How to fix frozen boiler pipes in Winter


A couple days before Christmas I had the serviceman come to my apartment. After his inspection he concluded it’s frozen!

How to know if its frozen?

If you see the following error codes: : #15, #16, or #56 it means one or more of your pipes are frozen. (RINNAI BOILER)

How to fix?

  1. Remove the insulation. Usually there is some kind of tape wrapped around it. In my case there was blue tape that I cut and removed.
  2. Slower Method: I used a space heater and placed it facing the frozen pipe. I did this for 6 hours and most of the pipes defrosted. I monitored it every 1 hour or so to test if things were working so the length of time will definitely vary.
  3. Faster method: After six hours I noticed the boiler would turn on / off so I figured some parts wasn’t fully defrosted so I used a Hairdryer and it took about an hour as I focused on the areas which were cold.
  4. Testing: Plug in only the boiler after you think it’s been completely defrosted / melted.
  5. If you hear it running then let it run first for 5 minutes before turning on the boiler thermostat. If you turn on the thermostat the same time as plugging in the boiler it may lead to the boiler producing an error code as it did for me.
  6. After 5 minutes turn on the boiler thermostat and set it to your desired heating
  7. Turn on hot water after 5 minutes.

Note: Make sure to carefully put back the insulation for the pipes after you are done or it will freeze again!

Troubleshooting: (reddit)

  • Do you still have floor heating? Ondol function working? = your boiler is fine.
  • if you are getting hot water in any taps “TURN IT ON FULLY” to get full normal flow established.
  • if you arent getting any hot water from the bathroom shower or sink then the hot water line is frozen to the bathroom from where it branches off from the the line that goes to the kitchen. (do you have cold water in the bathroom still? it would not be strange if you do.)
  • put a space heater in your bathroom to see if that helps thaw pipes.
  • dont let this situation get any worse. keep the boiler going for a hot/warm floor and check/keep all other taps running once in a while: toilet, shower cold, bath cold, kitchen cold and kitchen hot.

Here is a link below to prevent future pipes from freezing!


Korean-Canadian. Living in Seoul, Korea.

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