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How do you fix rinnai tankless water heater code 79

I understand code 79 is an internal water leak. We had a major rainstorm yesterday, so I'm guessing water got into the air vent. This is a brand new house, so there's little chance it's anything else. What's the fix for this? Do I need to just let it dry out, or am I going to need to spend $500 for a plumber to come out on the weekend to fix it?

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  • Barry Zatkalik
    Barry Zatkalik Dec 07, 2013

    Hey bulldog what was the final outcome of your error code 79

  • gary
    gary Jun 27, 2014

    How to fix Code 79. Open up the

  • gary
    gary Jun 27, 2014

    Code 79..(leak sensor detected leak). Open up the cover of the unit by

  • gary
    gary Jun 27, 2014

    Sorry..stupid typing..Ok here we go now...Code 79 fix..First and most important. UNPLUG THE POWER CORD. Open up the unit by removing the 2 gray trim strips. 1 on each side(they pop right off). Remove the 4 phillips head screws holding the cover on. Look toward the bottom of the unit. You will see a small white plastic surface mounted piece with a white wire coming off of it. Thats the leak sensor. When activated it will present a code 79 and shut the unit down not allowing any water to flow through it or flame to ignite. If there is water present around it then find out what caused the water? Was it just a big rain storm? Condensate present? Or do you actually have a leak in the tank somehwere. Most likely it was caused by condensation and/or rain. If thats the case your in luck. Take a small compressor and blow/dry the water off. Plug the unit back in and run some water on the hot side of a faucet. It should be fixed now. Replace your cover and your done. If there was no water present then most likely you have a bad leak sensor. No problem...Theres a quick fix until you can get a new leak sensor and replace it. Follow the white wire coming from the sensor. You will see a disconnect (wire harness) half way up the wire. Unclip it so your now breaking that electrical circuit. That bypasses the switch and tells the unit everything is fine. After unclipping it, plug the unit back in. Run water on the hot side of a fixture and it should fire right up. Replace your cover and order a new leak sensor. Replacing it is simiple as you can see it's only held in by 1 screw..Hope this helps ya.

  • Bulldog9816 Jun 29, 2014

    Unplugged the unit and let it dry out for a couple of days to let the water around the leak sensor evaporate, then restart. It's worked like a charm ever since.

  • Bulldog9816 Jun 29, 2014

    Unplugged the unit for a couple of days of cold showers, and let the lead sensor dry out. It's worked like a charm ever since.

  • Bulldog9816 Jun 29, 2014

    Unplugged the unit for a couplke of days (cold showers during that time!), and let the leak sensor dry out. It's worked like a charm ever since.

  • Anonymous May 02, 2017

    Take front cover off in bottom right there will be a little water use toilet paper or straw remove water plug in and use. reason water got in mine sidewase rain came in vent pipe. option 2 drill little hole to let water out.

  • Jay Ward
    Jay Ward Jul 15, 2017

    Gary, you are the MAN!! Just unplugged the sensor & my water heater is working again!! Thanks!!!



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  • Rinnai Master
  • 5,245 Answers

Do not spend 500 on plumber to determine that condensate drain was not installed properly on vent line, and that acidic water from combustion by-product has been dripping down into tankless and burning hole through the special-alloy heat exchanger instead of going down into floor drain and corroding your plumbing pipes.
Do not spend hours fulfilling the required monthly and yearly maintenance, or spend money on service call each year to get the burner cleaned and gas pressure checked on your tankless computer that heats water...
Instead, fix any tankless problem, any brand tankless, same day do-it-yourself for $385, by replacing 1 part: the whole thing:
Do not install tankless.

Posted on Jul 21, 2013


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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
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SOURCE: Paloma tankless, gas, water heater, error code C7 76

If you look on the left hand side of the burner control module you'll see 4 capacitors - the capacitors have most likely failed...pretty sure anything code 76 is P/S failure. It may also be covered for manufactures defects. If the cap is blown..the top will be slightly raised as apposed to flat like the other nearby caps - they are called top blow capacitors...the damage should be evident.

Posted on Nov 01, 2009

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SOURCE: vinegar flush

You should not have to flush unless the code LC comes up. but here is the flushing diagram.

Posted on Aug 01, 2009

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SOURCE: Rinnai tankless water heater code 12

12 - Flame Failure or Poor Ground

1. Immediate code 12 is usually a defective gas valve, power supply problem, or defective fan motor wiring harness.

2. If code 12 occurs after a few seconds it indicates that proper operation was established, but then stopped unexpectedly.

3. Verify that fuel is being supplied to the unit.

4. Check for proper electrical ground. Unit must use a grounded power supply.

5. Check for flue blockage on inlet or exhaust.

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SOURCE: Loud blower on my new Rheem Power Vent 2 water heater

find out if it does the same noise with the venting disconnected

Posted on Jan 16, 2010

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SOURCE: Rheem Power Vent 2 water heater is flashing 4

The flashing light is a trouble sequence light. Find your manual to see what 4 flashes means. It's usually attached to the side of the water heater tank. Try a quick fix by unplugging the power vent and see what happens.

Posted on May 15, 2010

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