Any autostart extractor that fits "Eurostandard" 36 or 50mm hose fittings will satisfy your requirements.  As you'll be installing it as a dedicated SCMS extractor, you won't be requiring such niceties as a variable speed setting, portability (wheels), wet & dry pickup, HazMat certification etc.

Just about anything from the Festool/Kraenzle range will work well, as will any of the autostart ranges from the "big 2" Euro manufacturers Starmix or Nilfisk/Alto/Wap.  The latter 2 specialist manufacturers market rebadged versions of the best of their own ranges to other large tool manufacturers such as Bosch, Eibenstock, Mafell, Metabo, etc.  Yet prices can vary wildly, even with 100% parts compatibility.  Meaning that maybe the cost of consumables (filters & bags) should also be considered.

Only Festool (I think) offer an OEM Longlife bag option, although for such a low-volume task it may not actually be financially viable.  You really only need a compact HPLV vac with autostart.  Anything with a minimum of 1 Kw power should suffice.  Anything over 1.4, or even 1.2 Kw is probably unnecessary.

There's also quite a few East Asia sourced cheapies available these days that offer autostart functionality at a fraction of the price of fancier machines.  In a dedicated installation, just about any half-decent vac can be easily & inexpensively adapted to Eurostandard hose fittings.

 CT bags are pricey if you cut a lot with the Kapex. I sold my CT 26 and now have a shop vac used with a DD and auto switch. Unlike the bags which are consumables, the DD is a one-time investment.

I got the lid and buckets (oil pails)  (use two to prevent collapsing) free from a local diner.

Google "homedepot dustopper" for some images that show a lower profile setup. But it takes up more lateral space.

I am finally building a formal Miter station for the Kapex and want to place an extractor underneath the Kapex as commonly seen.

Thanks

Consider having an enclosed feature for the extractor or shop vac to reduce nose. Even just a front door or cover will help.

This is my setup for the Kapex and DF500 (sorry for the fuzzy photo). The blue short hose (36mm-ish dia.) is for the Kapex, and another longer hose (smaller dia.) not shown is for the DF500. The autoswitch is from https://www.leevalley.com/en-ca/shop/tools/workshop/dust-collection/parts-and-accessories/63013-ivac-automatic-vacuum-switch?item=03J6210 , giving me two 15amp power outlets (one for the vac and one for the tool).

I can't remember if the CT26 was worse or better or the same as this shop vac/DD setup before I sold it. But I'm happy with the current dust collection. Not only does it save me money on the bags, it's easier to empty the bucket than replacing a bag as the shop vac need not be handled.  I agree with Alex that we're not using the great mobility feature of a CT if it's mostly tucked under the workstation.

One more note: I do not need to empty the shop vac for years (hardly any dust in the drum)! Just for precaution, I clean the filter once a year (and that reminds me I should do it this week or next week before the winter comes - https://www.leevalley.com/en-ca/shop/tools/workshop/clean-up/70445-vacuum-filter-cleaning-wand?item=03J2430).

The DD (double buckets) setup is so efficient that I have a second one for the drill press/sanding station. Dustoppers from Home Depot are cheaper I believe.

Sounds like the CT15 is a better fit than other CTs (I haven't studied the features of the CT15 though). How often the saw is used and hence bags to be replaced can be a factor. I saw a lot, and decided the bags were too much a load on the cost. Other than one-time investments, my running cost is now pretty much just electricity.

The shop vacs, though much cheaper to buy and run, do have their cons such as noise level and lack of auto-switch feature. I remedied part of those with an ivac switch and a Hepa filter (https://www.leevalley.com/en-ca/shop/tools/workshop/dust-collection/filters/64681-hepa-filters).

The Hepa filter is washable and reusable (before- and after- photos shown). I just went out and cleaned one. When it's cleaned and to be dried, I use a high performance filter (blue, also washable) instead of the one that came with the vac.

In the images, you can see the amount of dust captured in the drum after 10 months of use or so. I'm not a weekend woodworker, and so that amount is representative of average to above average use. The DDs are emptied 3 to 4 times a year.

One thing to beware of - if you aren't already - is the pitifully low (200 watt) rating of the automatic start outlet on the CT15.
I'm not sure what Festool imagines one would plug into the dust collector that uses 200 watts or less.  The ETS 150 sander, for example is rated at 400 watts.  Anything cutting or routing wood is likely to draw considerably more current (power) than the sander.

This is disappointing as I was thinking along the same lines as the OP.  It looks like you one would need an iVac or similar to plug the CT15 into instead of the tool into the CT15.

So given the low wattage of the outlet for the CT15, does that make it pretty much unviable for use with the Kapex?

How much wattage with the Kapex use ?

I’m fairly certain that Festool USA recently answered this question on one of their weekly shows. Sedge stated that the outlet will work for any Festool tool, but reading between the lines, they don’t want to rate it higher for non-Festool tools that they can’t necessarily control through soft start features, etc.

Anyone out there using the CT15 as a dedicated Kapex extractor?

I currently have a CT36 that I use for all my other tools, but I hate switching back and forth when I need to use the Kapex.

I am finally building a formal Miter station for the Kapex and want to place an extractor underneath the Kapex as commonly seen.

I really don't want to spend another small fortune for another CT26/36 just to use for the Kapex. The midi and mini are also pretty expensive to just sit underneath the saw in a permanent position.

So, does anyone use the new CT15 for this purpose?

I would plan on getting a shorter 36/50mm hose to use as a dedicated hose.
I wouldn't need Bluetooth, or mobility.

Would the CT15 be adequate for this purpose? Or is there a better extractor out there I should be looking at.



Thanks

I have both the newest midi and the ct-15. I bought the ct-15 to use as a standalone miter station DC. I would think with the auto start on the Kapex you’re okay? If not you could swap out the hose with the CT36? Or use the CT36 as the Kapex dedicated DC and the ct-15 for everything else. I got the ct-15 to leave at a jobsite without worrying about a $800 vacuum getting swiped.