Monitor MWH180EX Gas Fired Tankless Water Heater

The MWH180EX tankless water heater is designed for installation outside of the home. On-demand tankless gas water heaters provide a continuous supply of hot water at published flow rates with a preset temperature of 120°F, cutting water heating costs up to 50%. The compact design of the MWH180EX tankless water heater allows for installation virtually anywhere.

The MWH180EX has a maximum water capacity of 5.8 gallons per minute at a 54°F temperature rise which allows you to use hot water at up to three plumbing fixtures simultaneously. An additional remote control for enhanced performance is available. To protect the MWH180EX from severe weather conditions a recess box (RB-100) is available.


  • Built-in signal notifies the microprocessor to start the burner operation when the faucet is open and to stop when closed
  • Energy efficient electronic ignition system grants significant savings in energy and money
  • Advanced control system uses a sensor to maintain a constant outgoing water temperature
  • For added safety the microprocessor limits the maximum temperature of the hot water to 120°F when not using the remote control
  • Service codes are displayed on a remote control specifying diagnostics during maintenance calls
  • Designed to prevent varying temperature of hot water when the faucet is cycled on and off, quick response mode for rapid heating
  • 10 year warranty for the heat exchanger and one year reasonable labor


Dimensions (HxWxD) 22 5/8 x 13 25/32 x 6 1/2
Weight 40 lbs
Maximum gas input rate
180,000 BTU/h
Minimum gas input rate 20,000 BTU/h
Hot water capacity range 0.58 – 5.8 GPM
Maximum hot water capacity (54°F rise) 5.8 GPM
Temperature range (with remote) 96°F – 140°F
Maximum water supply pressure 150 psi
Minimum water supply pressure 15 psi
Noise level 49 dB
Connection - Gas 3/4″ MNPT
Connection - Water inlet 3/4″ MNPT
Connection - Hot water outlet 3/4″ MNPT
Electric consumption - Normal 58 W
Electric consumption - Standby 3.7 W
Electric consumption - Anti-frost operation 84 W
Included accessory Remote control

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