S8 v S9

I have been offered a used S8 Autoset II complete. Asking price is $400 but I think it will sell for less Under 1200 hours. The humidifier is a 3 but all the info I can find online shows a 4 for that unit. Questions: Is the S8 a good unit? What features of the S9 are different than the S8? Does the unit use a SD card or some special card? Anything else I should know? I see there is an autoset II and a Spirit autoset II. What are the differences Thanks

Bob

S8 autoset II and S8 Spirit II are different names for the same machine, Autoset in the States, Spirit in Europe an Australia.
They S8's user a proprietary card and need a card reader that is hard to get.

S9 uses and SD card - not proprietary.

The altorhithm is different:
Breathing is easier and smoother with the S9
The S9 does not respond when it identifies a central apnea at pressure lower than 10 - the S8 does. Which means the S8 may drive your pressure too high, if you happen to have central apneas at pressure lower than 10.
The S9 is better at responing to apneas above a pressure of 10 too.

Reporting:
You ger far more details on the S9 than you do on the S8. The S8 does not even show you snores.

On the other hand the S8 Autoset Spirit II is a still decent machine. For under $400 for less than 1200hrs, you're laughing.

The H3i was the original humidifier for the S8 series. It was upgraded to the H4i somewhere along the line.

There is an upgrade kit that converts an H3i to an H4i. It costs $36.

https://www.cpap.com/productpage/resmed ... r-kit.html