humidifier and water useage

I've noticed that the amount of water used by the humidifier on my cpap varies greatly night by night. Last night, I had the setting up to 4 (on a 5 scale) and only a small portion of water was used. In the past on that kind of setting the entire tank would almost be used (the amount of sleep was about normal). I'm curious about this, but also about a larger question: is my humidifier working properly? How does one tell? Is there a way to do some kind of diagnostic test on the thing? Appreciate anyone's thoughts, thanks.

Your humidifier responds to ambient humidity like anything else - if it rains one night, you will use next to no water at all, but if you're in Arizona, may use a full tank every night.

Julie wrote:Your humidifier responds to ambient humidity like anything else - if it rains one night, you will use next to no water at all, but if you're in Arizona, may use a full tank every night.

Almost Full tank every night at the lowest setting 60F. Phoenix Metro Area, Arizona. Wish the tank was larger. Resmed not Respironics, but my previous M-Series was similar.

You can use the preheat function available on your machine and let it preheat for about 15 minutes and then pull the water chamber out to feel if the bottom of the chamber is warm or not..it won't be extremely hot though.
That's pretty much the extent of any testing procedure...if it's warm it works. Not perfect test but all we have.

Water consumption will vary depending on how much moisture or humidity there is in the air in the bedroom to start with.
If the humidity is already fairly high (like raining outside and windows open) the machine will sense that and not heat up very much because it simply doesn't need to add much, if any, moisture to the air from the machine.
I pretty much max out my humidifier setting all the time. Some nights I use all the water and some nights it barely uses any water...like when it rains or has rained recently. It is this way with both my PR S1 and S9 machines.

Thanks.