John Wood
Tankless Water Heaters
Review and Buying Tips

How to select the best John Wood tankless water heater for home use? Condensing or standard type?

John Wood tankless water heaters

John Wood tankless heating appliances are designed for almost any home or light commercial application, from point-of-use service to whole-house water heating. These small, compact, and wall-hanging units are recommended for households with a high demand for hot water, with larger families and homes lacking the living space.

Even the largest model, with the size of approximately 22”x18”x11” and weight of 59 pounds, is easier to carry and install than the cylinder type. Non-condensing units are even lighter than condensing types.

Model type

The selection of John Wood tankless water heaters is not as extensive as from Rinnai or Noritz manufacturer. The heaters are available as non-condensing from series 110, 310, and 510, and condensing type, series 240, 340, and 540, all built for indoor installation.


Efficient work

Non-condensing type of John Wood water heaters comes from the JWT-110, JWT-310, and JWT-510 series; all utilize the conventional on-demand technology to provide a continuous and endless supply of hot water.

The heaters can use either natural gas or propane and provide the maximum energy factor of up to 0.83, which also meets the Energy Star requirements.

The main characteristics of non-condensing tankless units are one heat exchanger and the temperature controller that digitally displays the temperature and error codes.

Temperature control

The temperature controller TK-RE02 allows temperature adjustment from the minimum 99 F to maximum 167 F or from 113 F to 140 F when changing the dipswitch position. JWT-510 is slightly different from the other two models; it uses the TM-RE30 that allows temperature change from 99 F to 185 F, and up to 4 units can be installed into one system when using the Easy-Link system.


The 510 water heaters have an option to use the recirculation pump, which helps in energy conservation. This is the only unit from this group recommended for commercial applications.

Similar model to buy: Rinnai RUR98


Those models that utilize the power vent design require vents from Category III and are made of stainless steel. These gas appliances can also be converted to direct-vent type with the sealed combustion, and only when using the John Wood conversion kit.


John Wood tankless water heaters from the 240H, 340H, and 540H series come with the condensing technology that requires two heat exchangers. One heat exchanger is made of commercial-grade copper (the primary unit) and secondary made of stainless steel and used to extract the latent heat from flue gases and preheat the incoming water. This is what provides the high energy factor of 0.95, which brings more savings to you and Energy Star compliance. The secondary HE must be made of high-quality material as it deals with the flue gases, which are in acidic conditions and can corrode the element and shorten its lifetime.


The condensing and tankless water heaters are direct vent units, and direct venting makes the installation easy and safe as the surrounding air is untouched. They can use the PVC, CPVC, or PP venting with the Category IV stainless steel pipe.

Built-in temperature control

At the front panel, you will find the built-in temperature and error display for easy control and simple troubleshooting.


The system is fully modulating, allowing the system to work in the power range from 11,000 to 199,000 BTU and with the temperatures from the minimum 100 F to the maximum 185 F.

There are 9 settings available for 240H and 340H models, from 100 F to 140 F and 16 settings for 540H, or from 100 F to 185 F.

Easy Link system

Only the model 540H unit can extend its power and be used in large homes with high water flow because it utilizes the Easy-Link system that links up to 4 units, or when using the multi-link, it connects up to 20 units, but only with the controller. With the 20 units connected into one system, the system will produce up to 4.0 million BTU and still modulate to its minimum power of 15,000 BTU.

Safety features

  • Air fuel ratio sensor (AFR)
  • Exhaust and water temperature sensors
  • Overheat Cutoff Fuse
  • Freeze protection
  • Internal freeze protection

John Wood tankless water heaters from the condensing category can be used in residential and commercial applications for heating potable water and space heating (510, 240, 340, and 540 models).

The warranty is extended - 15 years on the heat exchanger in residential applications, 10 years in commercial, and 5 years on other parts.


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