-13K; not a detailed modification process with essential safety considerations. The KBWC-13K potentiometers are configured as two-terminal components (center terminal, the “wiper”, is connected to one of the end terminals). This means I can easily replace the trimmer potentiometer with a two terminal negative temperature coefficient (NTC) thermistor. With a suitable NTC in place of the trimmer, the motor rpm will hold a steady slow speed at room temperature and increase the motor rpm with increasing temperatures up to the full motor speed at some desired high temperature. The control knob potentiometer is now used like the original trimmer to increase the minimum motor speed if it happens to be too slow at the desired low temperature. Another similar modification back in the 1970's/1980's was using a photocell in place of the trimmer which makes the fan speed up with increasing light levels. Keep in mind that these are low cost, simplistic controllers; the performance can vary significantly from one installation to another. After the modified controller was connected into the Magic Heat circuit, I decided to measure the fan current consumption. While the shaded pole fan was performing very well with the controller from minimum to maximum speed; measurements showed the fan was only 10% efficient at full speed and only slightly better at reduced speeds. Shaded pole motors under 1/15-1/20 hp are known to have very low efficiency which is what prompted me to test the current consumption. A Permanent Split Capacitor (PSC) motor usually has about double the efficiency of a similar hp shaded pole motor. So I modified the Magic Heat to use a PSC motor. However, the PSC motor was surprisingly noisy and sluggish when starting at low speed settings. An on-line search revealed that for a PSC motor, only the main (“run”) winding should be controlled by a phase type speed controller while the auxiliary (“start”; one with the capacitor) winding should bypass the speed control so it always has full AC power. The common two wire installation of the speed control has it wired in series with the motor so the motors' run and start windings are in parallel and powered by the controller simultaneously. This alternate approach makes the motor a 3-wire configuration, eliminating use of the built-in on/off switch of the speed controller (which I wasn't using anyway), and requires a separate on/off power switch (Magic Heat thermostat covers that). Having full voltage on the start winding, regardless of the speed controller setting on the run winding, provides full power for motor starting at all speed control settings. This modification reduces the slow speed operating noise (to a point) and increases motor efficiency at reduced speeds. In my installation, the 3-wire PSC motor configuration operates at a full speed efficiency of 33% and increases to a high of 53% at the minimum speed. Again, this is a modification that should only be performed by an electrician. Final note. If plan on buying 3 or more controllers; find a seller that reduces the selling price for buying multiple units vs a flat rate per unit. Sellers that adjust the built-in shipping costs according to the weight of your purchase may save you some money for multiple units. The single unit pricing of this Amazon seller is reasonable for a one or two unit purchase.

This speed control installs as if it were a simple switch in the hot wire line, plus a ground. That makes it easy to install ... make certain the breaker is off and no AC is present. Cut or unfasten the hot line to the original switch (probably a pull chain ... I did this in the fan switch box) and run a two conductor plus ground cable to where you want the speed control. Install a heat resistant box (the control does get warm, not hot) Connect the two insulated cable wires to the two wires on the motor control and connect the bare ground. Splice the other ends into the original switch hot wire that you cut. Do this in a junction box. I was able to squeeze these "fan side" connections (including ground) into the existing box that holds the pull chain switch. I set the pull chain switch for "high" (it has high, low, off settings) and then I removed the chain since the speed control would now control on/off/and speed functions. To be as "correct" as possible ... Since the new cable going to the speed control now technically carries "Hot" to the control and then back to the fan motor, use a black magic marker to color the ends of the white wire black. That gives fair warning to others that both lines in the cable are hot. I mounted the speed control in a hallway from the garage into the house, just below the fan. I noticed that the speed control housing itself is a heat sink that sits out about a half inch from the wall, so I mounted the switch above shoulder high so that we would be less likely to bump into it. After setting the "lowest speed" adjustment so that the shutters would not flop closed, all works perfectly. My fan is a direct drive motor that pulls 5 amps and this particular speed control is rated for 8 amps. The control gets slightly warm to the touch when it has been running on low for a long time, but the heat sink dissipates the heat very well. If your fan has shutters, make certain to keep the low speed high enough so that the shutters don't start to close. If they do, it is progressive. The shutters close a bit; the fan pulls harder and slows a bit, and then the shutters close more. Eventually the shutters are almost completely closed and flopping. In that case the fan motor is working hard and getting no air movement so it could overheat .... NOT a good thing!

The control has a small adjustment screw on the side that you are supposed to tweak when you install. The screw allows you to set the lowest speed (which should not be so slow that the motor stalls). You can set a slow speed easily enough, but two problems crop up after installation: 1. The taper isn't smooth, meaning that (in may case, with a fireplace fan) there really isn't a "medium" speed. In other words, as you turn the control towards "low" the speed of the fan stays pretty much the same until you reach a certain point at which the speed drops to the previously mentioned lowest setting. Same deal in reverse, i.e., as you turn the dial toward "high," the fan runs slow until it jumps to full speed. 2. If you set the control low enough to be, well...low, then any additional draw put on the same circuit stalls the motor. In my case I turned on a light, so we aren't talking major draw. I tried changing the adjustment (putting more load on the circuit and then setting the "low" adjustment a bit higher), but I couldn't find a happy medium. If I set the adjustment high enough to not be bothered by a minor additional stress on the circuit, the "low" setting was almost the same as the "high" setting. So, with these limitations, this speed control is effectively an on/off switch, something I could have purchased locally for less than a buck.

Quick delivery, item works great just as described. It was helpful in lowering the noise level of a garage exhaust fan.