John Wood Tankless Water Heaters
Review and Buying Tips

John Wood tankless water heater

Consider the following facts and tips when selecting the best John Wood tankless water heaters for on-demand heating of potable water in residential and light commercial applications.

The article reviews the top features and benefits of the combined on-demand and condensing technology.

Top features and benefits

High efficiency

All the John Wood water heaters designed for on-demand water heating are using Takagi technology. Models that utilize the condensing technology are ultra-efficient models and as opposing to the non-condensing, they come with the two heat exchangers; one made of commercial grade copper and second made of the stainless steel, resulting in the units’ resistance to the aggressive water action.

Such a combination allows the usage of the latent heat from the flue gases for the high thermal efficiency of over 90%, resulting in great energy and water savings. Non-condensing series consists of the conventional models that are able to provide an energy factor of 0.82 and 0.83.

Flexible venting

With the higher thermal efficiency, especially those models with the energy factor in the range from 0.91 to 0.95, water heating costs are significantly reduced. Also, the products of combustion have the lower temperature, which allows venting with the approved PVC, CPVC, and PP pipes, for added flexibility and lower costs.

The venting system is flexible as it can be installed as the two-pipe system or coaxial direct vent, horizontally or vertically.

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Fast hot water delivery

For homes where the higher demand is needed for the stable temperature and fast delivery, you can use the FlowTHRU storage tank that is specifically designed to work with John Wood tankless water heaters for added comfort.

For the supplemental heating, FlowTHRU storage tanks are equipped with one electric heating element, an adjustable thermostat and side connection for the circulation pump.

Advanced electronics

The condensing water heaters feature the advanced electronics that provide an easy temperature adjustment right on the built-in screen, systems that help in preventing the scalding burns, and the internal freeze protection system.

All the condensing units come with the self-diagnostic system for safety and your convenience. The integrated controller allows you not only to change and monitor the temperature of the hot water but check other parameters and also error codes if the problem exists. On non-condensing units, the error code will show up on the remote controller and computer board.

Feature highlights

  • Warranty - 12 years.
  • Direct venting with the sealed combustion for indoor models available.
  • The exhaust vent pipe length is up to 100 ft.
  • Convenient automatic ignition.
  • Safety: thermistor and hi-limit switch for the exhaust gas, freeze protection...
  • Some models use Easy-link up to 4 units without multi-unit controller (510 and 540 H models only).
  • Multi-Link connects up to 20 units into one system, so the power can modulate from 13,000 to 4.0 million Btu/hr.
  • 240, 340 and 540 series are condensing models.
  • Ultra Low NOx models are available.
  • Recirculation pump control mode available on 510 water heaters.
  • Temperature adjustment from 100 to 140 F, or 100 to 185 F on 540 H models.


Model/Features BTU
# of
JWT-240H-N 15,000
0.95 6.6 99
2 Yes
JWT-320H-N 13,000
0.91 8.0 99
3 Yes
JWT-340H-N 15,000
0.95 8.0 99
3 Yes
JWT-520H-N 10,300
0.91 9.0 99
4 Yes
JWT-540H-N 15,200
0.96 10.0 99
4 Yes
JWT-110-N 19,500
0.82 6.0 99
2 Yes
JWT-310-N 11,000
0.82 8.0 99
3 Yes
JWT-510-N 11,000
0.82 10.0 99
4 Yes

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