The short answer
There is no single best industrial boiler manufacturer; the right maker depends on the boiler type, size and pressure you need and on who can service it near you. For packaged firetube steam in North America, Cleaver-Brooks, Superior, Hurst and Fulton cover most sizes; for modular low-water-volume steam, Miura; for large field-erected or high-pressure watertube, Babcock & Wilcox, Rentech, Cleaver-Brooks and Superior; in Europe, Bosch and Viessmann (Vitomax) shell boilers. Ownership changed in 2024–2025: Miura bought Cleaver-Brooks and Watts bought Superior Boiler.
- Miura Co., Ltd. acquired Cleaver-Brooks in May 2024 for $774 million in cash, so the largest US packaged-boiler maker and the largest Japanese one now share an owner.
- Superior Boiler (Hutchinson, Kansas) joined Watts Water Technologies in November 2025; the product lines and brand continue.
- Viessmann Climate Solutions became part of Carrier on January 2, 2024; Viessmann’s Vitomax industrial boiler pages now carry Carrier branding.
- Babcock & Wilcox sold its Vølund (April 2025), Diamond Power (July 2025) and ASH (October 2025) businesses but still offers industrial package watertube boilers from 10,000 to 1,200,000 lb/h.
- Published firetube sizes top out around 2,500 boiler horsepower (Cleaver-Brooks CBEX, Superior Wichita/Apache/Dakota); above that, makers move to watertube designs.
| Maker | Owner (2026) | Main types | Flagship lines | Size range (as published) | Notes |
|---|---|---|---|---|---|
| Cleaver-Brooks | Miura Co., Ltd. (since May 2024) | Firetube, packaged and industrial watertube, electric, electrode | CBEX firetube; CBCW, A/D/O-type watertube; FLX, M5; CR/HSB/MVE electric | CBEX 100–2,500 HP; CBCW 10,000–225,000 lb/hr; MVE electrode 1–102 MW | Integrated boiler, burner and Hawk controls from one maker |
| Miura | Miura Co., Ltd. (Japan) | Modular once-through watertube | LX gas-fired, EX dual-fuel | LX 50–300 BHP per module | Built in Rockmart, Georgia; claims steam in under 5 minutes from cold |
| Fulton | Fulton (Palm family, Pulaski, NY) | Vertical tubeless, firetube, flexible watertube, electric | Classic, VMP, VSRT, FBS, FBX, FBE/FBL/FBZ | Classic 4–60 BHP; FBS 60–1,000 BHP; FBX 31–920 BHP; electric to 3,000 kW | Hybrid gas/electric VSRT-E 9.5–60 BHP |
| Bryan Steam | Burnham Holdings | Flexible watertube, electric | RV, RW, AB, BH electric | RW 200–527 BHP output; BH electric 60–3,000 kW | Mainly hot water and lower-capacity steam |
| Hurst Boiler | Hurst Boiler & Welding Co. (Coolidge, GA) | Scotch marine firetube, firebox, vertical, watertube, biomass | Scotch Marine, Performance Series watertube, solid-fuel systems | Firetube 15–800 hp to 300 psig; watertube 17,250–103,500 lb/hr | One of few US makers with a full solid-fuel line |
| Superior Boiler | Watts Water Technologies (since Nov 2025) | Scotch marine firetube, D/O/A-type watertube, HRSG, vertical | Wichita, Apache, Dakota, Seminole; Ottawa, Shawnee, Tomahawk | Firetube to 2,500 HP; watertube 10,000–500,000 lb/hr | Customized designs are a stated focus |
| Viessmann (Vitomax) | Carrier (Viessmann Climate Solutions since Jan 2024) | Shell (firetube) steam and hot water, electric and hybrid | Vitomax HS, HW, LW; HS-E, HS-EH | Steam 0.5–31.5 t/h; hot water 0.65–22 MW | Hydrogen-capable with a suitable burner, per Viessmann |
| Bosch Industrial | Bosch (Bosch Industriekessel GmbH) | Shell (firetube) steam and hot water, electric | UL-S, ZFR, CSB, ELSB | Steam 175–55,000 kg/h; ELSB 350–8,300 kg/h at up to 24 bar | New ELHB electric hot water boiler shown February 2025 |
| Rentech | Rentech Boiler Systems, Inc. (Abilene, TX) | Fired packaged watertube, HRSG, waste heat | D-, A- and O-type packaged watertube | 20,000–600,000 lb/hr; 200–2,000 psig; to 1,000°F | Engineered to order |
| Babcock & Wilcox | Babcock & Wilcox Enterprises (NYSE: BW) | Package and field-erected watertube, utility, fluidized bed | FM, HCFM, PFM, PFI, TSSG | 10,000–1,200,000 lb/h; 250–2,400 psig | Sold Vølund, Diamond Power and ASH units in 2025 |
The shortlist
1Cleaver-Brooks
Best for: Plants that want one supplier for firetube, watertube or electric steam with matched burner and controls.
