knocking noise

My machine has suddenly been making a knocking noise at night which wakes me up. does anyone know why this is happening? Started using my machine in January 2014.

I would be contacting your supplier ASAP about this.

Have you moved it to another location to see if it still knocks. Could be a vibration? What do you have it sitting on?

Are you sure it is not a popping noise, normally caused by water in the hose?

If so, Lift the mask end of the hose higher to run any water back to the water chamber.

patpra wrote:My machine has suddenly been making a knocking noise at night which wakes me up. does anyone know why this is happening? Started using my machine in January 2014.

Since you are relatively new to CPAP therapy there are some helpful things to do:

1. Get a copy of your sleep study and your sleep titration study. They have interesting information that will help in understanding your child's therapy

2. Get a copy of your prescription for your own records. It will be necessary if you choose to change DME's or order online

3. Post your equipment. There is a link on how to do this in my signature block below. Please select TEXT as a display choice as many CPAP machines and masks appear similar but are significantly different

4. If you need to post images of your reports, there is a link in my signature block on how to post using PhotoBucket.com

5. While the LCD display is somewhat useful, it is better to use one of the reporting software programs to get detailed information on your therapy. The two available for Respironics machines are: Encore (Basic or Pro) and SleepyHead.
If you have a ResMed machine, the SleepyHead and ResScan are the programs of choice.

My machine make a popping noise from the anti-asphyxiation valve when I first start but it goes away after everything starts. It also makes a similar noise when the rainout is not controlled well enough. Check inside your hose to see if there is water condensation inside. Using a hose hanger or getting some insulation wrap around the hose will help that condition.

Perhaps placing a small towel under your machine will help suppress the noise.

If none of these things help, then do contact your DME for assistance as this might be a warranty issue and sooner is better than later.

I thought about making a 'knocking usually means you need premium fuel and are using regular, or perhaps you've gotten carbon buildup... now, if it's a regular tapping, then you're probably having valve lifter problems, or are about to throw a rod' joke,

but decided against it.

then I thought "if it's knocking, have you tried answering it?"

patpra wrote:My machine has suddenly been making a knocking noise at night which wakes me up. does anyone know why this is happening? Started using my machine in January 2014.

It's highly likely that your humidity setting is too high (and your room temperature is cool) and the water is condensing in a low spot in the hose, causing the water to restrict the air trying to get past it. Thus the knocking noise. Turn your humidity setting down and make sure the hose doesn't have a low spot in it.

Welcome. Please sign up for an ID and fill in the equipment on your profile so we know what equipment you have.

You've almost certainly got water in the hose. Carefully disconnect the hose at the CPAP machine, and hold the end up so water doesn't pour out. Then hold the mask end of the hose up as well so the water is trapped. Go to the sink with this and gradually work your way down the hose to see if any water pours out.

What happens is that enough water condenses to block the hose. The air will push through the obstruction, making bubbles and a knocking noise.

If that's your problem, it's what we call "rainout." There are various ways to handle this. Turning down the humidity, or rerouting the hose so water doesn't collect in the hose may help it. Depending on your machine, there may be an optional heated hose that will prevent condensation. You can also use a "hose cozy" to keep the hose warm and that might help.