Hybrid Technology Explained
The “hybrid” water heater design combines the features of both tanked and tankless water heaters. Like the familiar tanked units, the hybrid maintains water pressure across multiple hot water applications, and like its tankless cousins, the hybrid is efficient and can supply continuous flow of hot water on demand.
The defining characteristics of a hybrid water heater are:
Highly efficient stainless steel heat exchanger with large heat transfer area;
Built-in small storage reservoir as part of heat exchanger (typically between three- and eight gallons);
Dual Activation: flow sensing and thermostat control.
Why a hybrid?
The patented hybrid technology was developed as a response to the need for a consistent hot water supply across multiple applications. For instance, a family of six living in a four-bathroom home may all need to shower around the same time in the morning. Their hot water supply needs to last at least two rounds of back-to-back showers.
The familiar gas-fired storage tank can supply hot water to all four showers; however, once the tank runs out it needs time to recover before it can supply hot water again. One way to ensure enough hot water supply is to install multiple tanks in manifold, but this solution is labor intensive, space consuming, and energy inefficient.
Tankless water heaters are space saving solutions that address the seemingly endless hot water supply needs of busy households. However, they work by reducing the flow of cold water through a copper tube heat exchanger, and such flow reduction limits its capacity to supply hot water consistently during colder seasons when a higher temperature rise is required.
Tank heaters operate by constantly maintaining the temperature of water stored in a tank. This method, in which the heater is “standing by” for demand, is inefficient because fuel is used to maintain the water’s temperature even when all the home’s taps are off.
Tankless, or “instantaneous,” water heaters, work on the principle of demand. When a tap is opened with at least a certain amount of water flow, the heat exchanger detects the demand and starts the combustion process.
The hybrid water heater combines technology traits from both tanked and tankless heaters. The combination approach is designed to eliminate general shortcomings of other technologies.
For example, hybrids are activated by either thermostat (similar to tanked) or flow (similar to tankless). One can always be sure that hot water will be supplied regardless of flow.
During low-flow situations, the hybrid behaves like a tank-type heater by having minimum fixed fuel usage and thermostat activation. Although equipped with some storage capacity, the small volume minimizes standby fuel usage. Hybrids also share additional traits with tank-type heaters like a floor-standing installation, standard PVC venting, draining pan, and they can be installed with a recirculation pump for even more efficiency.
During high demand, high-flow situations, hybrid technology behaves more like a tankless heater, with high BTU capacity and full modulation to supply continuous stream of hot water across multiple applications. This gives the hybrid fuel efficiency like the tankless, but with higher flow capacity.
Hybrid water heater vs. tankless water heater gallons per minute ratings can be confusing since they are not based on the same working principle. In fact, GPM and temperature rise should be read with a different mindset when it comes to flow charts and comparing the specifications of the two types.
Tankless heaters have to raise water temperature from cold to hot. The analogy would be to floor the gas pedal in your car in order to accelerate to 60 MPH from dead stop.
Hybrids have small storage tanks that temper incoming cold water. This means hybrids only have to increase water temperature from warm to hot. In situations where a tankless heater is working on a rise of 45 degrees Fahrenheit, the hybrid may be doing just 25 F rise. The analogy would be to accelerate your car to 60 MPH from a running start of 30 MPH.
Certain jobs may be more appropriate for a tank-style heater and other jobs maybe just the thing to make a tankless unit shine. But it’s important for contractors to remember there is now a third choice and that a hybrid may solve all the issues that a homeowner may seem to be having.