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    HumidAire H4i™ Heated Humidifier

    HumidAire H4i™ Heated Humidifier

    The HumidAire H4i™ Heated Humidifier by ResMed is compatible with the S8 line of machines. It features improved performance and capacity versus its predecessor, the H3i.

    Manufactured by ResMed.

    The HumidAire H4i™ Heated Humidifier by ResMed is compatible with the S8 line of machines. It features improved performance and capacity versus its predecessor, the H3i.

    Product Features

    ResMed's HumidAire 4i is engineered to deliver 30% more heated humidification than the H3i. The humidifier is an integrated unit for use with ResMed S8 and S8 II series CPAP machines. The H4i Water Chamber has also increased in capacity up to 390 ml of water.

    The HumidAire 4i provides relief from symptoms such as dry nose or mouth, irritation, and congestion sometimes related to CPAP therapy without jeopardizing performance or convenience.

    Nasal CPAP users generally experience congestion and dryness of the nose and throat. The warm moist air that humidification provides has been proven to relieve symptoms of dryness and can make therapy more comfortable.

    Fliptop lid design - water chamber fills without removing the tubing.

    Small design - unobtrusive on the nightstand and easy to pack for travel.

    Seamless integrated unit - snaps onto the CPAP machine whenever needed.

    390 ml capacity - very efficient humidification with a high volume.

    Powered by ResMed S8 and S8 II Machines - no extra outlets or power supply necessary.

    Simple Dial Control - easy to utilize in darkness and fast to respond.

    Return On Warranty Issues Only


    This Product Includes...

    • Humidifier
    • Chamber

    Product Specifications

    Maximum Heater Plate Temperature: 185°F (85°C)

    Temperature Cut-Out: 199°F (93°C)

    Dimensions of Chamber and Docking Station: 5" x 6.7" x 8.3" (118mm x 164mm x 145mm)

    Weight of Docking Station and Unfilled Water Chamber: 1.6 lb (732g)

    Water Capacity: 390ml to Max Fill Line

    Power Supply Input Range: 100-240V, 50/60Hz; 110V, 400Hz; 2.5A < 140 VA (110 W) (maximum power consumption)

    Maximum Heater Element Power: 85 W

    Docking Station Materials: Flame Retardant Engineering Thermoplastic,Plated Cast Aluminum

    Water Chamber Materials: Injection Molded Plastic, Stainless Steel

    Operating Temperature 41°F to 95°F

    Operating Humidity 10-95% Non-Condensing

    Storage and Transport Temperature -4°F to 140°F

    Storage and Transport Humidity 10-95% Non-Condensing

    IEC 60601-1 Classification: Class II (Double Insulation); Type CF

    Electromagnetic Compatibility: Product complies with all applicable electromagnetic compatibility requirements (EMC) according to IEC60601-1-2, for residential commercial and light industry environments.

    *Consult the medical department of the carrier before using on aircraft.

    Warranty Length:

    • Heated Humidifier - 1 Year
    • Water Chamber - 90 Days always offers these services:

    • 8 am to 10 pm CST Toll Free Phone and Email Support
    • 24 hour access to our Support Forum
    • Learning Center for information on sleep apnea and cpap equipment
    • Consumer Purchasing Trends Reports
    • Warranty Services for all items purchased through
    • Insurance Compliant Invoices
    • Free Prescription Request System

    Manufacturer Note

    • Some product images supplied by ResMed © ResMed 2010 Used with Permission.
    • ResMed products are for sale only to patients within the U.S. and not to other third parties or businesses.
    • A valid prescription is required for the purchase of this product.
    • All services provided by, including advertisement, ordering, sale, delivery, instruction, and setup of the products are performed solely by and independently of the manufacturer.

    Important Tips

    This humidifier cannot be run off of 12 volt DC power. If a machine is powered by 12 volts, the heated humidifier will not run. A 110 volt pure sine inverter hooked to a 12 volt battery can be used to power an S8 CPAP and this humidifier.

    This humidifier integrates with the full line of ResMed S8 and S8II Series CPAP/APAP/VPAP Machines. The H4i Heated Humidifier is not compatible with:

    • AutoSet CS 2
    • S7 AutoSet Spirit
    • S7 Series
    • VPAP III Series
    • VPAP Malibu

    VPAP III Series is not an S8 model and will only work with the HumidAire 2i Heated Humidifier.

    The S8 AutoSet II and Elite II are compatible with this product, but the CPAP machines were manufactured BEFORE the H4i was manufactured. When setting either machine, please note that H3i will appear on the display.

    Maximum Fill Level Tips

    • Do not fill the water tank above the maximum fill line. Damage to the humidifier or therapy device may occur. If the water tank is overfilled, water may leak out of the tank inlet (located on the back of the tank) when installing the tank lid.
    • When disconnecting the hose from the tank outlet, be careful to ensure that the hose is not holding water. Water could travel through the hose and into the machine.
    • Use only room temperature distilled water in the tank. Do not put any chemicals or additives into the water. Possible airway irritation or damage to the water tank may result.
    • Remove the tank, empty all water, and replace the empty tank before transporting the humidifier base.
    • Do not attempt to fill the water tank while it is inside the humidifier.
    • To avoid spilling, do not disconnect the humidifier from the therapy device with water in the tank. Remove the water tank from the humidifier before disconnecting the therapy device.
    • Do not turn the humidifier on without the water tank installed. The Humidifier number setting must remain on 0 if there is no water in the water tank.
    • The humidifier door must be set in the open position before removing the water tank. Do not remove the water tank without making sure that the humidifier door locks into the open position.
    • Do not move the humidifier while the water tank has water in it.

