Tankless water heaters operate on a fundamentally different thermal principle than storage tank units, and understanding that difference matters when deciding whether a tankless system is the right fit for a particular home. Long Beach Pro Plumbing Inc installs and services gas and electric tankless water heaters throughout Long Beach, and we give homeowners a realistic picture of both the benefits and the installation requirements before any commitment is made.
A condensing tankless unit, which represents the current high-efficiency tier of residential gas water heaters, achieves uniform energy factors of 0.90 to 0.96 by extracting heat from the combustion gases as they cool below the dew point of water vapor. The secondary heat exchanger captures the latent heat of vaporization as combustion gases condense, which is where the efficiency gains come from relative to conventional non-condensing tankless units. Condensing units require a drain for the condensate, which is slightly acidic and must be properly handled.
Flow activation in a tankless unit occurs when a flow sensor detects a minimum flow rate, typically 0.5 to 0.75 gallons per minute depending on the model. Below that threshold, the burner does not ignite. This means very low flow demands, like a barely open hot water tap, may not trigger the unit. The igniter and gas valve modulate burner output across a wide range to match the thermal load, which is why tankless units can maintain a set output temperature across varying flow rates.
Gas line sizing is the most commonly underestimated aspect of tankless installation in Long Beach. A single high-capacity residential tankless unit may require gas supply at 199,000 BTU/hr, compared to 36,000 to 50,000 BTU/hr for a standard tank water heater. Existing three-quarter inch gas lines that served a tank unit are often undersized for a tankless unit if the run from the meter is more than 20 to 30 feet. We calculate the available BTU capacity of the existing supply line using pressure drop calculations before confirming that the line can support the proposed unit.
Venting for non-condensing tankless units requires Category III stainless steel vent pipe rated for the higher flue temperatures produced by the heat exchanger. Condensing units can typically use CPVC or polypropylene vent material due to the lower exhaust temperatures. Both types can use direct vent concentric pipe that draws combustion air from outside and exhausts through the same penetration, which is the preferred configuration for Long Beach homes where indoor air sealing is a concern.