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Odd problem with air flow with Dreamstations - Printable Version

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Odd problem with air flow with Dreamstations - racprops - 09-15-2020

I seem to have noted an odd and performance lowering behavioral of my new Phillips Dreamstation ASV.
 
I have had higher AHIs for the past three weeks.  Nothing bad, still low and under 5per night, but nothe first two nights lows of less than .5.
 
Last night I noted a lower that normal (first two nights worth) air flow.
 
WTF??? So I unplugged the system to cause a reboot….and it worked I got a notable improvement to air flow.
 
But due to the impact of the air start up air, which is a little more a hit than the older 950/960 systems,  I began starting the system with the hose disconnected from the mask, until it was up and running.
 
I did that after the reboot a second power up and the air flow was reduced…so a reboot again and I kept the air hose connected and took the “hit” of the startup and the air flow stayed full.
 
My best guess as to what is happing is there is a fan speed control, like a REV Limiter on cars, and with no back pressure on the hose (IE open) it cuts in and lowers the fans top speed so it does not over rev.
 
BUT it seems this control once turned on does not completely shuts down and when I hook the hose after allowing it to run wild it stays slightly in control lowing the air flow.
 
So I report this to ask has anyone else seen this with their systems, and for the techs to say if I am right.
 
The next couple of nights will also help prove my theory by how well I do sleep wise.
 
Rich