Replacement Water Chamber for Luna Heated Humidifier 3B Medical Sale! from $ 26.50 Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. If you are interested in a quote for expedited shipping, contact us at 844-757-9355 or email us at firstname.lastname@example.org Replacement water chamber for Luna CPAP and APAP heated humidifiers. Recommended replacement schedule: every 6 months.