Williamson-Thermoflo GWI-047-L-T-S2
Williamson-Thermoflo GWI-047-L-T-S2
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Williamson-Thermoflo GWI-047 - 40K BTU - 83.0% AFUE - Hot Water Propane Boiler - Power Vent



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Williamson-Thermoflo GWI-047 - 40K BTU - 83.0% AFUE - Hot Water Propane Boiler - Power Vent
Williamson-Thermoflo GWI-047 - 40K BTU - 83.0% AFUE - Hot Water Propane Boiler - Power Vent
Model: GWI-047-L-T-S2
Was $1,899.00
Product Discontinued
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Recommended Accessories

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Expert Recommended Accessories Selected by Bob, our Expert
Required Accessories 9
These accessories are required to properly setup/install this product.
Optional Accessories 10


    "Uncover warm possibilities" with Williamson-Thermoflo's GWI Gas Water Induced-Draft boiler. The highly efficient GWI-047-L-T-S2 pumps out 47,000 BTUs with an AFUE (annual fuel utilization efficiency) rating of 83.0 percent. Not only is the GWI efficient, but it is also versatile with the induced-draft design that allows for chimney or sidewall venting. This factory-packaged boiler has many features; like a compact design, cast-iron sections with built-in air separator, hot surface ignition system, and an insulated heavy-gauge steel jacket. The GWI is also easily serviced with all controls in reach, color-coded wiring, and a one-piece access door. Since it is factory tested and comes with a limited lifetime warranty, you can be absolutely sure that your investment is reliable and built to last.
  • Factory Tested
  • GWI boilers are factory tested, ensuring reliability and properly functioning equipment.
  • Easy Service
  • With all controls in reach, one-piece access door, and color-coded wiring, servicing the GWI boiler easy.
  • Limited Lifetime Warranty
  • A limited lifetime warranty on the heat exchanger means that you can rest assured that your investment is covered, should there be a problem.
  • Multiple Venting Options
  • Induced-draft design provides you with many options for your boiler by allowing for sidewall or chimney venting.
  • Compact Design
  • GWI's compact design allows for installation is tight or small spaces.
  • Product Includes
  • Taco 007 Circulator Pump


specs product image PID-31066
Product Category
General Information
Product Line
Product Category
Medium Learn More
Medium refers to the substance that carries heat through the heating system. Systems are either designed to use either Hot Water or Steam as a medium, and components are usually specific to one or the other.
Hot Water
Heat Exchanger Material
Cast Iron
Fuel Type Learn More
Fuel Type
To create heat, some form of fuel is required. Fuel Type specifies what the product uses as an input to create heat.
Liquid Propane
Combustion Type Learn More
Combustion Type
Condensing appliances use leftover thermal energy from combustion gases to heat water in a secondary heat exchanger, resulting in higher efficiency and lower exhaust temperature.
Vent Type Learn More
Vent Type
Products that use combustion (burning) of fuel to create heat also create potentially dangerous gasses that need to be exhausted (AKA "Vented"). Depending on the product, venting can be done via a chimney, through a side wall, or use a second vent to provide fresh air to the appliance.
Power Vent
DHW Production Learn More
DHW Production
DHW (Domestic Hot Water) is potable water for uses other than space heat. Some boilers are able to provide DHW "out of the box", while others can do so with the purchase of optional accessories.
Modulating/Staging Learn More
Stages are unique speeds or levels that equipment can operate at. More stages allow for better fine-tuned control of output, which improves comfort and efficiency. Modulating equipment can operate across a range of levels, giving the highest level of fine-tuned control. Learn More
Mount Type
Minimum Altitude
0 Feet
Maximum Altitude
2000 Feet
Assembly Type
Includes Pump
AFUE Learn More
AFUE (Annual Fuel Utilization Efficiency) measures the efficiency of combustion equipment over the entire heating season, and is calculated by dividing the amount of energy that is actually heating your home by the total energy contained in the fuel used by the boiler/furnace. Learn More
83 %
Maximum Input Capacity Learn More
Maximum Input Capacity
The Maximum Input Capacity describes how quickly the appliance will use fuel when delivering it's maximum capacity. The units may change depending on the fuel being used.
47500 BTU
DOE Heating Capacity Learn More
DOE Heating Capacity
Also referred to as Gross Output, this is the output of a boiler after accounting for combustion efficiency. We recommend sizing hot water boilers based on the DOE Heating Capacity.
40000 BTU
Net I=B=R Capacity Learn More
Net I=B=R Capacity
I=B=R, also referred to as Net Output or AHRI Capacity, is the rated heat output of a boiler after accounting for combustion efficiency, piping loss, and an extra pickup factor. We recommend sizing steam boilers based on the I=B=R rating.
35000 BTU
Ultra Low NOx Emissions Learn More
Ultra Low NOx Emissions
NOx is a byproduct of the combustion process, and it's output is regulated in some jurisdictions. Many regulators mirror SCAQMD rules, which regulate air quality for some parts of Southern California. Ultra Low NOx appliances emit less than 10-14 ng/J (nanogram per Joule) of NOx. Learn More
Electrical Data
60 Hz
Flue Connection Size
3 Inches
Gas Connection Size
1/2 Inch
Supply Connection
1 1/4 Inches
Return Connection
1 1/4 Inches
Product Height
28 3/8 Inches
Product Width
19 Inches
Product Depth
23 1/4 Inches
Product Weight
190 Pounds
Shipping Weight
200 Pounds
Warranty Information
Parts Warranty Learn More
Parts Warranty
A warranty is a safeguard from defects in manufacturing and can vary in length and terms. To see the manufacturer's warranty statement, click on the Manuals tab. Learn More
1 Year
Heat Exchanger Warranty
Lifetime Years


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