Paloma Tankless Water Heater 7.4 (PH-28R) Review

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Paloma tankless water heater 7.4 review. PH-28R or 7.4 models are high volume, whole-house units, designed to provide an endless hot water, instantaneous and only when you need it. With the newest gas features and tankless technology implemented, Paloma 7.4 models are high efficient and great performers.

With the respect of venting option and installing location, Paloma 7.4 tankless water heaters are available as:

  • Direct Vent - PH-28R DVSN(P) (P for propane)

  • Indoor models - PH-28R IFSN(P)

  • Outdoor - PH-28R OFN(P)

Technical data

Power and efficiency

Every Paloma tankless water heater from this group is able to work with the maximum gas input of 199,900 BTU/hr and is considered as high efficiency, with the energy factor of 0.82 and thermal efficiency 84%. This is mainly done with a help of the intelligent electronic system, designed also to provide high safety environment for its users.

With a gas modulating valve, PH-28R Paloma tankless water heater adjusts its power, based on the water flow demand and temperature, and it can work in a range from minimum 19,000 to 199,900 BTU.

Temperature settings

Maximum hot water temperature is factory-set on 120 F but it can be adjusted to up to 140 F for residential models.

Capacity and flow rate

With 314 gallons of hot water per hour, Paloma tankless 7.4 models are high volume units, and are able to provide enough hot water for up to three simultaneous showers and supply middle size residential homes.

Use this value as a reference for southern, warmer areas (Sunbelt), where the incoming cold water temperature is 60 F; in northern and colder areas, where incoming water is 40 F and the supply is 5.2 gallons per minute.

In order to start and protect the water heater at the same time, minimum cold water flow has to be met, which is for PH-28R models 0.66 gallons per minute and minimum pressure of 14 psi. At the same time to prevent inner parts from malfunctioning, maximum allowed water pressure is 150 psi. TPR valve, which is must to installed, was designed and tested on that pressure.

Venting Options

PH-28R OFN is the Paloma 7.4 outdoor model that cannot be installed indoors and in any other position except vertical. Due to the negative influence of cold weather and freezing temperatures, recommendation is to protect your tankless water heater, hot and cold water lines with a proper insulation.

PH-28R IFSN (P) is the Paloma tankless water heater for indoor installation only. For the proper work and safety, a proper venting material has to be mounted on the heater, with a termination suitable for Category III venting.

These indoor models are using one-pipe system to discharge flue gases, 4" in diameter, UL approved and Category III stainless steel, while the air for combustion is used from the inside. Fresh air must be supplied through two equal openings properly sized, either from the outside or other room. Venting pipes can be run horizontally or vertically and with an adequate termination.

emergency plumber

Recommendation is to install a vent with a slight downward slope of horizontal run toward the outside so the formed condensate can securely leave the unit. If the downward slope is not possible, or the pipe is run vertically, than condensate trap has to be installed.

As these tankless models are installed indoor, there is always potential hazard of carbon monoxide leak. That is why Paloma is using an exclusive sensing burner and ICAD safety system not only to optimize combustion and make the unit greener, but to shut the water heater down in case of raised level of carbon monoxide.

Paloma direct vent water heaters, PH-28R DVSN, must be installed with a 2/4" diameter, UL approved and Category III coaxial stainless steel vent pipe, horizontally or vertically run and with a proper termination.

Features and Benefits

paloma tankless water heater Paloma tankless water heater 7.4 can be connected with another residential gas unit to gain even more power, by using DUOnex Cable that has to be purchased separately. Combining its power, the First Hour hot water supply will reach amazing 516 gallons, while 100 gallon tank type will have only 135 gallons max.

The ignition device automatically lights the burner and eliminates the need for pilot light and energy waste. It is very easy to use, and together with built-in electric blower contributes in rising the thermal efficiency.

Paloma tankless water heater brings also computerized self diagnostic program and error code display, which helps in troubleshooting and repairs.

Using the manual and error code on the unit; like 11, 12, 15, you can define what is the possible cause (valve is not open, low water flow, low gas pressure...) and how to repair it (open the faucet to increase the flow, or call the service).

Other benefits and safety features can also be found in the article about Paloma water heating here.

You can buy Paloma tankless water heater from 7.4 series online at or and check the reviews also) from $900 or in Home Depot both Canada and US. Keep in mind that 7.4 series qualifies for the 2009 Federal Tankless Tax Credit as it is Ene    yStar rated.


Direct Vent - PH-28R DVSN(P)

Indoor PH-28R IFSN(P) and Outdoor PH-28R OFN(P)

(Pictures courtesy of Paloma)