Respironics DreamStation APAP - humidification

[ghstudio]

I fill my tank with distilled water every night or two, rinsing and drying it on the same schedule.  I've noticed that the water level goes down very slowly...and the plate at the bottom of the water tank is never warm to the touch.  The unit is set to auto humidification and I've tried level 2 and 4 with no apparent change in water use or my comfort.

A good friend new to xpaps and a complete non-techie was complaining that he used a full tank of water every night using the same Dreamstation Apap I have.  I looked at his machine and he was set for continuous humidification.  With his agreement, I set his machine to automatic, set the humidification level to 3 and the next night he used almost no water?????   

I guess this is a somewhat academic question because I've never had a problem with dry mouth or nasal dryness so whatever the unit is doing (or not doing) seems to be working...but I am curious how the automatic humidification works if it isn't heating that bottom plate.....and I'm interested in why my friend's dreamstation went from using a full tank of water to using almost none.  Does automatic humidification actually do something on a dreamstation or is automatic just passive humidification where the air passes over some water and picks up whatever it seems to need?

It's a mystery????

[Walla Walla]

If the air in your room has a lot of humidity than the machine isn't going to need a lot of water. It adjusts the heat in auto to add moisture as needed. In manual it provides a steady heat weather you need the humidity or not.

[Sleep2Snore]

Put it onto manual if you need more humidity and adjust it to what you need, auto will look at (or is supposed to) the humidity already in the air and only use water when there is not enough humidity, however, it is not enough for me and I have my one on manual and on 6 but I have a ResMed, but the Dreamstation I tried was set to auto and I couldn't breath half way through the night, after I put it onto manual, no problem.

[Hydrangea]

I agree that it greatly depends on the ambient humidity.  

When I'm somewhere humid, my machine uses hardly any water.  But usually - since I live in a dry climate - the whole tank of water is gone in 9.5-10.5 hours.

[Hydrangea]

I also wanted to add that your comfort may be different from your friend's comfort.

I've experimented a bit with the humidity level and heat, and found that usually I prefer auto as it provides the amount that my body prefers.

But I slept in someone's cold basement for a couple nights, and had to adjust my setting (in manual) because auto wasn't producing what I was used to and comfortable with.

I'm the type who (pre-CPAP days) can't sleep with my face under the covers because re-breathing my warm humid breath/air is suffocating to me. I feel the same when the air in my CPAP is too warm and humid. Yet I can't have it to cool nor dry because then I get dry wind-pipes (whatever they're called).

But I'm sure some people prefer their air more warm/cold and/or more humid/dry. So I'm glad we have those settings to play with.

I'll also add that when I changed my setting to be more humid, and I didn't have a heated hose (darn sleep "doctor" wouldn't prescribe it), I got some extreme rain-out that made me quickly conclude that Auto is my optimal setting. LOL (And I found another DME who automatically dispenses heated hoses.)