Getting Wilo specified: what engineers need to write Wilo into a hydronic pump specification correctly.

The engineers who specify Merion Pump equipment do not always start the conversation by asking what brand we carry. They start by asking what pump meets the application requirements. The specification gets written around performance, efficiency, controls interface, and installation requirements. The manufacturer name follows from the product that best meets those requirements.

Getting Wilo written into commercial hydronic pump specifications requires understanding what Wilo products offer that engineers care about and how to articulate those advantages in the language of a mechanical specification rather than in the language of a sales conversation. This article is written for engineers who are evaluating Wilo for a commercial hydronic application and for facility managers who want to understand what a Wilo specification looks like before they bring it to their engineer.

Why Wilo is worth specifying

Wilo is a German pump manufacturer with a product line that covers circulators, inline pumps, split case pumps, submersible pumps, booster systems, and high-pressure multistage pumps for commercial and industrial applications. In the Pennsylvania, New Jersey, and Delaware territory served by Merion Pump, Wilo products are available across the full range of commercial hydronic applications.

The case for specifying Wilo begins with the efficiency performance of the wet rotor circulator line. The Wilo Stratos series EC motor technology produces significantly lower energy consumption than comparable PSC motor circulators across the full operating range. For engineers designing to energy codes that specify pump efficiency requirements or for owners pursuing LEED certification where pump energy is part of the calculation, the Wilo Stratos efficiency numbers are worth knowing before the specification is written.

The controls integration capability of the Wilo commercial product line is a second specification advantage. BACnet, Modbus, and Wilo Net communication protocols are available across the product line, and the ability to integrate pump operating data into the building automation system is increasingly specified on commercial projects where the owner wants visibility into mechanical system performance beyond the pump’s local display.

How to write Wilo into a specification

A pump specification that references Wilo by name needs to be written with enough technical specificity to justify the named product while remaining defensible if challenged during the bidding process. The most effective approach is to specify the performance and technical requirements that the Wilo product meets and list Wilo as a named product along with the basis of design.

For a Wilo Stratos MAXO circulator in a domestic hot water recirculation application, the specification might read: high-efficiency wet rotor circulator with EC motor, constant temperature control function maintaining supply loop temperature within defined limits, Legionella thermal disinfection detection, stainless steel pump housing, BACnet MS/TP or Modbus RTU communication interface, and maximum operating pressure of 145 PSI. Wilo Stratos MAXO or approved equal.

The approved equal clause requires the bidder to demonstrate that a substituted product meets all specified requirements. A PSC motor circulator is not an approved equal to an EC motor circulator under a specification that requires EC motor technology. A circulator without BACnet capability is not an approved equal under a specification that requires BACnet. The specificity of the specification determines how effectively it holds.

For Wilo booster systems in domestic water pressure applications, the specification should reference the specific pressure zone requirements, the variable speed drive control strategy, the NSF 61 and NSF 372 certifications required for potable water contact, and the communication interface. The MVI multistage pump in a booster configuration covers applications up to 750 GPM and 980 feet of head with NSF 61 and 372 certification and cartridge seal replacement without motor removal.

What engineers need from the Merion team

Engineers writing Wilo into a specification need product submittals that include the performance curves, the efficiency data at the specified operating point, the control system documentation, and the BAS integration protocol documentation. They need the NSF certification documentation for potable water applications. They need dimensional data for equipment room layout. And they need someone who can answer application questions before the specification is finalized rather than after the bid is submitted.

The Merion Pump team provides pre-specification technical support for Wilo applications including selection assistance, efficiency calculations for energy code compliance documentation, and BAS integration guidance. For engineers working on projects in Pennsylvania, New Jersey, and Delaware who are evaluating Wilo for a commercial hydronic application, reach out to the Merion team before the specification section is drafted.

For boiler plant applications where the Wilo pump selection needs to be coordinated with the boiler specification, the GP Energy Products team handles commercial boiler selection across Pennsylvania, New Jersey, Delaware, and Maryland. Visit gpenergyproducts.com for more. For applications where the Wilo pump is part of a factory-assembled packaged system, FabPro Systems handles the packaged system design and can coordinate with Merion on the pump specification. Visit fabprosystems.com for more.

Merion Pump Company represents Wilo across all 67 Pennsylvania counties, New Castle County Delaware, and New Jersey. If you are specifying a commercial hydronic pump system and want to evaluate Wilo before the specification is written, reach out and we will get the right information to you before the deadline.

References
1. Wilo USA. Commercial product documentation including Stratos series, MVI multistage, and booster system specifications and performance data. wilo.com
2. ASHRAE. HVAC Systems and Equipment Handbook, Chapter on Pumps. Covers pump specification requirements, efficiency standards, and controls integration for commercial hydronic applications. ashrae.org
3. ASHRAE Standard 90.1. Energy Standard for Buildings. Covers pump efficiency requirements applicable to commercial hydronic systems. ashrae.org
4. NSF International. NSF/ANSI Standards 61 and 372. Covers certification requirements for pump equipment in potable water contact applications. nsf.org