What Williamson-Thermoflo does

Williamson-Thermoflo is a privately held HVAC equipment manufacturer operating under two established sub-brands, Williamson and Thermoflo, and headquartered at N93 W14635 Whittaker Way in Menomonee Falls, Wisconsin. The company designs and markets a residential and light commercial heating portfolio that includes gas-fired atmospheric and induced-draft water boilers (AFUE up to 84%), gas-fired condensing water and wall-mount boilers (AFUE 91% and 95% respectively), oil-fired water and steam boilers (AFUE 85-87%), a range of oil furnaces in low-boy, high-boy, and multi-position configurations (AFUE up to 87.5%), and glass-lined indirect-fired water heaters with capacities from roughly 30 to 110 gallons. Products incorporate modulating combustion, cast-iron and stainless-steel heat exchangers, variable-speed ECM blowers, and digital Honeywell controls, and the line is AHRI-certified with ENERGY STAR Program 3.0 compliance available on select oil-fired boilers with an optional OVD kit; B100 biofuel certification is offered on oil-fired models.

The company's go-to-market is exclusively indirect: equipment is sold through authorized plumbing, heating, and HVAC distributors across North America, with installation and service performed by licensed plumbers, HVAC contractors, oil dealers, and installers. Pricing is not publicly disclosed and revenue is generated via hardware sales to this distributor channel, with a dedicated internal support staff handling distributor and product inquiries. End demand is split between residential and light commercial use cases, and marketing is conducted primarily through a distributor locator, an extensive resource library of brochures and manuals, and AHRI directory listings. The firm reports only 1-10 employees, and its website links to SPX Corporation for privacy and terms, indicating a likely corporate or operational relationship with SPX, though no formal parent-subsidiary disclosure appears in the source data.

Name

Williamson-Thermoflo

Legal name

Williamson-Thermoflo

Website

https://www.williamson-thermoflo.com

Company type

Private

Founded year

1999

Operating status

Operating

Headcount range

1–10 employees

Short description

Williamson-Thermoflo is a privately held HVAC equipment manufacturer in Menomonee Falls, Wisconsin, selling gas-fired and oil-fired boilers, furnaces, and glass-lined water heaters under the Williamson and Thermoflo brands through authorized distributors to residential and light commercial customers across North America.

Ownership category

akta.pro rank

Product category

HVAC Heating Equipment Manufacturing

NAICS

Heating Equipment (except Warm Air Furnaces) Manufacturing (333414), Power Boiler and Heat Exchanger Manufacturing (332410), Air-Conditioning and Warm Air Heating Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing (333415)

SIC

Heating Equipment, Except Electric & Warm Air Furnaces (3433), Air-Cond & Warm Air Heatg Equip & Comm & Indl Refrig Equip (3585)

akta.pro primary industry

Boilers, Furnaces & Process Heating Equipment (IMAHAKAD)

akta.pro secondary industries

Heat Exchangers, Coils & Hydronic HVAC Components (IMADANAF), Heat Transfer Equipment (Heat Exchangers, Boilers, Condensers) (IMAHAEAC)

Keywords

• HVAC equipment manufacturing
• Gas-fired boilers
• Oil-fired boilers
• Indirect water heaters
• Residential heating systems

Headquarters

HQ city

Milwaukee

HQ country

United States

HQ region

North America

Offices1 record

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Supply Chain, Operations, Personnel, Technology or R&D, Marketing or Sales, Infrastructure

Revenue model

1. HVAC Equipment Sales: Sale of heating and cooling equipment (boilers, furnaces, water heaters) to authorized distributors and through to licensed plumbers, HVAC contractors, oil dealers, and installers in the residential and light commercial market.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels4 records

Core offering

Williamson-Thermoflo manufactures and sells residential and light commercial heating equipment—including oil-fired and gas-fired boilers (water, steam, atmospheric, induced-draft, and condensing models), oil furnaces, and glass-lined indirect-fired water heaters—under two established brands, Williamson and Thermoflo. Products are distributed exclusively through authorized plumbing, heating, and HVAC distributors across North America, with installation and service performed by licensed plumbers, professional HVAC contractors, oil dealers, and installers.

