Knocking Sound

Last night my CPAP was making a knocking sound. I didn't know how to stop it and finally just turned it off. What the heck?

When did it start making the knocking sound?
When you first turned it on or sometime during the night?

My first thought is water in the hose. Either left over from washing or condensation that happened during the night.
Doesn't take much water to create an awful racket.

Pugsy wrote:When did it start making the knocking sound?
When you first turned it on or sometime during the night?

My first thought is water in the hose. Either left over from washing or condensation that happened during the night.
Doesn't take much water to create an awful racket.

So how do I fix it?

Do you have a spare hose? Swap out the hoses...make sure the hose is dry and see if it still knocks.

If no spare hose you can try draining the water (if there is any) out of the hose...just remove it and let it hang for a while.

If water in the hose isn't the culprit and it still knocks immediately when you start the machine...call your equipment supplier.

And an answer to theses question would be really helpful.

Pugsy wrote:When did it start making the knocking sound?
When you first turned it on or sometime during the night

Pugsy wrote:Do you have a spare hose? Swap out the hoses...make sure the hose is dry and see if it still knocks.

If no spare hose you can try draining the water (if there is any) out of the hose...just remove it and let it hang for a while.

If water in the hose isn't the culprit and it still knocks immediately when you start the machine...call your equipment supplier.

And an answer to theses question would be really helpful.

Pugsy wrote:When did it start making the knocking sound?
When you first turned it on or sometime during the night

Sorry didn't see the questions. It did not start when I turned on the machine. It was later during the night. I don't have an extra hose but I will take the hose off and hang it to dry.

Starting later in the night certainly sounds like rainout due to condensation. Do you have a heated hose?

Place your machine lower than your bed so any water runs back into the humidifier or raise the hose by routing it over the headboard or making a hose hanger with command strips and ponytail hair holders that you run your hose through. There are also commercial hose holders that you can buy.

Wrap your hose to keep it warm with fleece or tube socks with the toes cut out and rubber bands. You can also buy a zippered hose cozy at cpap.com

Most likely it was water in the hose.
I had it happen to me just 2 nights ago. New machine and no heated hose. Makes a horrible racket.

When in doubt you can always remove the hose and try the machine without the hose. If there's no knocking then probably water in the hose.

Rain out/condensation in the hose..and if that is what it is there are options that you can try to limit it.
See this thread posts number 2 and 3...several options there.
viewtopic/t94035/Pugsys-Pointers-3Deali ... -road.html

Side note...you may see where people tell you to just raise the hose up and let the water drain back into the humidifier but that doesn't always work so great because a lot of the machines now have a little elbow at the humidifier to hose junction and that little elbow prevents good draining. It didn't work so great for me and that's how I figured out that just letting gravity help didn't totally remove the problem. It doesn't take but just a few drops of water adhering to the inside of the hose to cause a whole lot of noise and sometimes those drops are really stubborn.

As many have already said, it's probably water in the hose (i.e. condensation, which is often called "rain-out").

In addition to the suggestions already made (which are good ones), please be very careful not to overfill your water tank.

Pugsy wrote:Most likely it was water in the hose.
I had it happen to me just 2 nights ago. New machine and no heated hose. Makes a horrible racket.

When in doubt you can always remove the hose and try the machine without the hose. If there's no knocking then probably water in the hose.

Rain out/condensation in the hose..and if that is what it is there are options that you can try to limit it.
See this thread posts number 2 and 3...several options there.
viewtopic/t94035/Pugsys-Pointers-3Deali ... -road.html

Side note...you may see where people tell you to just raise the hose up and let the water drain back into the humidifier but that doesn't always work so great because a lot of the machines now have a little elbow at the humidifier to hose junction and that little elbow prevents good draining. It didn't work so great for me and that's how I figured out that just letting gravity help didn't totally remove the problem. It doesn't take but just a few drops of water adhering to the inside of the hose to cause a whole lot of noise and sometimes those drops are really stubborn.

Yes. Mine has the little elbow. This is a very frustrating problem.

It's physics. Cool room air on the outside meeting warm air on the inside and condensing the water vapor on the tube walls. If you don't have a heated hose, consider one. Find ways to keep your hose warm, like suggested above or put it under the covers. The other option is to increase your room temperature.
It can be solved but may take some experimenting.

KTinTexas wrote: Yes. Mine has the little elbow. This is a very frustrating problem.

Yeah. I was really perturbed at about 4 AM yesterday morning when I was having rain out city in my hose and holding the hose vertically so it would drain..didn't work. I was thinking "what the hell...why won't it work" but at 4 AM I wasn't thinking so clearly but when I finally woke up later and looked at the physics involved...it was easy to see that the elbow could have impacting the drainage a bit. Or the fact that the attachment goes out horizontally behind the machine and makes its own little elbow.
One nice thing about the PR S1 was the hose attachment on the top of the lid....makes for much better draining.

Is your hose a heated hose or just a regular non heated hose? If it's a heated hose you can just increase the hose air temp and that usually will prevent the condensation quite easily.
If your hose is a non heated hose then you have to try something else.
Either warm up the air in the bedroom or warm up the air in the hose somehow or try reducing humidity output (lower humidity setting but your nose might not like the drier air).

I had a hose cozy from long ago when there weren't heated hoses and the only way I could keep that air warmer was with a hose cozy.
You can make your own though if you don't want to buy one or wait on one.
My first homemade hose cozy was just some old worn out socks of my husband...cut the toes off and slid the socks over the hose and secured with tape. Or just wrap some fleece around the hose and tape it down.

Easiest fix though is just warm the air up if you happen to have a heated hose. Sometimes it only takes 2 or 3 degrees to keep the air from cooling to the point of releasing the moisture.

I don't have a heated hose. I need to look into getting one.

KTinTexas wrote:I don't have a heated hose. I need to look into getting one.

The good news is that one is available for all of the DreamStation models.

I too have a Dreamstation - approx 7 months old. After 3 months a knocking/clicking sound began. After testing hoses testing at the local supplier's shop we discovered it was the humidifier. They replaced the humidifier and all was good.
Fast forward another 3 months and the knocking/clicking sound started again. I rang Philips (as supplier shop was closed early) and was told it is a known fault - approx 1 in every 10-15 machines has the same problem. They said return it to shop and humidifier will be replaced AGAIN!
The supplier has returned it to Philips so they can check it out and possibly replace the whole unit. This will take approx. 4-6 weeks.