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S9 broken?
I have had my S9 unit for two years now, and suddenly it seems to be broken. The unit starts out just fine each night, but after about 4 hours the pressure drops and when I inhale the machine/blower makes a loud noise like I am making the blower spin faster by breathing in.

Normally, my pressure setting 17 means I really don't have to inhale hard to take in air. But now 4 hours I to treatment each night, the pressure drops and I have to inhale deeply to get air and this causes the blower to spin faster making a loud noise.

Any suggestions on a fix?
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That sounds like it has an issue. Have you verified your setting are still the same? After those four hours, when it starts to act up, does the machine feel warmer than normal?

Using FlashAir W-03 SD card in machine. Access through wifi with FlashPAP or Sleep Master utilities.

I wanted to learn Binary so I enrolled in Binary 101. I seemed to have missed the first four courses. Big Grinnie

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Download the Sleepyhead software http://www.sleepfiles.com/SH2/
Check your data and see if the pressure is actually dropping, or if there might be some other explanation (leak).
If you are hearing motor sounds, you may have a mechanical issue that requires repair or replacement. Which model S9 are you using (Escape, Elite, Autoset?). Finally with a pressure of 17, you might want to inquire about a bilevel (VPAP/BiPAP) for your next machine.
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Doesn't feel warmer, just lower pressure and a loud whirring noise from the blower when I inhale. Seems odd that it will work fine for a few hours. I would think if blower was broken it wouldn't work at all.
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S9 Autoset. Data doesn't show any pressure change, only that I wake up after four hours and therapy is interrupted as I try to get it to work.

I took it to my provider and they ran it for about 40 mins and pressure gauge showed 17, and no issues. Still under warranty so they will replace machine, but they no longer sell the S9 so they gave me a System One to try but I can't get that machine to humidify adequately (started another thread on this issue).

I really like the S9 and am hoping I can find a fix.
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Hi Roemere,
WELCOME! to the forum.!
Hopefully, you can get your machine fixed or replaced.
Much success to you with your CPAP therapy.
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Since the blower is an impeller type, it does indeed speed up when one inhales. Has to speed up to keep constant pressure with the higher outflow. I can hear it speed and slow on my S9.

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It is difficult to diagnose over the internet, but speaking as an Engineer this sounds like worn bearings in the motor, or something in that category. This is also the only moving part, and so is the only part susceptible to mechanical wear.

When bearings wear, sometimes this increases friction, which causes heat to build up, and then expansion just aggravates this and it gets worse. The blower can't blow like it should because the fan is unable to overcome the friction. If so, this will only get worse and worse. It will run "kinda" OK until the heat builds up, and then when it does, it has bigger issues. Then eventually, it just won't run. It probably is a safety issue, so do not ignore this; you do not want to set the bed on fire.

This can be fixed pretty easily by replacing the motor. A qualified repairman with access to these parts can do this. It may also need some calibration afterwards, so you may be able to just replace the motor, but you probably want a ResMed qualified person to do this. Probably not cheap, even if you get the motor and replace it yourself, which takes just a few minutes. They build everything so it is impossible to open without knowing the secret handshakes, so that is the toughest part.

If it were me, and I wanted the old S9 at least as a backup, I would find a motor and replace that myself, assuming the cost were not prohibitive, and then probably not worry about the calibration all that much (it's a backup!). Since you will have a replacement, this can be your backup. If the S9 runs like new once fixed, then the new one can be the backup if you prefer the S9.
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My thoughts exactly as far as the bearings are concerned.

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(07-31-2015, 03:59 PM)justMongo Wrote: Since the blower is an impeller type, it does indeed speed up when one inhales. Has to speed up to keep constant pressure with the higher outflow. I can hear it speed and slow on my S9.

I am not sure it would matter whether it is an impeller or not. Also, we are talking about a small volume of air in an otherwise partly-closed (vented) system. If it were speeding up and slowing down to maintain precise total pressure (a function of static pressure combined with velocity pressure), a change in fan speed would probably be imperceptible in that small volume at these relatively weak pressures, because the change in static (and therefore in the total) pressure as you inhale and exhale is very minimal. But it probably is not maintaining precise total pressure anyway, because there is no therapeutic reason for it to do that.

The pressure is based on cm of H20 (how far a column of water will rise when static pressure combined with velocity pressure is applied to a pressure tap in the airflow), so these are tiny differential pressures compared to atmospheric pressure or an increase of a couple of PSI in a tire.

The CPAP bases pressure settings on velocity pressure, which is set to be constant, even though the total pressure in the system might vary slightly through the respiration cycle due to slight changes in static pressure when you breathe in and out. Compare the airflow of a normal exhale to the airflow of a xPAP putting out 10-15 cm, and the difference is pretty great.

The static pressure varies slightly as you breathe in and out, so the total pressure does vary slightly, but not enough that the velocity pressure must be modulated by the xPAP to keep the total pressure constant. There is no real therapeutic advantage to having the tiny change in static pressure variance compensated for by modulating the velocity pressure.

Also, the pressure of CPAP is therapeutic only during inhalation; there is no need to have that pressure maintained all that precisely during exhalation, and for the few patients where significant EPAP control is necessary, a CPAP is not prescribed anyway.

OSA is a problem with airway collapse on inhale. The airway does not generally collapse on exhale. So whether the total pressure in the system goes up during exhale is not relevant to the therapy, and compensating for that change in total pressure during exhalation is not needed.

IOW, the total pressure does not need to be maintained that precisely, only the velocity pressure to assist inhalation. The therapeutic difference between a pressure of 10 and a pressure of 10.1 is probably not even discernable medically, which is probably why the granularity is not any greater than that.

That applies to CPAP fixed-brick pressure. If you have an auto machine, or an ASV, VPAP, or a Bi-PAP, or if you are using pressure relief for inhale, certainly velocity pressure and therefore total pressure will vary, and you might be able to notice that. But a properly functioning S9 AutoSet should be absolutely silent regardless what velocity pressure it is putting out or how much it may be varying.
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