Burnham · SteamMax & Independence (gas steam)
Burnham Independence IN3I
The Burnham Independence IN3I is a current gas-fired cast-iron steam boiler: 62 MBH maximum input for 51 MBH heating capacity and a 38 MBH net AHRI steam rating (158 sq ft) at 81.9% AFUE, requiring a 4 in. x 15 ft chimney and shipping at about 350 lb.
Key figures
- Max input
- 62 MBH
- Max CSA output
- —
- AFUE
- 81.9 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Burnham Independence IN3I in practice
The Independence IN3I is one of the 10 sizes U.S. Boiler Company documents for the Independence gas-fired cast-iron steam line. Its official submittal row prints 62 MBH maximum input, 51 MBH heating capacity and a 38 MBH net AHRI steam rating covering 158 sq ft (1.333 piping and pickup allowance), at 81.9% AFUE, with a 4 in. x 15 ft minimum chimney and a 350 lb approximate shipping weight.
The line is built with cast-iron push nipples, Honeywell operating controls, a vent damper and a rugged steel base under an insulated powder-coated steel jacket; the Independence PV variants are specifically configured as direct-vent products for homes with a damaged or irreparable chimney. The maximum working pressure is 15 PSI steam, and the product page prints a limited 10-year heat exchanger warranty plus a one-year manufacturer's parts warranty.
LP gas is available on the IN3–IN9 sizes per the submittal footnote and product page. No official Canadian-sales statement was found, so canadianStatus stays 'unknown', and gas, combustion and steam work belongs with a licensed contractor.
Best suited to
- Steam systems needing about 158 sq ft of connected radiation
- Residential steam replacements on a chimney-vented system
- Installations comparing chimney-vented and Independence PV direct-vent configurations
Applicability and support
- Model number
- IN3I
- Canadian availability
- unknown
- Production status
- current
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Burnham. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Maximum input | 62 MBH | Maximum input per the official Independence submittal/PDS ratings table (sea level to 2,000 ft; reduce 4% per 1,000 ft above sea level in the U.S.). |
| Output | ||
| Heating capacity | 51 MBH | Heating capacity per the official Independence submittal ratings table. |
| Net AHRI steam rating | 38 MBH | Net steam rating 38 MBH covering 158 sq ft, based on a piping and pickup allowance of 1.333 per the submittal. |
| Efficiency | ||
| Efficiency (AFUE) | 81.9 % | AFUE per the official Independence submittal ratings table (up to 82%). |
| Venting and air | ||
| Minimum chimney requirement | 4 in. x 15 ft | Round chimney diameter x height measured from the top of the draft hood to the top of the chimney, per the submittal (15 ft minimum). |
| Physical and connections | ||
| Approximate shipping weight | 350 lb | Approximate shipping weight per the official submittal. |
| Maximum working pressure | 15 PSI steam | As printed on the official Independence submittal. |
| Operating limits and other | ||
| Fuel | Natural gas or LP gas (on select chimney-vented models) | Per the submittal footnote and product page: LP is available on the IN3–IN9 sizes. |
| Construction | Cast-iron sections with push nipples, Honeywell operating controls, vent damper and insulated steel jacket | Per the official Independence product page; the PV variants are configured as direct-vent products for homes with a damaged or irreparable chimney. |
| Warranty | Limited 10-year heat exchanger warranty plus a one-year manufacturer's parts warranty | As printed on the official Independence product page. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What are the Independence IN3I's ratings?
62 MBH maximum input, 51 MBH heating capacity and a 38 MBH net AHRI steam rating (158 sq ft) at 81.9% AFUE per the official submittal.
What chimney does the IN3I need?
A 4 in. x 15 ft round chimney, measured from the top of the draft hood to the top of the chimney (15 ft minimum) per the official submittal.
Can the IN3I run on propane?
Yes — LP gas is available on the IN3–IN9 sizes per the submittal footnote and product page.
Questions about the Burnham Independence IN3I?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Compare and explore
- Burnham Independence IN3I vs Burnham SteamMax STMX075Comparison
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- Burnham Independence IN10-ISame series
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- Burnham SteamMax STMX200Same series
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- Burnham SteamMax STMX299Same series
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- Burnham SteamMax STMX500Same series
- Burnham SteamMax STMX550Same series
- SteamMax & Independence (gas steam) series hub
- Buying guide
Sources and verification
- U.S. Boiler Company — Independence / Independence PV Gas Fired Cast Iron Steam Boilers (IN3I) · accessed September 9, 2026
- Independence Product Data Sheet · accessed September 9, 2026
- Independence Series Submittal Form · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.