Machine height and humidity

Hi folks
Been a while.
So I read in the instruction manual the machine should be slightly lower than the mattress.
I have had several nights where it seemed like the machine did not use up any water no matter what I had the humidity set to.
So I put it on a lower table and with the humidity set to 5 (max) it would use all the water in the reservoir and I woke up feeling great. That lasted about 3 nights.
Then last night I had the same set up and it was like it used almost no water again. My mouth was very dry and I am not feeling as awake today.
So how high relative to the mattress do you keep your machines?
What humidity level seems to work for you?

I have the same problem sometimes I almost drowned and some nights it takes no water. Has my on 5.5!

The ability of your machine to humidify the air with the water in your tank has nothing to do with the height of the machine. Unless your ambient air humidity is changing quite a bit from day to day, I think the problem lies either in your humidifier itself (maybe the heater?), or some setting you changed by mistake.

The recommendation for slightly below mattress level is more for using gravity to help reduce the annoyance of condensation in the long hose. It really doesn't have anything to do with how much water is used or not used.

Water usage depends on the type of humidification system that is being used...with the Respironics machines that would be
heated hose or not system...several options there
the default new humidification system...doesn't use much water especially if the ambient room humidity is rather high
or Classic mode...which is heat only and uses the most water

and also depends on pressures used along with leaks and finally....ambient room humidity.

What model machine do you have...is it a 50 series or 60 series?
Your machine choice in your profile points to the PR System One Plus CPAP with CFlex which is model 250.
No heated hose option with it. The default humidification system s for the new humidification system which doesn't use all that much water even at a setting of 5 if there is much ambient room humidity.

If you have a different model (the number is on the bottom of the blower unit) you might have additional options but if you have the 250 model about all you could do to use more water (if your nose needs it) is to switch to Classic Mode and see if that helps. It will use more water but also increases the chance of rain out.

Has it been raining lately where you live? When it rains here where I live I won't use much water at all and other times I might use nearly the entire tank with my max settings.

And Windsor's very near the water - ambient humidity makes a lot of difference to what's used.

Ambient humidity has very much effect on water usage, as does mouth-breathing with a nasal mask.

I started cpap in Feb. 2014, and nearly every night my water tank ran dry... completely dry. In a week my gallon of distilled water would be gone. I wondered if it would be like that every night for the rest of my life. I learned that here in Minnesota, as in the rest of the Upper Midwest, winter air is very dry, and that is why it was going dry. Now that summer is here with humid weather and tons of rain, I fill my tank barely half full and there is still water in it when I wake up in the morning. As ScOtt said, ambient air makes the difference, and there are many factors involved... does the home have central air, what's the weather like, etc. There's likely nothing wrong with your machine, just environmental things.