Cleaver-Brooks has the broadest packaged range of any maker here. The CBEX firetube runs 100 to 2,500 HP, steam to 300 psig and hot water to 125 psig, in 2-pass wetback (CBEX-2W), 2-pass dryback (CBEX-2D) and 3-pass wetback (CBEX-3W, 250–800 HP) forms. Industrial watertube covers A-, D- and O-type designs and the configured CBCW line (10,000 to 225,000 lb/hr, 100 to 550 psig). Electric steam runs from the 12 kW Model CR to the Model MVE electrode boiler at 1 to 102 MW. Miura completed its purchase of the company in May 2024.
- Single source for boiler, burner and Hawk controls, which simplifies commissioning and parts.
- CBEX lists sub-5 ppm NOx without SCR on most models and 30 ppm across a 10:1 turndown.
- Large rental fleet and an established North American rep and parts network.
- Integration under Miura is still recent; confirm the local rep and parts arrangements for your region.
- Hawk controls are proprietary; check who in your area is trained to service them.
Maker’s page: Cleaver-Brooks (Miura group)
2Miura
Best for: Steam loads that swing or run intermittently, and boiler rooms short of floor space.
Miura builds modular once-through watertube steam boilers with a small water volume, installed in multiples and sequenced to the load. The LX gas-fired series runs 50 to 300 BHP per unit (1,730 to 10,350 lb/hr), in 15 psi low-pressure, 70–150 psi standard and 170–270 psi high-pressure versions; the EX series adds #2 oil firing for sites that need a backup fuel. Miura says its boilers reach full steam in under 5 minutes from a cold start and that more than 140,000 of its once-through units are in operation.
- Fast start means boilers can be cycled off instead of held hot on standby.
- NOx as low as 5 ppm at 3% O2 on LX models, per Miura.
- No tube-pull or door-swing clearance needed, so modules fit tight rooms.
- Low-water-volume designs depend on good feedwater treatment; budget for the water treatment Miura specifies.
- Large loads need many modules, which means more burners and controls to maintain.
Maker’s page: Miura America
3Fulton
Best for: Small to mid-size steam users who want vertical tubeless, firetube, watertube and electric options from one maker.
Fulton, still run by the founding Palm family in Pulaski, New York, makes the vertical tubeless Classic (4–60 BHP), VMP (40–150 BHP) and VSRT (9.5–250 BHP) steam boilers, the FBS horizontal firetube (60–1,000 BHP, design pressure to 300 psi, 82% efficiency per Fulton) and the FBX flexible watertube (31–920 BHP). Its electric line covers FBE (12–180 kW), FBL (12–1,000 kW) and FBZ (90–3,000 kW), and the VSRT-E is a hybrid gas and electric boiler.
- Tubeless vertical designs avoid retubing.
- Electric and hybrid options for sites planning to electrify in stages.
- FBS and FBX are listed as biofuel-ready and 20% hydrogen-ready.
- Largest firetube is 1,000 BHP; bigger single-boiler loads need another maker.
- Confirm efficiency figures on the same basis (HHV, fuel-to-steam) when comparing quotes.
