If your boiler is 20-plus years old, tripping the breaker, or pushing your winter gas bills higher every year, you are probably weighing replacement against another round of repairs. Weil-McLain is one of the names you will encounter in almost every US basement — but with nine residential product families spanning 80% cast iron to 95% condensing, the brand is easy to misjudge as a single product. This review breaks down the actual lineup, real installed costs in USD, AFUE and BTU specs, warranty terms, and the failure patterns technicians see in the field so you can decide with facts. If you are still mapping out the whole project, start with our boiler buying guide before you request quotes.
Who Is Weil-McLain?
Weil-McLain was founded in Chicago in 1881 and is headquartered in Michigan City, Indiana, where it still builds cast-iron sections and assembles condensing units. That domestic manufacturing history matters for two practical reasons: parts availability is excellent across the US, and nearly every licensed heating contractor has serviced a Weil-McLain at some point.
The company’s residential catalog splits into three buckets:
- Condensing gas/propane boilers (90–95% AFUE): Evergreen, ECO Tec, Ultra, AquaBalance, GV90+
- Non-condensing cast-iron gas boilers (80–85% AFUE): CGi, EG (steam), LGB (commercial)
- Oil-fired boilers (82–86% AFUE): WTGO (hot water), SGO (steam)
Because Weil-McLain covers steam and hot water, gas and oil, it is a common choice in older Northeast and Midwest homes where steam radiators and oil tanks are still in service — a niche many modern wall-hung brands ignore entirely.
Weil-McLain Boiler Lineup at a Glance
| Model | Type | AFUE | Input Range (BTU/h) | Typical Installed Cost |
|---|---|---|---|---|
| CGi | Cast-iron gas hot water | 82–84% | 67,000–225,000 | $3,500–$6,500 |
| GV90+ | Cast-iron gas hot water | 90% | 75,000–225,000 | $5,000–$8,000 |
| ECO Tec | Condensing wall-hung | Up to 95% | 70,000–199,000 | $4,500–$8,000 |
| Evergreen | Condensing wall-hung, modulating | Up to 95% | 70,000–220,000 | $5,000–$9,000 |
| AquaBalance | Condensing combi (heat + DHW) | Up to 95% | 80,000–155,000 | $6,000–$10,000 |
| Ultra | Condensing, commercial-grade | Up to 95% | 80,000–310,000 | $8,000–$18,000 |
| WTGO | Oil hot water | 85–86% | 105,000–280,000 | $4,500–$8,500 |
| SGO | Oil steam | 82–84% | 105,000–280,000 | $5,000–$9,000 |
Evergreen (Best Fit for Most Gas Retrofits)
The Evergreen is Weil-McLain’s flagship residential condensing boiler: a stainless steel fire-tube heat exchanger, a modulating burner with roughly 5:1 turndown, built-in outdoor reset, and a color touchscreen control that stores fault history. It is available in 70, 110, 155, and 220 MBH sizes, which lets a contractor match the unit closely to a Manual J heat-loss calculation rather than oversizing by 50% — the single biggest efficiency mistake in boiler replacement.
At 95% AFUE, an Evergreen is a legitimate upgrade from an 80% atmospheric cast-iron boiler. It also vents through PVC or CPVC (two-pipe direct vent), so it eliminates the metal chimney and the standby loss that comes with it.
ECO Tec (Value Condensing)
The ECO Tec is the more budget-conscious condensing wall-hung line, still reaching up to 95% AFUE with a stainless steel heat exchanger and a 70,000–199,000 BTU/h range. It is a strong pick when a homeowner wants condensing efficiency but the Evergreen’s touchscreen control and higher price point are not justified by the house.
Ultra (Heavy-Duty Condensing)
The Ultra is a condensing boiler built for larger homes and light commercial loads, with inputs up to 310,000 BTU/h and both wall-hung and floor-standing configurations. It is commonly found in apartment buildings, small schools, and large multifamily retrofits where a single high-mass boiler replaces two atmospheric units.
AquaBalance (Combi / Tankless DHW)
The AquaBalance combines space heating with on-demand domestic hot water, eliminating a separate 40–50 gallon indirect tank. Models run 80,000–155,000 BTU/h and deliver roughly 2.5–4.5 GPM of domestic hot water depending on the model and incoming water temperature. It is an excellent space saver for a closet or utility room — but verify the DHW flow rate against your actual fixture count before committing.
