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. 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. 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. 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. 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.1. Improper Venting
2. Gas Supply Line Problem
3. Improper Gas
4. Temperature/Water Fluctuations
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.
About Tankless Water Heaters by Takagi
A significant advantage of Takagi over other brands of tankless hot water heaters is their universal applicability. Besides typical domestic hot water heating application, these heaters can be used for baseboard/radiator heating, radiant floor heating and even snow melting applications. All Takagi units can be divided according to the fuel type (natural gas or propane), installation type (indoor or outdoor) and application (residential or commercial). The fuel type is denoted by the “-NG” or “-LP” at the end of the part#; indoor/outdoor installation type is denoted with “-IN” or “OS” suffix respectively.
Takagi tankless water heaters are packed with safety features such as freeze, overheat, and surge protection, and offer easy troubleshooting using the external temperature controller. Residential models T-H3 series are Energy Star rated.
Takagi offers a limited 12-year warranty for heat exchanger and 5-year warranty for parts on all residential models and 5-year/5-year for commercial.
Takagi Tankless Series
Takagi T-KJr2
The T-KJr2 series is the smallest water heater in Takagi line with an energy factor of 0.82, designed mostly for 1-2 bathroom applications. This series replaces the older Takagi Jr models.
Takagi T-K4
T-K4 heaters replace older Takagi T-K3 and T-K2 series and are capable of providing hot water in 2-3 bathrooms depending on the climate. Energy factor is 0.82.
Takagi T-D2
T-D2 series are a step above the T-K4 models, capable of delivering hot water for up to 4 bathrooms in warmer climate. They feature a commercial grade copper heat exchanger and Easy-Link connectivity. Energy factor is 0.82.
Takagi T-H3
T-H3J, T-H3S and T-H3 series are high-end condensing tankless water heaters with PVC venting capability, Easy-Link connectivity, Multi-Link compatibility (connect up to 20 units), commercial grade copper primary heat exchanger and 316L stainless steel secondary heat exchanger. The units boast an energy factor of 0.95 and have a hot water output similar to that of the T-KJr2, T-K4 and T-D2 respectively.
Takagi T-M32 and T-M50
T-M32 and T-M50 are NSF certified commercial water heaters with Easy-Link and Multi-Link features and a superior HRS35 copper alloy heat exchanger coil (C1220 alloy for ASME series).
Sizing
For residential domestic hot water heating applications,
there are several sizing options available. Brochure/Product Guide on each product page lists a model by model comparison with suggestions based on climate and number of bathrooms for easy selection. The second, more precise option, requires calculating hot water output of the unit in GPM (gallons per minute) using the temperature rise table (listed in the same file mentioned above). When unsure about the climate, use the second option or select a larger size model.
For commercial
applications, always use the second option to calculate the total required hot water output in GPM based on the temperature rise (difference between municipal/ground water temperature and desired output temperature). For larger applications, several tankless units may be required.
Venting
All Takagi tankless water heaters, with exception of the T-H3 series (incl. T-H3J and T-H3S) require 4” size, Category III stainless steel venting (5” for commercial). All typical venting parts
(pipes, elbows, collars, adapters, etc.) can be found on the Parts & Accessories page.
Takagi T-H3 series are condensing models which allow using Schedule 40 PVC, CPVC or PP pipe instead of the Cat. III.
The venting pipe sizes and maximum allowed pipe run are model-specific and are shown in the installation manual.
Air intake on all outdoor models is built-in. For indoor models, fresh air supply is taken from indoors by default. To convert to outdoor air intake, a TK-TV10 adapter
is used. Given typical installation where water heater is mounted on an outside wall and vented though it, the best option for outdoor intake and exhaust is 2SVSHTC43S, for indoor air intake, 2ZVWB04.