Low Cost Vacuum Rheostat Replacement
Nilfisk rheostats are expensive and temperamental. When they inevitably stop working your options usually are a multi hundred dollar official manufacturer’s replacement part or a new, cheaper variable speed vacuum with less control.
The following method is one that I’ve used a few times to successfully replace a dead rheostat for less than $25. It’s a little bit fiddly, but I think well worth it for the money saved. Please note that this is not my area of expertise. This method is one I gleaned from reading various amazon reviews and is in no way expert advice. Links at the bottom of this post. Please be careful.
The first thing is to purchase a third party rheostat. I’ve used this one with success. I found this option by searching for “fan speed controller” and choosing one that looked like an old Nilfisk rheostat, but other models will likely work as well. This version lacks a long power cord and a mounting bracket.
Next you’ll want to remove your current (dead) rheostat from the vacuum and its mounting bracket. Keep the bracket and reattach it to the vacuum. Save the cord that connects the rheostat to the vacuum.
If you aren’t replacing a dead rheostat, but are installing one for the first time you’ll need to order a connecting cord. I believe a NEMA C 13 is what will work, but I have not verified this. You’ll also need to install some sort of mounting system to your vacuum.
When you get your new rheostat, I recommend plugging it in and testing the range of suction with your vacuum cleaner. You will likely find that it is not nearly low enough for conservation work. To fix this:
Unplug the rheostat from the vacuum and the power (important!), then unscrew the back plate. Be aware that it will not come all the way off.
Locate the potentiometer (pot) that controls the speed. You will see a small circle with a slot that can be turned with a small flat head screwdriver.
Turn it about 1/8 of a turn clockwise. Then close up the back plate.
Plug in the rheostat to the vacuum and test the range of suction. It should now go considerably lower.
If you want to refine your speed further (very likely) repeat the process making smaller adjustments. It will probably take a few rounds of fiddling with the pot.
Once you’re happy with your suction control you’re ready to mount your new rheostat on your vacuum. I use the clip on the back of the new rheostat and slip it over the old mounting bracket. This is a loose attachment and the rheostat can be easily removed, which works great for me, but may not be ideal in all situations.
The new rheostat clipped onto the existing mounting bracket
I have found the only drawback to this method is the short length of the power cord on the new rheostat. However this is easily rectified by keeping an extension cord with the vacuum cleaner.
I have replaced a couple of rheostats using this method, and so far only one has needed to be re-replaced. That one worked well for about two and a half years before the ground prong of the power cord got stuck in a power outlet and we decided to replace instead of repair.
Links:
https://www.amazon.com/gp/customer-reviews/R2NOEWAOGG9JWU/ref=cm_cr_getr_d_rvw_ttl?ie=UTF8