    Manufacturer Warranty

    This product comes with a 1 Year Manufacturer Warranty. will work with the manufacturer on your behalf if the product needs repairs. Please follow these steps:

    • Contact us at or 1-800-356-5221 to receive an RMA (Return Merchandise Authorization) Number before returning the equipment
    • Include a note with the product describing the issue you are experiencing, along with your full contact information to include a return shipping address and the RMA number provided to you
    • Ship only the defective items to at 10101 Stafford Centre Drive, Stafford, TX 77477
    • Do not return accessory items such as the carry bag, hose or power cords
    • Loaner Humidifiers are available for rental during the warranty process
    • Email updates will be sent to keep you informed as the product moves through the warranty process
    • will contact the manufacturer on your behalf and handle all shipping between us and the manufacturer
    • The repaired or replaced unit will be returned to you. Shipping charges may apply.

    Please note: The manufacturer warranty is voided by water damage or misuse of the machine.

    CPAP Video & FAQ

    Frequently Asked Questions (FAQs)

    Are prescriptions required for mask, machine and/or humidifier purchases?
    Yes. Federal law requires we have a valid prescription on file before we ship your mask, machine and/or humidifier.

    We provide many easy ways to get your prescription:
    • We can request your prescription for you! When you checkout, just let us know you would like us to request your prescription, or you can log into your account to have us request your prescription.
    • Fax your prescription to our toll free fax number: 866.353.2727, or our international fax number: 713.541.7370
    • Email your prescription to
    • Upload your prescription in your account, under the Prescriptions Section
    For more information on prescriptions, please see our Prescription Section of the Learning Center.
    What are the benefits of using a humidifier?
    Many PAP users experience nasal congestion and dryness of the nose and throat during treatment. This can be especially problematic for new users who are adapting to treatment. Humidification adds moisture to the air helping to reduce the symptoms of dryness and congestion.

    Nasal congestion also leads to mouth breathing, which perpetuates the problem of dryness. If this is an issue for you, try a heated humidifier.
    What is a heated humidifier?
    A heated humidifier uses heat to warm the water to add moisture to the airstream. The heat is adjustable for more or less moisture. A heated humidifier water chamber is much smaller than a passover humidifier water chamber.

    In our experience, it is common for CPAP users to report that their therapy is greatly enhanced by the use of a heated humidifier.

    There are three types of heated humidifiers:
    • Stand Alone Humidifiers
    • Integrated Humidifiers
    • Built In Humidifiers
    What is a passover humidifier?
    A passover humidifier uses a chamber of room temperature water with the CPAP to add moisture to the airflow and reduce irritation to the nasal passages.

    Air flows from the CPAP through a short hose to the humidifier chamber where the air "passes over" the water to pick up whatever moisture it can. The air then flows into the six foot hose to the mask.

    Passover humidifiers may provide sufficient moisture with CPAPs set at lower-end pressures. However, if the moisture is not sufficient there is no way to increase the amount of moisture added. The water is room temperature. In cold climates, the water temperature will drop causing the CPAP air to become very cold, and causing the amount of moisture to be reduced.
    What is an integrated humidifier?
    An integrated humidifier is used with a specific CPAP and fits directly onto the machine. For most heated humidifiers, this design eliminates the need for a second hose as well as a second power cord.

    An advantage of an integrated humidifier is that it works very closely with the CPAP machine to deliver humidification. Also, an integrated humidifier is a compact unit that uses fewer parts to provide moisture to the user.

    A disadvantage of the integrated humidifier is the user will receive less moisture when it is used with a passover humidifier. The smaller surface area effects the amount of moisture produced. Also, a integrated humidifier will only function with the CPAP for which it was designed.

    You can see if your machine has an integrated humidifier option by reviewing our Compare Charts.

    An example of an integrated humidifier is the PR System One Heated Humidifier as seen below attached to a machine in the PR System One line. PR System One Heated Humidifier
    What is a built in humidifier?
    A "built in" humidifier is designed as a part of the CPAP machine and cannot be removed or separated from the CPAP machine. As with an integrated humidifier, the design eliminates the need for a second hose or power cord. The water chamber can be removed for cleaning or replacement purposes.

    The advantage of a "built-in" humidifier is its compact shape, which operates on fewer parts. This integrated design helps to ensure optimum moisturized comfort and effectiveness when CPAP therapy and humidification are used together. Also, it allows an option for the humidification to be turned off while the CPAP is blowing.

    A disadvantage is that a built in humidifier may produce less moisture if used as passover because the surface area is typically smaller. Also, since the humidifier is "built in" to the machine, detaching it is not an option. This can be an issue for frequent travelers. Lastly, if the machine or humidifier stops working, the entire unit must be sent in for repair or replacement, not just the component that failed.

