Descale Tankless

Tankless Water Heater Descaling Procedure

Another common question we are asked is, “Can I Descale my own tankless water heater?  The answer is YES.  This one is a little more complex but if you’re even a little bit handy, You Can Do It!

You’ll need the following items:

Two gallons of white distilled vinegar.

One five-gallon bucket.

One 1/3 hp sump pump. 

Two washing machine hoses. 

The pictured is a set of tankless water heater service valves.  Before you purchase the necessary supplies for descale make sure you have these valves installed on your tankless water heater.  If you do not, contact us for service valve installation.  If you do, then proceed to descale procedure.

  1. Turn off the LP or Natural gas going to the heater.
  2. Turn off the hot and cold water (side valves pictured)
  3. Unscrew the service port caps and let them hang from their rubber straps.
  4. Attach one washing machine hose to the pump and the other end to the cold service port.
  5. Attach the other hose to the hot service port and the other end back to the bucket.
  6. Turn on service port valves (top valves in the picture)
  7. Let all water in the heater drain into the bucket and discard the water.
  8. Place pump in the bucket and fill with two gallons of white distilled vinegar.  Plug in pump.
  9. Let pump run for an hour. (If you have a Rinnai the alarm will sound, nothing you can do) 
  10. After an hour, unplug the pump and discard the vinegar.
  11. Turn off the cold service valve and remove the pump and hose.  Replace screw cap.
  12. Turn on the cold-water valve (side valve pictured) and allow fresh water to flow through the unit to the bucket.  DO NOT TURN ON THE HOT WATER VALVE (side valve pictured) YET!
  13. Fill bucket three times (dumping when full) to wash the vinegar from the unit.  If you don’t do this step you won’t like the way your coffee tastes. 🤣
  14. Turn off the hot service valve and remove the hose.  Replace screw cap.
  15. Unplug the unit.  Wait 30 seconds then plug it back in.
  16. Turn on the LP or Natural gas valve.  Turn on hot water valve (side valve pictured).  
  17. Run hot water from a faucet in your home to ensure you have hot water.