Tankless Instant Shower Water Heater Troubleshooting Tips

Our tankless water heaters are designed for a very long service life. Actual life expectancy will vary with water quality and use.

Hard water causes serious and expensive damage that leaves behind calcium / mineral deposits referred to as scale. As scale builds, it gradually restricts water flow and decreases the efficiency of these various systems* (water filter, pipes, faucet, heater and etc)

Nothing reduces water heater efficiency more than hard water mineral scale. Accumulating on heating elements, it slowly reduces both heat transfer and water pressure, leading to lower performance, and it may cause premature failure. Preventing mineral scale formation with Descaling agent/Food Grade Citric Acid or White Vinegar ensures your water heater's optimal performance and service life.

If you already know the quality of your water. Installing a non-salt based water conditioner may prolong the life of your unit. We recommends DeScaling water filter to ensure consistent water flow, we recommend periodically checking for and removing any scale and dirt in the faucet aerators and showerheads, and in the filter screen in the unit (as shown below) Depending on water hardness, scale build-up may need to be flushed from the unit every six months to a year.

Maintenance Procedure

Shower water heater has a built in filter screen that should be cleaned from time to time to remove any blockage and sediments deposit.

Clean Stop ValveClean Hand Shower Filter Mesh

In general it is recommended to use Descaling water Filter before connecting the inlet water flow through the system*, as it protects appliances including water heater against any damage caused by scale build up due to minerals found in hard water. 

Recommended - Descaling Filter is to be installed on the cold water inlet of the water heater, where it treats the water entering the water heater. It will provide protection for flow rates up to 6 gallons per minute.

For Shower Water Heaters that already has mineral deposit or scale build up due to hard water or cases where descaling filters are not used. Descaling can be easily done by using Food Grade Citric Acid or White Vinegar (100ml) diluted in water (1 liter) passed through the inlet of Shower water heater to shower head.

Descaling Procedure

Descaling Benefits:

  1. Disconnect the power to your shower water heater.
  2. Close the incoming water flow from the service valve and remove service caps.
  3. Connect the hose to the pump, and other end of the hose to the inlet valve. Place the pump into the bucket 
  4. Pour Food Grade Citric Acid or White Vinegar (100-150ml) diluted in water (1.5 liter) in to a bucket 
  5. Place the Hand shower in the bucket effectively creating a loop from the bucket through the tankless water heater
  6. Plug the pump into grounded receptacle.
  7. Allow the pump to circulate the solution through heater for 30-45 minutes. Unplug pump to stop it.
  8. Disconnect the hose from the pump and remove pump from bucket. Discard the letover solution.
  9. Flush your tankless water heater for 3-5 minutes or until water flows clear by opening the connected inlet valve to allow incoming water to exit through the hand shower 
  10.  Connect power to water heater and return appliance to service.

  1. Protects from harmful hard water scale
  2. Protects manufacturer's warranty coverage
  3. Protects equipment investment
  4. Ensures optimal performance and efficiency
  5. Maintains water pressure and flow rates
  6. Does not add chemicals to the water
  7. Environmentally friendly
  8. No daily maintenance

Troubleshooting Tip


Possible causeSolution
1No hot water but audible click can be heard when water is turned on
  • Power switch OFF
  • Safety thermal cut-out tripped 
  • Power switch ON
  • Reset thermal cut-out
2No hot water and no audible click can be heard when water is turned on
  • water flow too low to activate flow switch
  • clean faucet aerator.
  • open shut-off valve completely.
  • open flow adjustment screw.
  • clean filter screen
3Water not warm/hot enough
  • water flow too high
  • voltage too low
  • reduce water flow
  • supply correct voltage to unit.
4No water coming out from the water heater spray handle ("Heater light is OFF" but "ELCB light is ON")
  • Dirt particles blocking filter at inlet stop valve
  • Interrupted water supply
  • Incoming water supply stop valve, service valve turned off
  • Low water supply to trigger flow switch
  • Malfunctioning on flow switch
  • Remove filter at inlet stop valve and clean (see filter maintenance above)
  • Check whether the water supply is available by taking out inlet stop valve connection and check if water supply is available
  • Turn on stop valve and service valve
  • Heater require min 3 liter per minute or 3 psi to activate flow switch
  • Magnet jammed / dislocated better replace with new part. Reed switch failure better replace new part

If you are not able to resolve a problem please contact / whatsapp us at +91 9959 8399 50  / 9000 9222 57 or email us at support@walkaline.biz before removing the unit from the wall. Walkaline will be happy to provide technical assistance. In most instances, we can resolve the problem over the phone.