CGi, GV90+, and EG (Cast Iron and Steam)
The CGi remains one of the most reliable atmospheric cast-iron gas boilers sold in the US, with an 82–84% AFUE and a 20-plus-year service life typical in well-maintained systems. The GV90+ pairs a cast-iron primary block with a stainless secondary exchanger to hit 90% AFUE while keeping the thermal mass that some contractors prefer in cold climates. The EG is the steam version — if your home has one-pipe radiators and a sight glass, this is the category you need, not a condensing wall-hung unit.
WTGO and SGO (Oil-Fired)
For homes with an existing oil tank and no gas main, the WTGO (hot water) and SGO (steam) oil boilers reach 85–86% and 82–84% AFUE respectively. They are not condensing, so they still require a chimney or power vent — but they are among the few modern oil boilers with broad parts distribution.
Efficiency, Standards, and What the Numbers Actually Mean
- DOE minimum: Federal law requires new residential gas-fired hot water boilers to meet a minimum AFUE of 82% (80% for gas steam, 84–86% for oil). Any Weil-McLain model above those thresholds is compliant.
- ENERGY STAR: Gas hot water boilers rated at 90% AFUE or higher can carry the ENERGY STAR label. The Evergreen, ECO Tec, Ultra, AquaBalance, and GV90+ all qualify at their top ratings.
- ASME and ANSI: Cast-iron and commercial models are built to ASME Section IV and certified to ANSI Z21.13 / CSA 4.9. Ask your contractor for the AHRI certificate matching the exact model number — it documents the rated input and AFUE that rebate programs require.
- Venting and combustion air: Condensing units must be vented per the manufacturer’s instructions and NFPA 54. PVC vent runs, condensate neutralization, and combustion air openings are code items, not optional upgrades.
Real Operating Cost: 95% vs. 82% AFUE
Take a home that needs about 100 MMBtu of heat output per heating season (typical for a 2,000 sq ft house in Climate Zone 5):
- At 82% AFUE: about 1,220 therms of gas
- At 95% AFUE: about 1,053 therms of gas
- At $1.30 per therm: roughly $215 per year in savings, and more in colder climates or higher gas prices
Over 15 years, that gap is $3,000–$4,000 — which is why the price premium for condensing usually pays back, but rarely in under five years. Note that gas boilers generally do not qualify for the federal 25C tax credit (which covers heat pumps and biomass), so budget around utility and state rebates instead; many utilities pay $300–$1,500 for a 90%+ AFUE replacement, and some Northeast states add several thousand more.
How Much Does a Weil-McLain Boiler Cost?
Equipment alone runs roughly 55–65% of the total project. Here is a realistic US breakdown for a like-for-like replacement with no surprises:
| Cost Component | Typical Range |
|---|---|
| Equipment (condensing, 100–155 MBH) | $2,800–$5,500 |
| Labor (8–16 hours, two techs) | $1,200–$3,000 |
| Near-boiler piping, circulator, valves | $400–$1,200 |
| Venting (PVC kit or chimney liner) | $350–$1,500 |
| Condensate pump and neutralizer | $150–$400 |
| Permit and inspection | $100–$500 |
| Total installed | $4,500–$9,000 |
Add $800–$2,500 if the job requires asbestos abatement on old pipe insulation, a new gas line, electrical work for a new circuit, or removal of a cast-iron boiler from a basement (old sections can weigh 600–1,200 lbs). For a full line-item breakdown by region and fuel type, see our boiler cost breakdown.
What Drives the Price Up or Down
- Size: a 70 MBH Evergreen for a 1,400 sq ft house costs considerably less than a 220 MBH unit.
- Fuel conversion: switching from oil to gas adds a gas line, meter upgrade, and possibly a chimney liner — plan on $1,500–$4,000.
- System type: steam replacements cost 15–25% more because near-boiler piping, hartford loops, and header sizing take more labor.
- Combi vs. heat-only: an AquaBalance replaces both a boiler and a water heater, so compare it against the combined cost, not the boiler alone.
Reliability, Warranty, and Common Problems
Weil-McLain’s cast-iron products have an excellent reputation for longevity. Its condensing products are solid but more installation-sensitive — the majority of failures we see trace back to commissioning, water quality, or venting rather than the heat exchanger itself.
Warranty terms vary by model and by whether you are the original owner. Cast-iron residential models commonly carry a limited lifetime heat-exchanger warranty for the original purchaser, while condensing models typically offer 10–12 years on the heat exchanger and 5 years on parts. Always pull the specific warranty document for the exact model number — do not rely on the spec sheet summary.
The Five Most Common Weil-McLain Boiler Problems
- Condensate trap or drain line clogs (condensing models) — causes lockout, often flagged as a blocked-drain or pressure fault. Flushing the trap annually prevents it.
