Ok test complete.....results Looking good.
First hooked Lasko 200 watt resistive heater to grid power and let it run for 5 minutes to heat up as much as it would.
Hottest temperature I was able to find was 251.5 degrees when hunting with my IR temperature gun aimed into faceplate.
I then hooked it to router speed controller and started out at max speed, and found nearly exactly the same 250F when hunting for the hot spot.
I then lowered dial to 9 and then hottest spot found was then 214f. The small internal fan spun the same speed, audibly, even at a speed of 5 of 10 on the RSC.. 5 of 10 yielded a 148F max temperature. Seeing it was effectively lowering temps I did not really test the complete range of temperature vs dial setting.
Move RSC and Heater to 800 watt MSW inverter, put clamp meter over (-) cable of MSW inverter.
On initial turn on amps spiked to ~24, then over the course of a minute settled to 16.82 amps.
When I dialed it down to 9.5 of 10 on the dial, amps dropped to ~13 amps, and after that amp draw seemed linear to dial setting. I tested it as low as 3 on the dial and it was taking about 2.5 amps and not putting out much heat at all. The Lasko's fan was still spinning the same speed according to my ear.
So I believe the RSC will work to throttle back the Crockpot further. I would use the high setting and throttle it back on the RSC rather than use low on the RSC though.
My electric motors do not like being on LOW speed, then have the RSC throttle them. They buzz and whine. Much better to put fan on High then throttle it on RSC even if the range from highest to lowest is effectively from 10 to 8.5 on the RSC dial.
NOt sure if the same would apply to resisitve heating elements, but whatever method the crock pot employs on Low vs hot to throttle heat, might not like the PWM of the RSC output.
But It works on MSW inverter, and it effectively throttles both Heat and Amp draw of my Lasko 200 watt heater, and should do the same to a crock pot that is not allowed to go low enough because lawyers and the Nanny state had to jump in and protect humanity from their own ignorance.
I have the exact RSC that I linked and it has been used a lot previous to today's test. it likely has over an hour of use on a MSW inverter when I would use an angle grinder and flap sander to foil wooden fins, So the MSW at least does not instantly kill the RSC. It has accumulated many dozens of hours using it since it powered that angle grinder powering fans belt sanders, angle grinders and my Buckethead vaccuum.
Do not the RSC does not work properly on the 120vac powertools that have a soft start feature.
The only possible issue I see as a possibility is that effectively lowering crock pot temperatures to just below bubbling levels, might require 9.75 of 10 on the dial, so some experimentation and a fine touch might be required to dial in the temperature desired.