Maker’s page: Fulton Heat Transfer
4Bryan Steam (Bryan Boilers)
Best for: Hot water and low-to-medium steam loads where a flexible watertube boiler suits the space.
Bryan, a Burnham Holdings commercial subsidiary, builds forced-draft flexible watertube boilers for hot water and steam. The RV series covers 84 to 201 BHP output and the RW series 200 to 527 BHP output, gas, oil or dual fuel. Its BE and BH electric boilers cover 30 to 3,000 kW input in hot water and steam versions.
- George Bryan invented the flexible watertube design, and Bryan has built it for decades.
- Hot water, steam and electric from one rep.
- Range stops around 527 BHP; it is not a high-capacity industrial steam supplier.
- Several older series (CLM, HE-AB, HE-RV) are listed as discontinued; confirm parts support if you run one.
Maker’s page: Bryan Steam LLC (Burnham Holdings)
5Hurst Boiler
Best for: Plants burning biomass or solid fuel, or wanting firetube and watertube from a US fabricator.
Hurst has built boilers in Coolidge, Georgia since 1967. Its Scotch marine firetube boilers come in 2-, 3- and 4-pass, dryback or wetback, steam or hot water, from 15 to 800 hp at pressures to 300 psig, rated at 81% minimum efficiency. The Performance Series watertube spans 17,250 to 103,500 lb/hr (500 to 3,000 hp). Hurst also builds firebox, vertical, hybrid and solid-fuel (wood, biomass, coal) systems.
- Full biomass and solid-fuel range alongside gas- and oil-fired boilers.
- Skid-packaged systems and its own Firemaster controls and Stackmaster economizer.
- Firetube line stops at 800 hp; larger firetube loads mean multiple boilers or another maker.
- Check service coverage outside the Southeast before you commit.
Maker’s page: Hurst Boiler & Welding Co., Inc.
6Superior Boiler
Best for: Custom or unusual firetube and watertube specifications, including large dryback and waste heat units.
Superior, based in Hutchinson, Kansas since 1917, became part of Watts Water Technologies in November 2025. It builds Scotch marine firetube boilers up to 2,500 HP (Wichita wetback 100–2,500 HP; Apache dryback 10–2,500 HP; Dakota 100–2,500 HP), D-, O- and A-type watertube from 10,000 to 300,000 lb/hr and the Tomahawk at 250,000 to 500,000 lb/hr, plus HRSGs, waste heat, vertical and condensing boilers.
- Wide firetube size range with both wetback and dryback options.
- States that it built the largest single-furnace firetube boiler in the industry, a 2,200 hp dryback.
- New ownership: confirm warranty, lead time and rep coverage under Watts.
- Custom designs mean longer engineering time than a catalog unit.
Maker’s page: Superior Boiler (Watts Water Technologies)
7Viessmann Vitomax
Best for: European and export projects that want shell steam or hot water boilers with electric or hybrid options.
Vitomax is Viessmann’s industrial shell-boiler family. Vitomax HS high-pressure steam boilers cover 0.5 to 31.5 t/h; Vitomax hot water boilers run from 0.65 to 22 MW. HS-E boilers use electric heating elements only and HS-EH combines a burner with two electric heating elements. Viessmann says Vitomax boilers can fire up to 100% hydrogen with a suitable burner. Carrier completed its purchase of Viessmann Climate Solutions on January 2, 2024, and the Vitomax pages now carry Carrier branding.
- Electric and hybrid versions within the same family.
- Over 95.5% efficiency stated for low-pressure hot water boilers with a flue gas heat exchanger.
- North American industrial presence is smaller than the US makers; check ASME stamping and local service.
- Quoted efficiencies are often on a European (LHV) basis; convert before comparing with US HHV figures.
Maker’s page: Viessmann (Carrier)
8Bosch Industrial
Best for: Shell-boiler steam up to 55 t/h, and sites adding electric steam beside gas.
