Weil-mclain 383-500-734 Ultra Series 4 105 Mbtu 94% Afue Natural Gas Condensing Water Boiler Direct Vent

Product Description

The WEIL-MCLAIN 383-500-734 is a high-efficiency condensing water boiler from the Ultra Series 4 lineup. It is designed for residential hydronic heating systems that demand reliable performance and fuel savings. This boiler delivers 105,000 BTU input with a 94% DOE AFUE rating, meaning it converts nearly all of its fuel into usable heat. HVAC technicians and heating contractors rely on this unit for new installations and retrofit projects where energy efficiency and precise control are top priorities. The boiler operates on natural gas or liquid propane, making it flexible for a wide range of job sites. It uses a direct vent configuration, drawing combustion air from outside and exhausting flue gases outdoors, which improves safety and installation versatility. The cast aluminum coated heat exchanger is built to withstand the condensing environment, where moisture from combustion gases is extracted to recover additional heat energy. The high-grade stainless steel burner runs quietly and modulates with a 5 to 1 turn-down ratio, allowing the boiler to match its output to actual heating demand rather than cycling on and off at full capacity. This modulation reduces wear on components and lowers fuel consumption over a heating season. The U-Control system is the brain of this boiler. It supports multiple setup and zone options, outdoor reset functionality, and domestic hot water priority. Technicians can manage temperature setpoints for up to three zones and even control multiple boilers from a single control panel. System sensing reads both supply temperatures and outdoor conditions to optimize performance automatically. On-screen service alerts and maintenance reminders help reduce callbacks and keep systems running efficiently. At 198 pounds, standing 47.75 inches tall and 22.8125 inches in length, this boiler fits within standard mechanical room footprints.

• 94% DOE AFUE condensing efficiency for maximum fuel savings in residential hydronic systems
• 5 to 1 modulating turn-down ratio reduces short cycling and extends equipment life
• U-Control system supports multi-zone setup, outdoor reset, domestic hot water priority, and multi-boiler management

Product Highlights

The WEIL-MCLAIN 383-500-734 Ultra Series 4 combines high-efficiency condensing technology with an intelligent control system, making it a dependable choice for residential hydronic heating installations that require precise zone management and low operating costs.

Product Information

Standard Information

• Brand: WEIL-MCLAIN
• Manufacturer Part Number: 383-500-734

Technical Specifications

• Series: Ultra S4
• Item Type: Boiler
• BTU Input: 105,000
• AFUE: 94%
• Fuel Type: Natural Gas / Liquid Propane
• Venting Type: Direct Vent
• Boiler Type: Residential
• Material: Aluminum
• Height: 47.75 inches
• Length: 22.8125 inches
• Weight: 198 pounds