Humidity question.

[Chris333]

I'm using a Resmed S9 autoset with the H5i humidifier. Also using a NON heated slimline hose. Recently I got a coupler and another hose to double the length. This let me move in my bed better, but I also for the first time got the gurgling sound(from rainout?) that woke me up. I didn't get wet, but there was water in the tube. It was the sound that woke me not wetness.

So I'm looking into getting a hose sleeve.

Until then I turned down the humidity level on the S9 and this got me thinking... The air just blows over the water so how is it possible to adjust the humidity at all? What happens when I turn it down? The air still blows over the same water the same way. If it matters the level was at 5 and I'm going to try it at 2 tonight.

Just wondering what I'm missing.

[Julie]

That the hose (at the machine end) was at a higher level than your head, therefore not allowing the water to run back to it, but give you rainout? Put the machine at a lower level by a couple of inches.

[cands]

Until then I turned down the humidity level on the S9 and this got me thinking... The air just blows over the water so how is it possible to adjust the humidity at all? What happens when I turn it down? The air still blows over the same water the same way. If it matters the level was at 5 and I'm going to try it at 2 tonight.

Just wondering what I'm missing.

Well, not quite the same way. The water is heated. There is a heater element under the water chamber. The higher the humidity setting, the hotter the water, hence more evaporation and higher humidity.

[D.H.]

Yes, put the machine lower than you head as already suggested. Also, make sure not to fill the water chamber higher than the full line.

If you still have the problem, try lowering the humidity setting and/or using a heated hose.

[Pugsy]

When you use the S9 humidifier without a heated hose the machine uses an internal ambient room humidity sensor to figure out a starting point for the humidity and then with your selection choice (1 through 5) the machine will warm the water enough to try to maintain whatever humidity level that particular number relates to.
I have never really understood how it senses the end result after the warming but I accept that it at least tries to maintain whatever humidity that setting means.

As someone already mentioned...the warmer the water the greater the amount of moisture the air blowing over the water will pick up and deliver. Warmer water releases moisture easier and faster than cooler water and warm air (byproduct of the heating of the water) holds more moisture than cooler air.

I suspect that what happened with the added hose length causing rain out that you never had before is from that warmer air (byproduct of heating the water) having to go farther to reach the mask and the added distance is allowing the humidified air to cool down to a point where it can't hold on to the moisture and condensation occurs.

You have several options...turn down the humidity setting so that the air doesn't have as much moisture in it so less chance of the air not being able to hold on to it all as the air cools.
...use a hose cozy in an effort to prevent the air from cooling too much before it makes its way to your face.
...warm up the ambient room air temp so that the air in the hose is less likely to cool to the point of releasing the moisture.
...placing the machine lower than the mattress may or may not work well because with the added length there's likely to be some places in the hose where there's no direct downward positioning of the hose to allow gravity to help remove the moisture. And if you are using a hose hanger routing the hose over head then machine placement is likely to make zero difference because water can't run uphill. If there is anywhere in the hose placement that the hose lays flat or goes up...that's a place where condensation can pool no matter where the machine is.
...you could add the heated hose as the first hose and maybe with the added warmth available in the first hose the air in the second hose won't cool so quickly as to release the moisture. The air will be entering the second hose much warmer than it would be if you don't use a heated hose.

[chunkyfrog]

The heated hose for that machine is well worth the small difference in cost.
Cpap.com shows the cost difference around $7. (DME may want more)

[Chris333]

No DME for me, all Craig's list and E-bay.

Thanks guys. I had no idea the water tub was heated. Doh! And with the humidity level set to 2 I slept all night without waking up or hearing noise. The hose did have condensation when I woke up, but nothing woke me.

[Pugsy]

Having water in the hose or mask won't hurt you but it can sure be highly annoying.
I have had it happen and a teaspoon of water in the hose made so much racket it woke my husband who was muttering "what the hell is wrong with your machine?"

So a little water hurts nothing as long as it doesn't disturb your or your spouse's sleep.