Bosch’s industrial boilers cover 175 to 55,000 kg/h of steam. The UL-S three-pass boiler runs 1,250 to 28,000 kg/h at up to 30 bar, the ZFR double-flame-tube boiler 18,000 to 55,000 kg/h, and the CSB 300 to 23,600 kg/h. The ELSB electric steam boiler now lists 350 to 8,300 kg/h at up to 24 bar. In February 2025 Bosch showed the ELHB electric boiler for hot water (250 to 5,500 kW at up to 16 bar).
- UL-S integrated economizer and optional condensing heat exchanger.
- Electric (ELSB) and gas (UL-S) units are designed to run side by side, as at PepsiCo Poland, per Bosch.
- Specs are published in kg/h and bar; convert carefully (1,000 kg/h is about 2,205 lb/h).
- Check North American code stamping and service coverage for US projects.
Maker’s page: Bosch Industriekessel GmbH
9Rentech
Best for: Engineered high-pressure or superheated watertube boilers, HRSGs and waste heat boilers.
Rentech, founded in 1996 in Abilene, Texas, designs fired packaged watertube boilers in D-, A- and O-type arrangements from 20,000 to 600,000 lb/hr, 200 to 2,000 psig and saturated to 1,000°F steam. It recommends D-type for 20,000 to 600,000+ lb/hr, A-type for 150,000 to 250,000 lb/hr and O-type where footprint is limited up to 100,000 lb/hr. It also builds HRSGs, waste heat boilers and economizers.
- Engineered to the application, including refinery gas, hydrogen and high flue-gas pressure.
- Repair services for other makers’ watertube boilers.
- Not a catalog packaged-boiler supplier; expect engineering lead time.
- Minimum size (20,000 lb/hr) is above most small plant needs.
Maker’s page: Rentech Boiler Systems, Inc.
10Babcock & Wilcox
Best for: Large industrial and utility steam at high pressure and capacity.
B&W’s industrial package boilers (FM, HCFM, PFM, PFI, PFT and TSSG models) cover 10,000 to 1,200,000 lb/h and 250 to 2,400 psig, shop-assembled or modular. It also builds utility boilers and bubbling and circulating fluidized-bed boilers. In 2025 it sold Vølund (April 29), Diamond Power (July 31) and its ASH business (October 31), according to its annual report.
- Highest pressure and capacity range on this list.
- Burner pairing with John Zink Hamworthy Combustion (Coen burners) for complete packages.
- Portfolio is still being reshaped; confirm which entity supports aftermarket parts you rely on.
- Overkill for plants under about 10,000 lb/h.
Maker’s page: Babcock & Wilcox Enterprises
What changed in 2024–2026
Three ownership changes affect who you buy from and who backs the warranty. None of them has removed a product line so far, but each is worth a question to your rep about parts, lead times and service contracts.
| Date | Change | What it means on site |
|---|---|---|
| 2 Jan 2024 | Carrier completed its acquisition of Viessmann Climate Solutions from the Viessmann Group. | Vitomax industrial boilers are sold on Viessmann sites that identify Viessmann as part of Carrier. |
| May 2024 | Miura Co., Ltd. acquired Cleaver-Brooks from Harbour Group for $774 million in cash. | Cleaver-Brooks firetube, watertube and electric lines and Miura modular watertube now sit in one group. |
| 2 Jul 2024 | Carrier sold its industrial fire business, including Fireye burner controls, to Sentinel Capital Partners, forming Spectrum Safety Solutions. | Fireye flame safeguards used on many packaged boilers now have a new parent. |
| Apr–Oct 2025 | Babcock & Wilcox sold Vølund (29 Apr), Diamond Power (31 Jul) and ASH (31 Oct). | Sootblower and ash-handling support that came from those units now comes from their new owners. |
| Nov 2025 | Watts Water Technologies completed its acquisition of Superior Boiler. | Superior keeps its Hutchinson, Kansas plant and brand; Watts adds custom steam and hot water boilers. |
How to shortlist a boiler maker
- Fix the duty first: steam or hot water, operating pressure, peak and minimum load in lb/hr or BHP, and whether you need superheat. That alone rules most makers in or out.
