ResMed S9 series (S9 AutoSet, S9 Elite, S9 Escape)

How to set up the ResMed S9 series (S9 AutoSet, S9 Elite, S9 Escape)

From the box to your first night. Keep the user guide that came with your machine nearby: if anything here differs from it, follow the guide.

  1. Attach the H5i humidifier

    If you have the H5i, line it up with the side of the S9 and push them together until they click. Do this with the water tub empty; ResMed says the H5i should only be connected or disconnected when the tub is empty.

  2. Connect the power

    Push the DC plug of the power supply fully into the back of the S9, connect the power cord to the power supply, then plug the cord into the wall. Use the 90W power supply when the H5i is attached; the 30W supply is for the machine alone.

    Keep the power supply out from under bedding and away from the H5i so it can stay cool.

  3. Fill the water tub

    Slide the latch and lift the flip lid, take out the water tub and fill it through the center hole with distilled or deionized water up to the maximum mark (380 mL). Put it back and close the flip lid until it clicks.

    Use room temperature water, not hot or ice cold water, and never overfill it.

  4. Connect the tubing and mask

    Push one end of the air tubing firmly onto the air outlet and connect your assembled mask to the other end. If you use ClimateLine heated tubing, it connects to the H5i; it is not designed to connect directly to the S9 alone.

    Set the H5i on a level surface below the level of your head so water cannot run into the tube.

  5. Tell the machine your mask and tube type

    Press the Setup key, turn the dial to Mask, press to select, turn to your mask type and press to confirm. If you use SlimLine or Standard tubing, make sure the matching tube type is selected in the menu too, because the wrong tube setting can make the air feel weak.

    If your clinician turned on S9 Essentials, these menus are hidden and that is normal.

  6. Set humidity and ramp

    From the Home screen, turn the dial to Humidity Level, press, turn to a level from Off to 6 and press to confirm. Do the same on the Ramp screen to choose a ramp time.

    If you want warm water at bedtime, use the warm-up: go to the humidity screen and push and hold for three seconds until Warming Up appears.

  7. Check your mask fit

    On the S9 AutoSet and S9 Elite, use mask-fit before sleep: with the mask on, push and hold as shown in the Welcome Guide for three seconds from the Home screen. The machine blows treatment pressure for three minutes so you can adjust the cushion and headgear until the screen shows a good fit.

  8. Start therapy

    Lie down, breathe into the mask or press Start/Stop, and arrange the tubing so it can move as you turn. If your clinician enabled SmartStart, therapy starts when you breathe into the mask and stops when you take it off.

    After you stop, the S9 may keep blowing air for up to an hour to cool the H5i heater plate. That is normal.

After setup: settings worth knowing

  • Ramp time: Starts at a low pressure and raises it to your treatment pressure over the time you choose, to help you fall asleep.
  • Humidity level (H5i): Sets how much the H5i heats the water, from Off to 6. Higher means more moisture.
  • Climate Control and heated tube temperature: Available only with ClimateLine or ClimateLineMAX heated tubing. It adjusts air temperature and humidity to cut down on condensation; you can set the tube temperature for comfort.
  • H5i warm-up: Preheats the water in the tub before you start therapy.
  • Mask type: Tells the machine which kind of mask you use so it handles leak and SmartStart correctly.
  • Tube type: Matches the machine to SlimLine or Standard tubing so it delivers the right pressure at the mask.
  • SmartStart/Stop: Starts therapy when you breathe into the mask and stops it when you take the mask off. S9 AutoSet and S9 Elite only.
  • EPR (Expiratory Pressure Relief): Lowers the pressure as you breathe out so exhaling feels more natural. ResMed offers level 1 (mild), 2 (medium) or 3 (maximum).

How to change each one →

Supplies that can help

Distilled water for CPAP humidifiers

Distilled water is what most CPAP humidifier chambers are meant to be filled with, because it leaves little or no mineral scale behind.

AmazonCPAP.comAffiliate linksHow to choose
Replacement CPAP air filters

The air inlet filter keeps dust and lint out of the machine and your airway; it is a cheap part that needs regular replacement.

AmazonCPAP.comAffiliate linksHow to choose
Standard (unheated) CPAP tubing

The plain hose between the machine and the mask; it wears out and should be replaced on a regular schedule.

AmazonCPAP.comAffiliate linksHow to choose
Mild unscented soap for CPAP cleaning

Plain, mild dish soap is the cleaning agent most CPAP makers and the FDA point to for masks, tubing and humidifier chambers.

AmazonCPAP.comAffiliate linksHow to choose
CPAP hose cleaning brush

A long, flexible brush sized to reach the full length of CPAP tubing so you can scrub the inside, not just soak it.

AmazonCPAP.comAffiliate linksHow to choose
CPAP hose hanger

A simple hook or hanger for drying CPAP tubing vertically after washing, and for keeping it off the floor.

AmazonCPAP.comAffiliate linksHow to choose

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Sources

Last reviewed October 11, 2026. How we research · Report an error