- Ignition lockout from a dirty flame sensor or rod — pulls the burner out of sequence and shuts the boiler down until reset.
- Low system pressure or air in the loop — the boiler will not fire reliably; usually a failing expansion tank, auto-fill, or air eliminator.
- Scale buildup in the heat exchanger — the leading killer of condensing boilers in hard-water areas. A water softener or periodic descale is cheaper than a new exchanger.
- Circulator pump failure — often the original pump reaching end of life at the same time as the boiler; replace it during the swap.
Error Codes and Troubleshooting
Evergreen and ECO Tec controls display fault codes and store a history, which is genuinely useful for diagnosis. The general categories are ignition faults, blocked flue or vent pressure faults, low water pressure/cutoff, sensor faults, and DHW sensor faults on combi units. A boiler that repeatedly locks out is telling you something is wrong with air, gas, water, or venting — not with the control board. Do not keep resetting a locked-out boiler; call a technician for a combustion analysis.
Maintenance, Sizing, and Expected Lifespan
- Annual service: $150–$300. Should include a combustion analysis, cleaning the condensate trap, checking gas pressure, verifying vent slope and terminations, and testing the relief valve and expansion tank.
- Water treatment: non-negotiable in hard water. Weil-McLain’s own manuals specify water chemistry limits for the fill water; ignoring them voids heat-exchanger coverage in many cases.
- Glycol systems: check pH and inhibitor levels every 2–3 years.
- Sizing: insist on a room-by-room Manual J load calculation. A modulating condensing boiler that is oversized will short-cycle and lose most of its efficiency advantage.
- Lifespan: 25–30 years for cast iron, 15–20 for condensing, with oil boilers often reaching 30 years when the burner is serviced annually.
Because condensing installations live or die on venting and piping details, the contractor matters more than the badge on the front of the boiler. Read our guide to boiler installation to see what a proper commissioning checklist should include before choosing a bid.
Weil-McLain Pros and Cons
Pros
- American-made, widely available parts and contractor familiarity
- Full coverage of gas, propane, oil, steam, and hot water
- Up to 95% AFUE with ENERGY STAR–qualified models
- Excellent cast-iron longevity and broad commercial support
- Good price-to-performance versus premium imported brands
Cons
- No heat-pump or hybrid offering for homeowners pursuing electrification
- Condensing models are installation-sensitive and demand water treatment in hard-water regions
- Warranty terms vary significantly by model and ownership status
- Controls and diagnostics are less app-centric than some competitors
Frequently Asked Questions
How much does a Weil-McLain boiler cost installed? Most US homeowners pay $3,500–$9,000 installed. A cast-iron CGi runs about $3,500–$6,500; an ECO Tec or Evergreen condensing unit runs $4,500–$9,000; an AquaBalance combi typically lands at $6,000–$10,000. Chimney liners, gas line upgrades, and abatement can add $800–$2,500.
How long does a Weil-McLain boiler last? Cast-iron models (CGi, GV90+, WTGO) commonly reach 25–30 years with annual service. Condensing models (Evergreen, ECO Tec, Ultra) generally last 15–20 years. In hard-water areas, the condensing boiler’s lifespan is largely determined by water treatment and periodic descaling.
Is Weil-McLain a good boiler brand? Yes. Weil-McLain has built boilers in the US since 1881, offers the broadest fuel and system-type coverage of the mainstream brands, and its condensing units reach 95% AFUE with ENERGY STAR recognition. The determining factor is a contractor who sizes the unit with a Manual J calculation and commissions it properly — that matters more than brand choice between Weil-McLain, Bosch, Navien, or Lochinvar.
Conclusion: Is a Weil-McLain Boiler Worth It?
For a US homeowner replacing an aging gas, oil, or steam boiler, Weil-McLain is one of the safest choices available: domestic manufacturing, near-universal parts availability, a 95% AFUE condensing lineup that qualifies for most utility rebates, and cast-iron products that routinely outlive their owners’ mortgages. The Evergreen is the best all-around pick for a gas hot-water retrofit, the CGi remains the workhorse for budget cast-iron replacements, and the WTGO/SGO keep oil-heated homes serviceable. Expect to invest $4,500–$9,000 installed for a condensing unit, and choose your installer on commissioning quality rather than the lowest bid — that decision determines whether you see the rated AFUE in your actual bills.
Ready to get real numbers for your home? Get matched with a licensed, insured local contractor who installs Weil-McLain equipment, request three itemized quotes with model numbers and AHRI certificates, and compare them line by line before you sign. In most markets you can have a written estimate in 24–48 hours — and locking in pricing before the heating season starts is the single easiest way to avoid paying emergency-replacement rates in January.