Troubleshooting & Repair

Takagi tankless heaters have proven themselves to be highly reliable over the years, requiring little maintenance or repair. However, a few minor service requirements should be performed at least once a year to insure trouble-free performance. These are outlined in your Service and Installation Manual under “Maintenance and Service.” Or call us at 1-888-882-5244.

Takagi Tankless Water HeatersExternal Troubleshooting

A very high percentage of service problems requiring troubleshooting can usually be traced to causes external to the unit. These problems in order of occurrence are:

Improper Venting: The most common error is the use of standard B-vent, which can quickly destroy the heat exchanger due to acidic condensation. Improper venting may cause exhaust gas leaks and would be considered unsafe. All Takagi non-condensing tankless water heaters must use sealed stainless steel vent pipe approved for use in Category III appliances. All Takagi condensing models may use Schedule 40 PVC, ABS pipes, or Category III stainless steel.
Gas Supply Line Problems: Undersized Line: There is a great tendency to just “hook up to the existing gas line,” which is usually only ½ inch diameter. Strict attention must be paid to the gas-line requirements section in the installation manual. Make sure that you size for the maximum BTU per hour rating and not the minimum.
Make sure that you order the correct heater for the type of gas you will be using, Natural Gas or Liquid Propane.
Water Flow/Temperature Fluctuation Problems: If there is a low flow from the heater, the first thing to check would be the input filter. Turn off the cold supply, relieve the hot pressure and remove the filter to check for debris. Clean or replace the filter and then check the flow again. If there is inadequate hot water or variations in temperature, check for plumbing “cross flow,” which means there is a connection somewhere between hot and cold. This may be as inconspicuous as a worn seal in a single-handle faucet. To check for this, shut off the cold supply to the heater and open either the pressure relief valve or any hot-water faucet. If there is a steady flow of water from the hot output after the pipe has drained, there is a cross flow somewhere in the plumbing that must be fixed.
Other causes of temperature fluctuations can be the gas line may be too small, or the heater temperature may be set too high in an effort to “get more hot water.” This can cause a shower to be turned too far to the cold side, which doesn’t allow enough hot-water flow to keep the heater on steadily. In most circumstances, the heater should be set to its default of 122°F.
Hard Water Problems: In areas where the water is very hard with high levels of calcium and magnesium (about 7+ grains per gallon on residential application), Takagi recommends that the water be treated with a water softener or some other de-scaling device. Do not use a reverse osmosis process! It will destroy the heat exchanger. Removing minerals or keeping them in suspension will greatly lengthen the life of the heater and reduce service problems.
Environmental Issues: The heaters should be installed in relatively clean areas with access to sufficient combustion air that is free from dust, lint, grease, or chemicals. If any of these conditions are present, a direct vent model or kit should be installed. For this reason, restaurant, beauty salon and industrial applications should always get a direct vent unit, which draws its combustion air from the outside.

Takagi Tankless Water HeatersInternal Troubleshooting and Repair

Internal troubleshooting is recommended to be performed by professional service providers. Checking internal component should be done only after all of the above external criteria has been thoroughly checked and repaired. Please refer to the Installation Manual or call us at 888-882-5244.