U.S. Boiler Company ES2 ES24
The U.S. Boiler Company ES2 ES24 is the second size, stepping up to a 5-inch vent: 105 MBH input with 89 MBH DOE heating capacity and a 77 MBH net AHRI water rating at 85.0% AFUE, chimney vented in 5" on the IQ Control System.
Key figures
- Max input
- 105 MBH
- Max CSA output
- —
- AFUE
- 85 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
U.S. Boiler Company ES2 ES24 in practice
The ES2 ES24 is a cast-iron, chimney-vented gas water boiler rated at 105 MBH input. Its row in the ES2 Product Data Sheet (Form HYDL09081) prints 89 MBH DOE heating capacity, a 77 MBH net AHRI water rating at a 1.15 piping and pickup allowance, and 85.0% AFUE, with a 5" vent and 3 gallons of boiler water.
The boiler ships at approximately 301 lb and measures 15-1/2" wide by 41 inches high by 33 inches deep, connecting on 1-1/4" supply and return with a 1/2" gas valve. Standard equipment includes the Intelligent Hydronic Control with a three-digit status/error readout, the IQ Option Panel for plug-and-play outdoor reset with DHW priority, low water cutoff and auxiliary high limit, a step-opening redundant gas valve, stainless-steel flue baffles, spark ignition with retry, a circulator and a resettable blocked vent switch. Ratings are certified to 2,000 feet and decrease three percent per 1,000 feet above that, with altitude kits required above 5,400 feet.
Boilers.ca documents this size at model level from the ES2 Product Data Sheet and links the published I&O manual. Gas, venting and electrical work belongs with a licensed contractor. No official Canadian-sales statement was found, so canadianStatus stays 'unknown'.
Best suited to
- 105 MBH residential heat-loss loads
- Replacement installations in homes with an existing chimney
- Owners wanting the IQ Option Panel's plug-and-play outdoor reset
Applicability and support
- Model number
- ES24
- 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 U.S. Boiler Company. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Input | 105 MBH | Input rating per the ES2 Product Data Sheet ratings table (sea level to 2,000 ft; ratings decrease three percent per 1,000 ft above that). |
| Output | ||
| DOE heating capacity | 89 MBH | DOE heating capacity per the ES2 Product Data Sheet ratings table. |
| Net AHRI water rating | 77 MBH | Net AHRI water rating per the ES2 Product Data Sheet, based on a piping and pickup allowance of 1.15. |
| Efficiency | ||
| Efficiency (AFUE) | 85 % | 85.0% AFUE per the ES2 Product Data Sheet ratings table; the product page carries an 85% AFUE headline. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater | |
| Venting and air | ||
| Vent size | 5" | Vent size per the ES2 Product Data Sheet ratings table; the boiler is chimney vented with an integrated draft diverter, damper and connector included. |
| Venting | Chimney vented (natural draft) with integrated draft diverter | The ES2 is designed for homes with existing chimneys; altitude conversion kits are required above 5,400 feet (kits do not convert gas type). |
| Physical and connections | ||
| Approx. shipping weight | 301 lb | Approximate shipping weight per the ES2 Product Data Sheet ratings table. |
| Dimensions (width × height × depth) | 15-1/2" × 41" × 33" | ES2 dimension table values; height and depth are common across the line. |
| Boiler water content | 3 gal | Water content per the ES2 Product Data Sheet dimensions and connections table. |
| Supply/return connections | 1-1/4" supply and 1-1/4" return | Water connection sizes per the ES2 Product Data Sheet connections table. |
| Gas valve connection | 1/2" | Gas valve connection per the ES2 Product Data Sheet connections table. |
| Operating limits and other | ||
| Control | Intelligent Hydronic Control with three-digit readout and IQ Option Panel | Combines aquastat, relay and ignition functions; the IQ Option Panel accepts plug-and-play IQ Option Cards for outdoor reset with DHW priority, low water cutoff and auxiliary high limit. |
| Fuel | Natural gas or LP gas | Available for natural or LP gas per the ES2 Product Data Sheet ratings note. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What are the ES2 ES24's ratings?
105 MBH input, 89 MBH DOE heating capacity, a 77 MBH net AHRI water rating and 85.0% AFUE with a 5" vent per the ES2 Product Data Sheet.
Does the ES2 ES24 need a chimney?
Yes — the ES2 is a chimney-vented natural-draft boiler with an integrated draft diverter; this size lists a 5" vent. Homes without a chimney are the use case for the power-vented PVG line.
Questions about the U.S. Boiler Company ES2 ES24?
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.
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- Buying guide
Sources and verification
- U.S. Boiler Company — ES2 Gas-Fired Water Boiler product page · accessed September 9, 2026
- ES2 Product Data Sheet, Form HYDL09081 (PDF) · HYDL09081 · accessed September 9, 2026
- ES2 Installation, Operating and Service Instructions (PDF) · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.