Figure Number: Hydraulic Separators
The Niles Steel Tank Hydraulic Separator is designed to help reduce short cycling of a boiler system and separate building and boiler circulation. The NST Hydraulic Separator uses stored boiler water to buﬀer the system load when the boiler is producing more BTU’s than what the building can handle. When the building has a minimal demand, it pulls from the tank allowing the boiler to “rest”. The Hydraulic Separator is piped so the building ﬂow is separate from the boiler ﬂow, allowing independent circulation.
The Hydraulic Separator acts as a decoupler allowing independent circulation in both building and boiler loops. When the building’s hydronic system has a demand for heat, the buildings circulation pumps pull from the hydraulic separator (ﬁg A.) until there is enough temperature drop in the tank to activate the boiler. When this occurs both boiler and buildings circulation pumps are activated allowing direct ﬂow through the tank (Fig. B ). As the building demand is satisﬁed and it’s circulation pumps are stopped, there is still a demand in the tank to return it to it’s operating temperature (Fig. C ) . The boiler will continue to circulate and ﬁre until the tanks temperature is satisﬁed.
120 to 860 gallons Larger sizes available
ASME Sec. VIII, Div 1 125 psi Bare tank 5 year warranty 4” base ring
The Niles Steel Tank Hydraulic Separators are designed for 125 psi (150 optional). Standard sizes range from 120 gallon up to 860 actual gallons. Custom sizes and additional ﬁttings are available. To properly size the capacity of the Hydraulic Separator, 4 variables are needed: The minimum “run time” of the boiler. Check with your boiler equipment manufacturer for their recommended minimum run time. The minimum BTU output (BTU/hr). The minimum BTU output is based on the boiler output at the minimum ﬁring rate, if equipped with a variable input system that modulates the ﬁring rate down as the demand decreases. The minimum system (heat) load (BTU/hr). Based on the smallest zone calling for heat. Tank delta T for allowable temperature rise. For hydronic heating systems typically allow between 10 and 40 degree rise in tank temperature. V = Tank volume T = Min. boiler run time MBO = Minimum Boiler Output (btu/ hr) MHL = Minimum Heat Load Delta T = Tank temp rise (degrees F)