the Zonefirst SPRD-18 is compatible with vertical installations

Reliable Pressure Control: Facilitates the frictionless operation required for sensitive pilot-operated systems

but the technical specifications and performance of the 26025B and 26025B/U are identical

To achieve reverse action with this 3-way air valve

As a technical replacement for standard non-vacuum adjustable float-type steam air vents

Watts 0275464 Valve 320734-701 the Zonefirst SPRD-18 is compatibleProfessional grade Watts 0275464, a high capacity Series 174A boiler pressure relief valve, is engineered for critical overpressure protection in large scale hot water heating and domestic supply systems. Constructed with a heavy duty bronze body and a rugged stainless steel spring, this 1 inch NPT valve is factory set to a 150 psi pressure relief setting and delivers a high volume discharge capacity of 3,795,000 BTU hr. The 174A series utilizes a non