Takagi Tankless Water Heater Troubleshooting

Modern tankless water heaters are fitted with PC boards or computer chips to enable them to continuously check their own performance and efficiency. Needless to say, it’s rare to have issues with your Takagi tankless water heater. But, if ever you do, here are common problems and their equivalent solutions.

1. Improper Venting

Never use standard B-vent, which quickly destroys the heat exchanger because of acidic condensation. Always use sealed stainless steel vent pipe approved for all Takagi non-condensing tankless water heaters. Improper venting causes risky exhaust gas leaks.

2. Gas Supply Line Problem

It’s risky to hook up to an existing gas line (normally 1/2 inch diameter). Take note of the gas line requirements as described in the manual. The correct way is sizing for the maximum BTU per hour rating.

3. Improper Gas

The gas and the Takagi tankless water heater must be compatible to each other. Check whether the heater requires natural gas or liquid propane. Buy the heater appropriate for the type of gas supply you have.

4. Temperature/Water Fluctuations

Check input filter for debris and obstruction in case of low flow from the heater. Clean or replace the filter as needed. Before removing the filter, turn off the cold supply and relieve the hot pressure.

In case of insufficient hot water or temperature variations, check the connection between the hot and cold supply of the Takagi tankless water heater. Shut the cold supply and open the relief pressure valve or any hot water faucet. If the hot supply output is steady after the pipe has drained, there is a cross flow problem. Let a plumber fix it. Also, reduce hot water consumption or avoid having too many hote water applications at the same time.

5. Hard Water Problems

Treat the water with softener or de-scaling device when it has high levels of calcium and magnesium. Never use reverse osmosis, which damages the heat exchanger.

6. Dirty Combustion Air

When available combustion air is full of particulate matter enter into the heater, install a direct vent model or kit. Takagi tankless water heater with indirect vent is not ideal in places with polluted air.

7. No Ignition

Provide proper gas pressure to the Takagi tankless water heater. Ensure that the unit is properly grounded and check the fuses. Wiring harness and igniter must be operational. See if the gas valve opens and the flow switch works. Burners must be properly installed and seated. De-clog inlet filter, as well as faucet aerators and shower head.

8. Frozen Heater

Supply electricity and gas to activate freeze protection during winter to prevent the heater from freezing and the heat exchanger from bursting. It also helps to install the auto drain down solenoid valves.

Preventive Measures

It’s a trouble to have a faulty Takagi tankless water heater, particularly when you’re in dire need of hot water. To keep your water heater in top condition, observe regular annual inspection and periodic maintenance.

  • Clean burner, control compartments, filters, and air passages.
  • Check the venting system. The vent exhaust must be free of snow and ice.
  • Observe visual inspection of flame, which should be clean, blue, stable flame evenly distributed on the burner.
  • Flush heat exchanger with de-scaling or water softener.
  • Keep fan and motor clean and free of dirt.

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