Multistack LLC

Multistack LLC, a Wisconsin-based for-profit HVAC equipment manufacturer and service provider, operates as a prime contractor delivering modular chillers, compressors, heat exchangers, pumps, controllers, sensors, and related cooling-system components and maintenance services to the Department of State's overseas diplomatic facilities, competing exclusively in full-and-open federal markets with no set-aside designations across 579 total awards.

Multistack is structured as a partnership or limited liability partnership headquartered in Sparta, Wisconsin, with a named subsidiary, Multistack BAC LLC. The company manufactures air-conditioning and refrigeration equipment (primary NAICS 333415) and serves as a direct prime contractor on 575 awards (99% of activity) with minimal subcontracting exposure. Federal work centers almost entirely on HVAC equipment supply, spare parts, preventive maintenance, repairs, and system upgrades at U.S. embassies and consulates worldwide. Representative prime work includes a $231,926.89 definitive contract with the Bureau of Overseas Building Operations for multistack chiller and air handling unit service and preventive maintenance in India through January 2031; a $295,768 definitive contract for preventive maintenance on chillers and air handling units at the U.S. Embassy in Pakistan through August 2027; and a $163,025.10 definitive contract for mission and PCC chillers annual maintenance in Switzerland through December 2027.

Customer concentration is extreme. The Bureau of Overseas Building Operations (OBO) accounts for 473 awards and $19.5 million in combined potential value, representing 92% of award count and 75% of total dollars. The next tier of State Department regional bureaus—East Asian and Pacific Affairs (19 awards, $411 thousand), the base State Department entity (15 awards, $654 thousand), Near Eastern Affairs (13 awards, $185 thousand), and European and Eurasian Affairs (10 awards, $284 thousand)—collectively add $1.5 million but remain minor relative to OBO dominance. GSA Federal Acquisition Service and the Bureau of African Affairs round out the customer set with single-digit and low-dollar activity. This concentration reflects Multistack's specialized role as OBO's dedicated HVAC supplier for diplomatic facilities, with work performed across Pakistan, Honduras, Australia, Saudi Arabia, India, Senegal, Zimbabwe, Kosovo, Malta, Norway, Mali, Oman, Lithuania, Ecuador, Peru, Brunei, and dozens of other overseas locations.

Multistack holds four active multiple-award indefinite delivery contracts anchoring its task-order work: a $250,000 IDC with the Bureau of African Affairs for chiller service and maintenance (ultimate completion January 2028); a $129,271 IDC with the Bureau of European and Eurasian Affairs for preventive maintenance and spare parts at diplomatic facilities in Kosovo and the region (April 2030); a $105,000 IDC with the Bureau of East Asian and Pacific Affairs for DHRC system support (September 2026); and a $95,938 IDC with the Bureau of European and Eurasian Affairs for annual chiller service at diplomatic facilities, primarily Kosovo (May 2025). These vehicles support the company's ability to issue delivery orders and purchase orders at speed in response to overseas facility maintenance emergencies and planned preventive maintenance cycles. Top parent vehicles by task-order volume include IDC 191D3219D0010 (5 task orders, $133 thousand), IDC 19CB6021D0001 (5 task orders, $79 thousand), and IDC 19KV4221D0006 (4 task orders, $72 thousand), all carrying discrete equipment and maintenance deliveries.

Activity has remained stable year over year—33 awards in 2022, 27 in 2023, 33 in 2024, 26 in 2025, and 12 year-to-date in 2026—with 16 awards (combined potential value $1.5 million) reaching ultimate completion within the next twenty-four months and therefore facing recompete. Multistack's subcontracting footprint is minimal (4 awards, 1% of total). Named sub work includes chillers and HVAC repairs under Chugach Intelligence Solutions for the Belmopan, Belize embassy compound; modular scroll air-cooled chillers under BL Harbert International for construction and new-embassy work in Lilongwe, Malawi and under economic price adjustment for material and equipment procurement; and logistics support under Alutiiq Information Management.

The vendor's entire portfolio clusters around HVAC equipment manufacturing and maintenance. Top NAICS codes are Air-Conditioning and Warm Air Heating Equipment Manufacturing (218 awards), Plumbing, Heating, and Air-Conditioning Contractors (34 awards), and Refrigeration Equipment Merchant Wholesalers (25 awards). Top PSC codes reflect the same footprint: Air Conditioning Equipment (125 awards), Refrigeration and Air Conditioning Components (85 awards), and Compressors and Vacuum Pumps (28 awards). Multistack has been registered in SAM.gov since April 2003, establishing more than two decades of federal contracting history focused on State Department facility support. The company competes exclusively on price and technical capability in unrestricted, full-and-open federal procurements; no awards carry SBA set-aside designations.