Dust extractor CTM26 low flow alarm

[Skooh]

Hi. It would be great to hear others experience with Festool dust extractors to help me decide what to do next.  I have a problem with the low flow alarm going off continually.  I have the correct hose setting and it occurs even with the hose disconnected and no bag installed.  I sent it back to the importer who “recalibrated the PCB” but within 5 minutes of use the alarm was back again.  As it’s practically new I feel I could request a replacement but maybe others have the same problem and just ignore it?

I also note that it leaves quite a sour smell in the air after running (like wet cardboard?). That seems to be coming from the HEPA filter itself so presumably is just glue in the filter rather than poor dust collection. Also keen to know whether others have that issue - I read somewhere else that the smell can vary depending on the batch of filters.

Thanks a lot,
Andrew

 

[mino]

Are you using the vac with or without a bag?

There should be no such smell you describe, the main filter is sterile when shipped.

It is however possible the whole vac (including the filter) was stored in a damp and cold place, then the filter can be (theoretically) ruined even before shipping, though never seen such with PET filters. There is just nothing in a PET filter what microbes can live from.

When you set the alarm to 22/27 mm hose, does is sound still ?

The hose diameter is only approximate, the air flow is restricted usually by the tool more than the hose, so e.g. for sanding one may want to set it for a smaller hose dia.

 

[Skooh]

Hi, Thanks for the reply.  I'm using a bag (which is pretty much empty).  I have the hose setting on 27 mm and get the alarm even with the hose vent open and no tool attached.  The beeping doesn't bother me too much when I'm using a tool as they're noisy anyway - it's more of pain when just using the vac by itself.  And that it isn't going to tell me when the filter is clogged and needs to be replaced.  Do you know if the alarm is a regular problem or if I got a new unit it would most likely be fine?

I only started getting the smell after it had been away for repair.  The vac arrived upside down so the bag (with some MDF dust in it) would have been in contact with the filter - might have something to do with it, or could have been stored somewhere damp over its time away.  It's definitely the filter that smells though as I took it out and left it in the sun to see if that would help (it didn't).

Thanks again,
Andrew

 

[mino]

First, I would raise a (formal) complaint that the vac was returned from repair with an apparently damaged/not-OK filter.

Second, you should send it for service again (I know, it is PITA, but they really did not fix it apparently) and make sure to write down the issue (like you did here), print it on a paper and include the paper in the package. I have it seen often that whatever is written/said to a service representative may not arrive (or is ignored/not seen) by the service technician. Not a Festool advice but a general one. If you include it on paper with the tool, you are sure that whoever is servicing the tool will get the precise description of the issue and not some "translated" one from the rep.

Lastly, then you send a CT for repair, you do not need to send the tub, when you call in you can ask to be sure but to me they told it is not needed. They do not need it (unless it is damaged and you are complaining about the tub). If you still send it with the tub, do remove the bag, they do not need it for service and if the vac ends up damp due to cold when shipping molds can develop etc. in the dust which can then transfer to the main filter even.

This raises the question - do you have the "yellow" style paper filter or the "white" style high performance one ? I assumed earlier you have the white PET HP filter, but the non-AC vacs ship with the paper version (as HP filter has no use there) which may be susceptible to molds.

Also, if the dust (in the bag) catches mold, there is nothing that can be done really except throwing the bag unfortunately, even if not full.

 

[Skooh]

Thanks for the follow up reply.  In hindsight it was a bit dumb to include the bag.  The filter is the yellow one.  So you think the smell is likely mold? I hadn’t thought of that, just assumed it was glue either from the filter or from the mdf dust.

I’ll get in contact with the rep and post back with outcome.

 

[Skooh]

Here is the final resolution in case anyone comes across this in future:  The rep visited and took the vac away.  I mentioned that it would be better not to have the alarm than have it going off continuously.  I didn’t get a notice of what was done but I’m pretty sure that it’s now been overridden as it never sounds even when the nozzle was inadvertently blocked for a few seconds. That’s still an okay outcome for me since I’m the only one using the vac.  The smell has gone as I’ve continued to use it and presumably more dust has built up.

Overall the vac is great with good suction but the alarm, which seemed a good selling point, turned out to be a real pain and ineffective in my case.

Thanks,
Andrew

 

[mino]

Here is the final resolution in case anyone comes across this in future:  The rep visited and took the vac away.  I mentioned that it would be better not to have the alarm than have it going off continuously.  I didn’t get a notice of what was done but I’m pretty sure that it’s now been overridden as it never sounds even when the nozzle was inadvertently blocked for a few seconds. That’s still an okay outcome for me since I’m the only one using the vac.  The smell has gone as I’ve continued to use it and presumably more dust has built up.

Overall the vac is great with good suction but the alarm, which seemed a good selling point, turned out to be a real pain and ineffective in my case.

Thanks,
Andrew

Not sure this helps, but on mine the alarm sounds only after a prolonged *partial* blockage. When checking it I needed to restrict the flow for several minutes. It was pretty conservative in my case so a false alarm is very much unlikely. The hose setting did not have that much of an effect either - until set to D50. But even there I needed to restrict the flow for a prolonged time for it to beep.

Do note I said restrict - it seems the computer ignores outright blockage scenarios. Guess it assumes that may be a desirable condition - like when using the vac for "second hand" helper accessories etc.

I have never managed to trigger the alarm since - never had a completely filled up vac either ... so hard to say. I would advise you keep using the vac and ignore the fullness of the bag .. to see when/if it starts screaming at you. I can imagine you will be hose-filled until you get there. But still worth it just for the curiosity.

Happy it got resolved!

 

[Skooh]

That sounds how it should be programmed.  I don’t want to try too hard to get the alarm back in case it sticks on again!  As you suggest, I’ll just keep using until full and see what happens.  I expect that will take me a long time in any case. Thanks for all your replies to my thread