Paloma Legacy series is a group of tankless water heaters that are very simple by design, used for the indoor and whole house water heating. Legacy models are wall mounted gas appliances that are produced in three sizes, Paloma PH6, PH12 and PH24.
The smallest PH6 units are perfect for hot water heating applications within cottages, cabins or small offices. PH12 are recommended for the average home size and PH24 for large residential homes and even commercial use.
All Legacy models are different (or less sophisticated) from previously reviewed Digital 5.3, 6.6 and 7.4 tankless models, when the design, venting installation options, available features and parts are taken into account.
Paloma Legacy water heaters are using B type, galvanized atmospheric vent, 4", 5" and 7" in diameter, as the cheaper solution than the direct vent systems and its stainless steel vents. Venting system will involve a long vertical vent run.
They are ideal for homes where the water pressure is low, usually under 40 psi and if the electric power is a problem or unavailable.
Also, in order to start heating, minimum water flow has to be reached which is 0.6 gallons per minute for PH6, 0.48 gpm for PH12M and 0.52 for PH24M models; while minimum incoming pressures are 2.1 psi for PH12, 2.4 psi for PH24M and 4.3 psi for PH6.
The largest Paloma Legacy model is PH24M and it provides a maximum supply of 6.5 gallons per minute, or up to 264 gallons per hour (with 64 F rise). This is assumed for southern, warmer areas (Sunbelt), where incoming cold water temperature is 60 F; while in northern and colder regions, where incoming water is 40 F and the supply is around 4.4 gallons per minute.Paloma tankless water heaters PH24M models thanks to the modulating unit provide between 37,000 and max of 178,500 BTU/hr gas input, PH12M unit works with the gas input range between 30,000 and 89,300 BTU/hr, while PH6 has a constant gas input of 43,800 BTU/hr.
This is done by using the mechanical modulation in order to keep the temperature consistent when you change the flow at the faucet.
PH6 model doesn't use modulation to adjust the power when the water flow changes, it remains constant. Since the gas burner has only one stage, heater temperature is adjustable by the volume of water flow that passes through the heater.
Hot water temperature is controlled manually, on the unit, by using the temperature adjusting spindle. The temperature is controlled with this warm/hot knob so you can set the temperature between 60 and 100 F above incoming cold water. Bath controller and the Main controller are not available for Legacy Paloma tankless water heaters.
Paloma Legacy models use a standing pilot light and built-in piezo igniter to light the pilot flame and the main burner. Within this assembly is a thermocouple, a safety element that informs the magnetic safety gas valve to stop the gas delivery when the pilot light is extinguished.
Even with simplified technology and pilot flame, Legacy water heaters are energy efficient units with 80% thermal efficiency, but they are not EnergyStar qualified.
Safety features that these heaters are using to protect the system are:
Overheat limiting device installed on the heat exchanger
Temperature limiting device automatically shuts off the gas to the main burner and the pilot light when the temperature exceeds 194 F.
Magnetic safety valve
You can buy Paloma Legacy tankless water heaters from $550 to $1400 for the largest PH24M model. Paloma provides 5-year limited warranty on heat exchanger and 3 years on other parts.
(Pictures courtesy of Paloma)