- Match the type: firetube for saturated steam up to about 300 psig and roughly 2,500 HP per boiler; modular watertube where loads swing; industrial watertube for high pressure, superheat or very large capacity; electric where emissions or fuel access drive the choice.
- Ask for efficiency on the same basis from every bidder: fuel-to-steam, HHV, at your firing rates, with and without economizer.
- Check emissions guarantees against your air permit (NOx and CO in ppm at 3% O2) at low fire as well as high fire.
- Confirm the burner management and combustion controls supplied, who services them locally, and how fault history is retrieved.
- Ask who stocks parts within a day’s drive and what the response time for a lockout call is.
Sizing units you will see in quotes
US makers quote in boiler horsepower (BHP) or lb/hr; European makers in kg/h, t/h or MW. One boiler horsepower is 33,475 Btu/hr, which evaporates about 34.5 lb/hr of water from and at 212°F (100°C). Miura’s LX 50, for example, is 50 BHP and 1,730 lb/hr. One t/h is about 2,205 lb/hr, so Bosch’s 55,000 kg/h ZFR is roughly 121,000 lb/hr, and Viessmann’s 31.5 t/h Vitomax HS is about 69,400 lb/hr.
- Firetube ratings are usually “from and at 212°F”; actual output at 125 psig with 227°F feedwater is a few percent lower.
- Watertube ratings in lb/hr normally state pressure and temperature; check both before comparing.
- Electric boiler ratings are in kW; 1 BHP is about 9.8 kW.
How we compared them
We included makers with a large installed base in North America or Europe, a current product page with published sizes, a range that covers industrial steam (not only residential or light-commercial hot water), and a dealer or service network. We read each maker’s own product pages on 26 October 2026 and report sizes exactly as published; where a maker gives no figure we leave it out. Ownership facts come from the buyer’s or seller’s own statements, the maker’s site or SEC filings. The list is unranked and in no order of quality. Thermax was considered but left out because its site blocked our access and we could not confirm current specifications. InduQT sells and services none of this equipment.
Frequently asked questions
Who is the largest industrial boiler manufacturer?
Miura describes itself as the largest industrial boiler manufacturer in the world, and since May 2024 it also owns Cleaver-Brooks, the best-known US packaged boiler brand. By capacity, utility and field-erected watertube suppliers such as Babcock & Wilcox build the largest single units.
Is Cleaver-Brooks still an American company?
Cleaver-Brooks still designs and builds boilers in the US and is headquartered in Thomasville, Georgia, but its owner since May 2024 is Miura Co., Ltd. of Japan, which paid $774 million in cash.
Who owns Superior Boiler now?
Watts Water Technologies completed its acquisition of Superior Boiler in November 2025. Superior continues to operate from Hutchinson, Kansas under its own brand.
Should I choose a firetube or a watertube boiler?
Choose firetube for saturated steam below about 150–300 psig and up to roughly 2,500 HP per boiler when loads are steady. Choose watertube for higher pressure, superheated steam, very large capacity or loads that swing, where low water volume and fast start help.
Which boiler makers offer electric steam boilers?
Among the makers here, Cleaver-Brooks (Model CR, S, HSB, MVR and MVE electrode), Fulton (FBE, FBL, FBZ), Bryan (BE, BH), Bosch (ELSB) and Viessmann (Vitomax HS-E) all publish electric steam boilers.
What efficiency should I expect from a new industrial boiler?
Makers publish fuel-to-steam figures in the low to mid 80s percent for gas-fired steam without condensing: Hurst states 81% minimum for Scotch marine, Fulton 82% for FBS and Miura about 85%. Economizers add a few points; each 40°F drop in stack temperature is worth about 1%, according to the US DOE.
Is Bosch selling its industrial boiler business?
We found no confirmed sale. Bosch Industriekessel continues to market its UL-S, ZFR, CSB and ELSB boilers and introduced the ELHB electric hot water boiler in February 2025.