S8 Autoset II Still pushing air when off

[no1psycho]

Brand new to this whole CPAP thing. Just started using mine about a week ago. I was just wondering about the machine I have. When I stop it in the morning there is still a little air continuously coming out of the mask. Originally I thought that it just took a little bit to totally shut down but I checked it this morning after about 30 minutes and there was still air being pushed out of the mask. If I unplug the unit it stops. Is this a normal thing or should I worry that I have a messed up CPAP machine?

Thanks a lot for all of the GREAT info on this site!!!!

Greg

[tyropita]

Some of the S8 units blow air gently for about an hour to dry out the hose. The Escape I used for my trial did not, but the Elite II I have now does.

[no1psycho]

Some of the S8 units blow air gently for about an hour to dry out the hose. The Escape I used for my trial did not, but the Elite II I have now does.

Alrighty, thanks for the info. I just wanted to make sure before I go back to the DME.

Greg

[BeanMeScot]

That's a nice feature!

[Debjax]

Called our DME last week when we noticed hubby's doing that. She told us it is normal for up to an hour....not to worry.

[tattooyu]

I just got my Autoset II and noticed the same thing. I think it's actually pretty cool to have it dry the hose out.

[Velbor]

This is not so much a function of the S8 as it is of the S8/Humidaire combination. The S8 will not blow after therapy unless the Humidaire is connected.

And the purpose has nothing to do with drying out the tubing. The Humidaire manual reads, "Some flow generators continue to blow air gently after you have stopped your treatment. This can continue for up to one hour to assist the heater plate in cooling."

In fact, this explanation is a bit misleading. The principal concern is that if you have hot water in the humidifier chamber, you have air above the chamber which is supersaturated with water vapor (with respect to room temperature). With treatment stopped, that supersaturated air can diffuse in either direction; nothing prevents it from entering the blower. Once the blower cools down (ResMed machines tend to run a bit warmer than Respironics since they have the power management transformer inside the casing, but they still cool down fairly quickly; water, on the other hand, has a very high specific heat rating, and stays warm a long time), the warm moist air can condense and form "rainout" inside the machinery. This is what the continued blowing is designed to prevent; it protects the blower by keeping the humidified air moving in the other direction; the hose is in fact irrelevant and is arguably put at greater risk of rainout moisture than without the gentle blowing.

For precisely this reason, regardless of machine, it's a prudent suggestion to disconnect or remove the humidification chamber from the system (both sides, machine and hose) in the morning. Whatever else you may or may not choose do with the chamber and the warm water inside is another issue.

Regards, Velbor

[sleeplessinaz]

Hi VELBOR---WOW--no one ever told me to "disconnect or remove the humidification chamber from the system (both sides, machine and hose) in the morning"--i never do that. I do however, lift the cover off the humidaire chamber to let the moist air escape. I cannot see taking the whole unit apart every morning!! that sounds rediculous and why did the DME not ever tell me this?

C

[JayC]

I don't use the humidifier....and never have as of yet. My "blower hours" have increased some over and above the "usage hours". So, the blower continues (at a very subtle level) even when no humidifier is connected........according to my experience.

WHen I got the machine, blower and usage were within one hour of each other. At this time, blower and usage are within 3 hours of each other....

J

[Velbor]

I do however, lift the cover off the humidaire chamber to let the moist air escape.

Given the geometry of the H3i humidifier, lifting the cover effectively DOES physically disconnect the chamber from both the blower and from the tubing. The older ResMed S7 H2i system does not have this option, nor do most stand-alone systems. I cannot speak directly to other manufacturers' integrated humidifiers. This stuff is simple physics. Regards, Velbor