Ultra^®
Gas Boiler Series 4

The Weil‑McLain Ultra® Gas Boiler Series 4 delivers effortless comfort with maximum efficiency. Engineered with a state‑of‑the‑art, nano‑coated cast aluminum heat exchanger, the Ultra Series 4 helps reduce buildup while maintaining up to 94% AFUE efficiency. Designed for quiet operation, flexible system control, and reliable performance, this high‑efficiency condensing boiler is ideal for residential and light commercial applications where comfort, energy savings and long‑term durability matter most.

Features

DURABLE DESIGN

Cast aluminum coated heat exchanger; High grade stainless steel burner features quiet operation

HIGH EFFICIENCY

Up to 94% DOE AFUE efficiency

EXTENDED WARRANTY

5 Years Extended Warranty on service parts with boiler registration (Must be within 90 days of installation, residential only.)

SYSTEM SENSING

Sense boiler, system and outdoor temperatures

MULTIPLE BOILERS

Capable of controlling additional boilers or heating appliances

TEMPERATURE MANAGEMENT

From 1 to 3 different setpoints
for single or multiple zone
type management

Additional Highlights

Designed to operate in low temperature condensing applications
Outdoor reset and domestic hot water priority
Modulates with 5:1 turn-down ratio
U-Control gives you the power for easy set-up and maintenance:
- Multiple set-up and zone options
- System sensing recognizes system and outdoor temperatures
- Temperature management for up to three different set-points
- Control multiple boilers from a single control panel
- Standard screen messages provide service alerts and maintenance reminders

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big on warmth, low on energy use

Engineered for comfort, designed for efficiency

Certified ENERGY STAR® and heat pump ready, this high-efficiency boiler delivers powerful, eco-friendly performance while keeping energy costs low.

Technical Specs

MODEL	AFUE (%)	CSA INPUT (MBH)	NET (MBH)	DOE HEATING CAP. (MBH)	VENT SIZE (IN.)
ULTRA-80	93.5	80	62	71	2″ or 3″
ULTRA-105	94	105	82	94	2″ or 3″
ULTRA-155	94	155	121	139	3″
ULTRA-230	94.1	230	180	207	3″ or 4″
ULTRA-299	92.5	299	235	270	4″
ULTRA-399	91.7*	399	317	364*	4″