U.S. Boiler ES2
Model Number: ES2
ES2 is a U.S. Boiler cast-iron gas hot-water boiler for chimney venting.
Technical Specifications
Source: manufacturer spec sheet · checked Sep 27, 2026
Prices depend on sizing, venting and piping in your home, so we quote every installation.
Sizing: the right size comes from a room-by-room heat-loss calculation, not the size of the old boiler or a rule of thumb. Oversized boilers short-cycle and waste fuel; steam systems are sized to the connected radiation instead. See how we approach boiler installation.
Home-Specific Operating Cost Review
No guaranteed annual savings or payback period
Historical Use
Fuel consumption and weather
Current Rates
Utility and delivered-fuel prices
System Design
Load, piping, controls, and temperatures
Full Specifications
- Model Number
- ES2
- Efficiency (AFUE)
- 85%
- Boiler Type
- Hot Water Boiler
- Fuel
- natural gas
- Venting
- chimney
- BTU Input Range
- 70k - 280k BTU
- Domestic Hot Water
- indirect-ready
- In Production
- Yes
- Heat Exchanger Warranty
- Lifetime limited
Specifications sourced from the manufacturer spec sheet, checked Sep 27, 2026.
Ideal For
Gas hot-water homes keeping chimney venting
Expert Review: U.S. Boiler ES2
ES2 is a U.S. Boiler cast-iron gas hot-water boiler for chimney venting, listed at 70–280 MBH input and 85% AFUE.
The data sheet shows a lifetime limited heat exchanger warranty and domestic hot water through an optional indirect tank. The parts warranty term was not stated in the portion reviewed, so request the current certificate.
Because it is non-condensing and chimney vented, the chimney must be inspected and lined as required. Size from a room-by-room heat-loss calculation.
Key Features & Technology
The ES2 data sheet lists 70–280 MBH input for natural gas.
Cast-iron heat exchanger with chimney venting.
Rated at 85% AFUE.
Lifetime limited heat exchanger warranty.
Domestic hot water via an optional indirect tank.
Advantages
- High non-condensing efficiency for a chimney-vented cast-iron boiler.
- Wide 70–280 MBH range.
- Can pair with an indirect water heater.
Considerations
- Needs a suitable, lined chimney.
- Non-condensing, so fuel use is higher than a condensing boiler.
- Parts warranty term was not confirmed in the data sheet; request the certificate.
Sizing & Installation Notes
Hot water boilers like the ES2 are sized from a room-by-room heat-loss calculation. We never match the old boiler's size — oversized units short-cycle, waste fuel and wear out years early.
Every U.S. Boiler Company installation starts with a free in-home assessment covering the heat-loss calculation, venting and chimney condition, and gas or oil supply sizing. Learn more about our boiler installation process, or see current rebate and incentive programs that may apply.
Warranty & Protection
Parts Warranty
See spec sheet
Heat Exchanger
Lifetime limited
Our Guarantee
100% Satisfaction
All U.S. Boiler Company boiler installations by Home+ Air & Heat include our 1-year workmanship warranty, covering labor and any installation-related issues.
Compare the U.S. Boiler Company Lineup
| Model | Efficiency | BTU Range | Fuel | Heat Exchanger Warranty |
|---|---|---|---|---|
| ES2 (this model) | 85% AFUE | 70k - 280k BTU | natural gas | Lifetime limited |
| Alta | 95% AFUE | 14k - 200k BTU | natural gas/propane | lifetime limited |
| K2 | 95% AFUE | 80k - 180k BTU | natural gas/propane | lifetime limited |
| Ambient electric | Not verified | Various sizes available | electric | — |
| Aspen | 96% AFUE | 9k - 399k BTU | natural gas/propane | lifetime limited |
| Ambient HP | Not verified | Various sizes available | electric | — |
See the full U.S. Boiler Company brand page for lineup context, or browse the Best Hot Water Boilers 2027 guide to compare across brands.
Frequently Asked Questions
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