Multistack LLC

Multistack LLC, a Wisconsin-based HVAC equipment manufacturer and service provider, competes as a prime contractor in full-and-open federal markets, delivering modular chillers, compressors, heat exchangers, controllers, sensors, and preventive maintenance and repair services predominantly to the Department of State's overseas diplomatic facilities. The company operates with minimal subcontracting exposure (99% of awards are prime contracts) and does not pursue set-aside designations; all 590 awards in the source data carry no set-aside designation across a 22-year federal footprint dating to 2004.

Multistack is a for-profit limited liability partnership headquartered in Sparta, Wisconsin, with a named subsidiary Multistack BAC LLC. The company's primary NAICS code is 333415 (Air-Conditioning and Warm Air Heating Equipment Manufacturing), supported by secondary categories in commercial refrigeration contracting and HVAC component wholesale. Concrete work spans chiller parts supply, preventive maintenance contracts, emergency repairs, and equipment installations at overseas missions. Representative recent prime awards include a $301,274 definitive contract from the Bureau of Overseas Building Operations for preventive maintenance on chancery chillers in Mauritania (September 2026), a $295,768 firm fixed-price contract with the same bureau for chiller and air-handling-unit maintenance at the U.S. Embassy in Pakistan (September 2026, with four one-year option periods), and a $163,025 annual maintenance contract for mission and PCC chillers in Switzerland through December 2027 (May 2023). The company also delivered a $413,680 definitive contract for multistack chillers, hydronic systems, and air-handling-unit service (June 2023).

Customer concentration is extreme: the Department of State Bureau of Overseas Building Operations accounts for 484 awards (92% of award count) and $20.3 million in combined potential value (76% of the total $26.7 million portfolio). The top five funding agencies cover 92 percent of awards by count, with the Bureau of Overseas Building Operations dominating both dimensions. Secondary State Department customers include the Bureau of East Asian and Pacific Affairs (19 awards, $368 thousand), the Bureau of African Affairs (8 awards, $388 thousand), the Bureau of Near Eastern Affairs (13 awards, $185 thousand), and the Bureau of European and Eurasian Affairs (10 awards, $284 thousand). A single GSA Federal Acquisition Service award for $500 thousand is an outlier in an otherwise State Department-locked portfolio.

Multistack holds multiple indefinite delivery contracts anchoring task-order work across State Department regional bureaus. Named IDVs include a $250,000 multiple-award contract with the Bureau of African Affairs for chiller service and maintenance (February 2023, through January 2028); a $129,271 contract with the Bureau of European and Eurasian Affairs for preventive maintenance, repairs, and spare parts at Kosovo and other European facilities (April 2025, through March 2030); a $105,000 multiple-award contract with the Bureau of Overseas Building Operations for DHRC (Diplomatic Residence HVAC and Refrigeration Component) system support (September 2024, through September 2027); and a $61,086 multiple-award contract with the Bureau of East Asian and Pacific Affairs for preventive maintenance on multistack modular water-cooled chillers across the region (August 2026, through July 2029). The source identifies these as multiple-award vehicles; task orders issued under them range from $15 thousand to $48 thousand in recent examples. The top parent vehicles by task-order volume are indefinite delivery contracts valued between $61 thousand and $178 thousand ceiling, each carrying four to five delivery orders.

Activity has remained consistent over recent years—33 awards in 2022, 27 in 2023, 33 in 2024, 26 in 2025, and 23 in 2026 (partial year)—with no pronounced growth or decline trajectory. The combined potential value across all awards is $26.7 million, with $25.8 million already obligated (97% utilization). A modest recompete exposure looms: 19 awards with ultimate completion dates in the next twenty-four months carry combined potential value of $1.7 million, representing less than 7 percent of the portfolio and signaling limited near-term contract churn risk.

Multistack's subcontracting footprint is minimal. The source names four prime contractors under which Multistack supplies components: BL Harbert International LLC (for modular scroll air-cooled water chillers supporting a new embassy compound in Malawi and a facility in the Republic of Congo), Chugach Intelligence Solutions LLC (for chiller and HVAC repairs at a recreational facility in Belmopan, Belize), and Alutiiq Information Management LLC (for an option-year funding modification). These sub-awards total less than 1 percent of the portfolio and reflect Multistack's position as a specialized HVAC equipment and components supplier to larger construction and facilities-management primes rather than as a dependent subcontractor.

The source's award descriptions characterize Multistack as a critical supplier to the State Department with a specialized role in supporting diplomatic facilities worldwide. The company's capability concentration in modular chillers, water-cooled and air-cooled variants, compressors, heat exchangers, and preventive maintenance aligns tightly with Department of State facility requirements across Africa, Europe, Asia, the Middle East, and Latin America. The company manufactures goods and performs services directly, with administrative and manufacturing operations based in Sparta, Wisconsin, and performance spanning overseas locations and the company's domestic facility depending on contract scope. With no SBA certifications, no participation in set-asides, and an awards footprint locked to a single department (State) and effectively a single bureau within it (Overseas Building Operations), Multistack operates as a niche supplier dependent on the continuity and scope of State Department HVAC infrastructure investment at diplomatic posts globally.