Product overview

Williamson-Thermoflo is an HVAC equipment manufacturer producing two brand lines—Williamson and Thermoflo—offering a comprehensive portfolio of residential and light commercial heating products. The product lineup centers on oil and gas-fired boilers (including water boilers, steam boilers, and condensing models), oil furnaces (packaged low boy, high boy, and multi-position configurations), and indirect water heaters. Both brands share essentially identical product families spanning: oil-fired equipment (OWB/OWT water boilers at 86-87% AFUE, OSB steam boilers at 85%, and various oil furnaces with AFUE up to 87.5%); gas-fired equipment (GWA/GWI atmospheric and induced draft water boilers at 84% AFUE, GSA steam boilers at 82%, GWC condensing boilers above 91%, and FreeStyle wall-mount condensing boilers at 95%); and GL glass-lined indirect water heaters. Products are distributed through authorized plumbing, heating, and HVAC distributors across North America.

Differentiator

Problem solved

Functional benefit

Brands

• Williamson: Leading name among heating and air conditioning brands with reputation for long-lasting, reliable performance.
• Thermoflo

Products and services

• FreeStyle – Series 2 – Wall Mount Gas-Fired Condensing Boiler

Quantifiable outcome

• FreeStyle condensing boiler achieves up to 95% AFUE energy efficiency with 10-to-1 turndown ratio
• +4 more outcomes

Segments3 records

Ideal customer profiles2 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature7 records

Scale indicators1 record

Recent moves4 records

Expansion highlights3 records

Direct peers

• Weil-McLain: U.S. manufacturer of residential and commercial cast-iron and condensing boilers. Directly comparable to Williamson-Thermoflo's OWB/OWT oil-fired and FreeStyle/GWC gas-fired condensing boiler lines, serving the same plumbing and HVAC distributor channel.
• U.S. Boiler Company: Manufacturer of residential and light-commercial gas- and oil-fired boilers including the Aspen, ES2, and K2 product families. Directly overlaps with Williamson-Thermoflo's oil-fired water/steam boiler and gas condensing portfolios and sells through the same HVAC distributor network.
• Burnham Holdings: Parent of Burnham, U.S. Boiler, and related hydronic brands producing cast-iron and condensing boilers plus oil-fired equipment. Closely comparable in product mix, channel, and target customer to Williamson-Thermoflo, including its oil-fired water and steam boiler lines.
• Slant/Fin: Manufacturer of residential and commercial boilers (baseboard and fin-tube) including high-efficiency gas and oil-fired models. Directly competes in the same hydronic heating category served by Williamson-Thermoflo, distributed through plumbing and HVAC wholesalers.
• Navien: Manufacturer of high-efficiency condensing gas boilers and combi-boilers (NFB, NFB-H, NCB) plus tankless water heaters. Directly comparable to Williamson-Thermoflo's FreeStyle condensing boiler and GL water heater lines in efficiency class and channel.
• Triangle Tube: Manufacturer of stainless-steel condensing gas boilers (Prestige Solo, Triumph) and indirect water heaters. Overlaps with Williamson-Thermoflo's GWC and FreeStyle condensing lines and GL indirect-fired water heater family.
• Peerless Boilers: Manufacturer of residential and commercial cast-iron oil-fired and gas-fired boilers including the Peerless WBV and WB-64 lines. Directly comparable in oil-fired water boiler product family and distributor-led channel approach.
• IBC Technologies: Manufacturer of high-efficiency stainless-steel modulating condensing boilers (VFC, SL, HC). Directly comparable to Williamson-Thermoflo's FreeStyle and GWC condensing products in efficiency class and hydronic channel.
• Dunkirk Boilers: Manufacturer of residential cast-iron gas and oil-fired boilers (DCC, DCB, XEB, WPSB) sold through plumbing/HVAC distributors. Directly comparable to Williamson-Thermoflo's atmospheric and oil-fired boiler product families.

Broad incumbents

• Bosch Thermotechnology: Global manufacturer of residential boilers, water heaters, and heat pumps sold through HVAC distributors. Overlaps with Williamson-Thermoflo's condensing boiler and water heater lines but operates at a much broader product and geographic scale.

Market position

Strengths4 records

Weaknesses4 records

Competitive moat3 records

Key risks6 records

Key highlights6 records

Customer concentration

Revenue estimate

Valuation estimate

Number of profiles

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Williamson-Thermoflo