    An example of a machine with a built in humidifier is the ICON Auto CPAP Machine with Built In Heated Humidifier and SensAwake as seen below. ICON Auto CPAP Machine with Built In Heated Humidifier and SensAwake
    What is a stand alone humidifier?
    A stand alone humidifier is a component that will work with any CPAP and does not attach directly to the machine. It has its own power cord and a short hose to connect it to the CPAP. Generally it will sit next to the CPAP machine and is slightly larger than an integrated humidifier.

    The advantage of a stand alone humidifier is the fact that it may be used with any CPAP machine.

    The main disadvantages are that the size is often larger than either a "built in" or integrated humidifier and that a short hose is needed to connect it to the CPAP machine.

    An example of a stand alone humidifier is the Fisher & Paykel HC150 Heated Humidifier as seen below. HC150 Heated Humidifier
    How do I care for my humidifier?
    To care for your humidifier simply empty and clean the water tank each morning. Only distilled water should be used in the humidifier to avoid mineral deposit build up. S9 Dishwasher Safe Humidifier Chamber
    What does a humidifier prescription need to say?
    A humidifier prescription must contain all of the following information:
    • One of the following words or phrases: "CPAP Humidifier", "Humidifier", "HH", "CPAP Supplies", "CPAP Mask", "CPAP", "Continuous Positive Airway Pressure", "APAP", "AutoPAP", "AutoSet", "Auto CPAP", "Auto Adjusting CPAP", "Self Adjusting CPAP", "BiPAP", "BiLevel", "VPAP", "BiPAP Auto", "BiPAP ST", "Synchrony ST", "VPAP ST"
    • Your physician's contact information
    • Your physician's signature
    • The patient's full name
    What is rainout?
    Rainout is the accumulation of water in a CPAP tube due to warm moist air cooling and condensing on its way from your CPAP machine to your CPAP mask.

    The image below from Fisher & Paykel explains how rainout is formed. Warm, moist air leaves the heated humidifier and travels through the CPAP tube. As air flows through the tube, the temperature of the room causes the tube to cool. As the tube cools, the air inside releases its moisture, and creates condensation in the hose.

    Solutions to rainout include:
    • Raise the temperature of your bedroom.
    • Keep your CPAP machine at the same level as your bed.
    • Insulate your tubing with a hose cover like Snugglehose.
    • Reduce the tempurature setting on your heated humidifier.
    • Purchase a CPAP machine with a rainout reduction comfort feature.
    • Some machine systems offer a compatible heated CPAP hose which maintains the temperature from the machine all the way to the mask, reducing the occurrence of rainout. The list of available heated hoses can be found here: Hoses With Heating Coils.
    • If your machines uses a standard hose, consider the ComfortLine Heated Tubing Kit.

    Conventional Humidification
    Why do I need to use distilled water with in my humidifier chamber?
    Use distilled water to help keep the humidifier chamber clean and mineral deposit free. Tap water should not be used as it will leave hard white mineral deposits in the chamber as the water evaporates, or it may lead to mold growth. Cases of lung disease have been connected to using contaminated well water in a CPAP humidifier.* Source

    If distilled water is not available where you live, use bottled water. It will be important to clean the chamber each morning, do not leave standing water in the chamber between uses.
    What are the CPAP, BiPAP and Sleep Apnea related HCPCS, CPT or billing codes?
    • A7034 is Nasal Mask
    • A7034 is Nasal Pillow Mask
    • A7030 is Full Face Mask
    • A7027 is Hybrid Mask
    • A7044 is Oral Interface Mask (Oracle)
    • A7035 is Headgear for Mask - Any Style
    • A7036 is Chinstrap - Any Style
    • A7032 is Replacement Nasal Mask Cushion
    • A7033 is Replacement Nasal pillows
    • A7031 is Replacement Full Face Mask Cushion
    • A7028 is Replacement Hybrid Mask Cushion
    • A7029 is Replacement Hybrid Mask Nasal Pillow
    • A7046 is Replacement Humidifier Chamber
    • A7037 is Tubing / Hose - Long & Short Tubes
    • A4604 is Heated Tubing
    • A7038 is Disposable Filter (White / Paper)
    • A7039 is Washable Filter (Gross Particle / Foam/ Black)
    • E0601 NU is CPAP Purchase
    • E0601 NU is APAP Purchase
    • E0470 NU is BiPAP Purchase
    • E0470 NU is BiPAP Auto Purchase
    • E0471 NU is BiPAP ST Purchase
    • E0471 NU is BiPAP Auto SV Purchase
    • E0562 NU is Heated CPAP Humidifier
    • E0561 NU is Passover or Cool CPAP Humidifier
    • E0601 RR is CPAP Rental
    • E0601 NU is APAP Rental
    • E0470 RR is BiPAP Rental
    • E0470 RR is BiPAP Auto Rental
    • E0471 RR is BiPAP ST Rental
    • E0471 RR is BiPAP Auto SV Rental

    E1399 is Miscellaneous and is used for other CPAP items.
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