Fisher and Paykel Healthcare MR850
Fisher and Paykel Healthcare · Model MR850
One button selects optimal temperature and humidity levels for adult, pediatric and neonatal patients. Easy set up with simple controls and an easy to read display. Clinically based alarm system. Advanced algorithms and the ability to sense flow optimises humidification delivery and minimises nuisance alarms. Automatic standby during periods of gas flow interruption or water out.
Typical Failure Modes
Compiled for this model from its own documentation and established engineering knowledge for this equipment class - not from a verified service record. Confirm against the manufacturer's service manual.
Chamber not heating to target humidity / temperature
HighSymptoms: Low airway temperature, condensation or dryness, temperature not reaching set point.
Root cause: Water chamber not seated on the heater plate, a failed heater base plate, or a temperature-probe fault.
Heater-wire circuit alarm
MediumSymptoms: Heater-wire fault alarm, circuit not heating, rain-out in the tube.
Root cause: Open heated breathing circuit, a faulty heater-wire adapter, or (MR730) the F2 fuse.
Temperature probe fault
MediumSymptoms: Implausible temperature, probe-fault alarm, unit will not run.
Root cause: Damaged airway or chamber temperature probe or its connector.
Servo control fault
MediumSymptoms: Unit cannot hold the set gradient, alarms and reverts to fail-safe.
Root cause: Control-board or sensor fault.
Water-out / chamber fault
MediumSymptoms: Chamber runs dry, water-out alarm, auto-feed not maintaining level.
Root cause: Empty supply bag, a stuck float valve, or a cracked chamber.
Serviceable Parts & Consumables
Serviceable items for this model, compiled from its documentation and engineering knowledge for this equipment class. Service class and relative cost are estimates, not manufacturer figures; no part numbers are given. Confirm intervals and pricing against the manufacturer.
Heater base plate
Class Major service partRel. cost $$$R&R Difficult
Temperature probe set (airway + chamber)
Class Frequent wear itemRel. cost $$R&R Easy
Heater-wire adapter
Class Periodic replacementRel. cost $R&R Fairly easy
Water chamber
Single-patient or per-protocol consumable.
Class Frequent wear itemRel. cost $R&R Easy
Auto-feed / float valve assembly
Class Periodic replacementRel. cost $$R&R Moderate
| Part | Service class | Relative cost | R&R difficulty |
|---|---|---|---|
| Heater base plate | Major service part | $$$ | Difficult |
| Temperature probe set (airway + chamber) | Frequent wear item | $$ | Easy |
| Heater-wire adapter | Periodic replacement | $ | Fairly easy |
| Water chamber Single-patient or per-protocol consumable. | Frequent wear item | $ | Easy |
| Auto-feed / float valve assembly | Periodic replacement | $$ | Moderate |
Relative cost: $ lowest · $$$$ highest service-part cost for this equipment class. Not a price.
Troubleshooting Approach
A starting sequence for this model, compiled from its documentation and engineering knowledge for this equipment class. Follow the manufacturer's service documentation for the actual procedure.
Symptom: Not reaching target humidity/temperature
- Confirm the water chamber is fully seated and latched on the heater plate and has water.
- Check the airway and chamber temperature probes and connectors; swap in a known-good probe set.
- Confirm the heated breathing circuit is intact and the heater-wire adapter is connected.
- Check the heater-wire circuit continuity.
- If it still will not heat, replace the heater base plate.
Symptom: Servo / control alarm
- Note the exact code and the multiplexer stage if shown.
- Power-cycle the humidifier.
- Try a known-good probe set to rule out a sensor cause.
- If the code returns, the unit is in fail-safe - remove from service.
- Refer to Fisher & Paykel service with the code.