Hello Guest, Welcome to Apnea Board !
As a guest, you are limited to certain areas of the board and there are some features you can't use.
To post a message, you must create a free account using a valid email address.

or Create an Account


New Posts   Today's Posts

Rainout.....why?
#1
Rainout.....why?
I’ve never quite understood rainout and hoping someone can explain it to me.  
This has not happened to me before but after sleeping for about 3 hours last night I was awakened by a gurgling sound, and ended up pouring quite a bit of water out of my heated hose.
My heated hose is set to Manual, 74* and humidity at 5.  My room is around 70*. The settings were chosen by trying to reduce feeling hot at night so were basically random choices that have been working for many weeks.
What am i doing to have produced this wet tube?  Any suggestions appreciated.  Somehow,  the science of it eludes me.
Thanks for any suggestions.
Post Reply Post Reply






Donate to Apnea Board  
#2
RE: Rainout.....why?
Rainout is the same phenomenon that causes dew on the grass in the morning and condensation on a can of cold drink. The temperature of the inside surface of the hose is low enough to cause condensation of the water vapor from your humidifier. You need to reduce the level of humidity or increase the temp of the hose. I can't explain why this is suddenly happening if your humidity setting, hose temp, and room temp have not changed. I suspect one of those has changed.
Download OSCAR

Organize Charts
Attaching Charts

Mask Primer
Soft Cervical Collar

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.

Post Reply Post Reply
#3
RE: Rainout.....why?
I was just thinking that what if you set the humidifier to auto and decrease the temperature of the hose to reduce the heat setting for the hose. For me personally I'm happy with 27 Celsius and on auto humidifier.
Post Reply Post Reply
#4
RE: Rainout.....why?
(08-10-2019, 08:16 AM)mamazipp Wrote: My heated hose is set to Manual, 74* and humidity at 5.  My room is around 70*.


Clearly, since you are getting rainout now and didn't before, something has changed. The trick is finding out what has changed. One possibility is that your heated hose is broken.
Post Reply Post Reply






Donate to Apnea Board  
#5
RE: Rainout.....why?
(08-10-2019, 08:16 AM)mamazipp Wrote: I’ve never quite understood rainout and hoping someone can explain it to me.  
...
I'll give it a shot.

The air at a given temperature has a limited ability to 'hold' moisture.  As the temperature of the air rises, so can the relative humidity content.  Warmer air holds more moisture as a general rule, but not always, not everywhere.  It depends on what moisture is available for the air to 'take up.'

You can have warmish air with low moisture content, so low humidity.  It may be below its upper limit.  So, warm and drier air running over a surface with water will take up more water as it travels further and further over the water until it can't hold any more moisture/humidity.  As long as nothing else changes, the air should retain that level of humidity. 

Now, run that warm, moisture-laden air over a cool jug of milk just set upon the kitchen counter.  What do we know happens?  The air loses temperature nearest the milk because that's the way heat flows....away from itself.  It 'radiates'.  Energy always tries to find its lowest state, and it does that by attempting to warm up the cold milk jug.  Problem is, it's also laden with that maximum load of water content.  As the air loses heat, it must give up some of its moisture.  The moisture will either fall as precipitation or condense, with the latter preferred in this case.  The milk gets warmer even FASTER because, not only is it being warmed by the air flowing around it, but it's helping to draw the moisture away from the air flowing nearest the jug.

Now, imagine the room temperature air moving over the water surface in the reservoir, and it flows through a warmed hose.  No problem, and it doesn't need to give up its newly acquired water content.  But, if the hose is cooler than the air that was warmed briefly as it moved over the heated water (there's a small heater plate at the bottom of the reservoir), the flowing air cools and must give up some of that water.  It condenses just as it would flowing around the milk jug.  After a while, you have enough water to cause the hose to sag under the new weight, which encourages even more to move toward the sag, and soon you have a puddle through which the air cannot move, or the flow is sufficiently powerful that it bubbles its way through.
Serial Tapist
Post Reply Post Reply
#6
RE: Rainout.....why?
Quite a good explanation of this rainout thing.

As several have mentioned, 1 of these 3, tube or room temperature or the humidifier setting have changed. So to reduce rainout, you'll need to modify these settings until you have the desired effect.

Touching on the heated tube possible failure: how old is your tube? Any obvious signs of damage? If you've got a second one on hand, try to swap it out and see if this helps.
Dave

OSCAR
Standard OSCAR Chart Order
Mask Primer
Dealing With A DME
Soft Cervical Collar Wiki
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEBSITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
Post Reply Post Reply
#7
RE: Rainout.....why?
In the past I sometimes had this problem, I hung my hose above my head, took away the loop so any water drained back into humidifier.
Post Reply Post Reply






Donate to Apnea Board  
#8
RE: Rainout.....why?
(08-10-2019, 08:08 PM)kilowatt Wrote: In the past I sometimes had this problem, I hung my hose above my head, took away the loop so any water drained back into humidifier.

I've never had a rain out issue as of yet. My CPAP machine sits on a short file cabinet alongside our bed. The hose runs up to the top of our bed's headboard and then to a hose hanger. 

No way any water can run up the hose that way.  Bigwink
Post Reply Post Reply
#9
RE: Rainout.....why?
Hi!
ahh....thermodynamics. When the temperature of the air in the hose is below the dew point of the air, you get condensation in the hose.

I was born in Victoria; it's humid where you are. you may not even need humidification in Vancouver!

Let the machine do the thinking....Try the auto setting on your hose first. I've set temperature higher than you have. I've set it as high as I can. Frankly, I have trouble determining whether mine is working at all. I don't have rainout and that's good!

Next, if you have a defective heated hose, I bought a ResMed heated hose from a Vancouver supplier. Their price was 1/2 what i would pay locally. (Toronto). And shipping was free. You may even be using that supplier...try asking them.
DaveL
Compliant for about 30 Canadian years

I'm just a cpap user like you. I don't give medical advice. I hope to learn from you, and share my experiences with you. 
Seek the advice of a physician before seeking treatment for medical conditions including sleep apnea. Sleep-well

Post Reply Post Reply
#10
RE: Rainout.....why?
Cutting to the chase - most find that setting the tube to Auto solves most rainout issues.
Coffee

Happy Pappin'
Never Give In, Never Give Up




INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. 
Post Reply Post Reply






Donate to Apnea Board  


Possibly Related Threads...
Thread Author Replies Views Last Post
  Rainout heated humidified tube goodn 10 496 08-26-2020, 04:45 PM
Last Post: Canuck 2
  [CPAP] CPAP Rainout question(s) BB63 4 189 07-18-2020, 08:33 PM
Last Post: sheepless
  Airsense rainout: I give up, so back it goes. StevesSp 22 742 07-02-2020, 10:06 PM
Last Post: Big Guy
  Rainout problem VacantSoul 12 423 06-20-2020, 12:30 AM
Last Post: Hydrangea
  AirMini with P10 Rainout CJ797 1 466 08-20-2019, 07:41 PM
Last Post: legrunt
  Rainout! DarciWantsToSleep 2 466 03-31-2019, 12:48 PM
Last Post: DarciWantsToSleep
  [Symptoms] 5 year cpap user - suddenly, lots of loud snoring and rainout? lfreeman 2 634 03-21-2019, 12:54 PM
Last Post: dmeRT


New Posts   Today's Posts






About Apnea Board

Apnea Board is an educational web site designed to empower Sleep Apnea patients.