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Williamson-Thermoflo FS-120 COMBI
Williamson-Thermoflo FS-120 COMBI
Williamson-Thermoflo FS-120 COMBI
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Williamson-Thermoflo FS-120 COMBI
Williamson-Thermoflo FS-120 COMBI
Williamson-Thermoflo FS-120 - 109K BTU - 92.2% AFUE - Combi Gas Boiler - Direct Vent
Model: FS-120 COMBI
3.7 out of 53.7 out of 53.7 out of 53.7 out of 53.7 out of 5
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$2,289.00
Was $2,439.00
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*This product qualifies for Free Shipping anywhere in the contiguous US. Accessories may ship separately. Items over 100lbs shipped via semi-truck, be sure to select "Lift Gate" to lower the product to the ground curbside. Remote area surcharges may apply, see our full shipping policy for more details.
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  • Lift Gate Service Available - Free Lift Gate Learn More
*We currently CANNOT ship this product to California or any destination outside of the United States
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FREE
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Lift Gate Service
All products weighing more than 100 lbs. ship via semi-truck. We recommend ordering the Lift Gate Service to safely lower the product to the curb. If you have a loading dock or forklift, you do NOT need a Lift Gate service. If you are a residential customer, you must have at least 2-4 able-bodied people present to unload the product. Learn More
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  • Product Description
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  • 2
    Product Q&A
  • Recommended Accessories
  • How-To Articles
  • Manuals
Product Description
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Features
Features
    Keep your home warm and heating costs low with the Williamson-Thermoflo Freestyle combi-boiler. The Freestyle FS-120 COMBI boasts an impressive 92.2% AFUE efficiency rating, making it one of the most efficient boilers on the residential market. Easy to install and even simpler to maintain, the Freestyle boiler comes with a wall mount allowing it to fit into almost any space with its compact design. A crystal clear digital display allows for easy access to important information as well as the ability to quickly and easily adjust any of the boilers settings. The FS-120 COMBI comes standard with multiple features designed to keep energy costs down, including its modulating combustion system, allowing the FS-120 COMBI to run reliably while saving you money. As a Combi model, this boiler comes with a built in domestic hot water heater and circulator pump, allowing it to provide endless hot water to your showers, sinks, and home appliances. The Freestyle series runs standard on natural gas, but can be converted to propane with a simple adapter, making it flexible enough to be used in any home.
  • Higher Efficiency, Lower Costs
  • With an AFUE efficiency rating above 92%, the Freestyle boiler is one of the most efficient on the market. With its ASME rated heat exchanger and modulating burner, it will not only lower energy costs, but help reduce your carbon footprint as well.
  • Factory Tested
  • All Freestyle boilers come factory tested and certified by top industry analysts ensuring they will remain reliable and efficient for years to come.
  • Unmatched Flexibility
  • Each Freestyle comes with its own wall mounting kit. Combined with the boiler's compact design and multiple venting options, the Freestyle boiler can fit into nearly any residential space.
  • Built in Hot Water Heater
  • The Freestyle Combi models come with a built in tankless water heater. Using its built-in flat plate heat exchanger, the Freestyle Combi unit can provide hot water for your entire home.
  • Product Includes
  • (1) FS-120 COMBI Freestyle Boiler
  • (1) 640-000-044WT Wall-Mount Kit
  • (1) 640-000-037WT Condensate Trap Kit
  • (1) 640-000-017WT FX3-FP Circulator
Specifications
General Information
Product Line
Freestyle
Medium Learn More
Medium
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
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.
Natural Gas
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.
Condensing
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.
Direct 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.
Yes
Modulating/Staging Learn More
Modulating/Staging
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
Modulating
Mount Type
Wall
Minimum Altitude
0 Feet
Maximum Altitude
10000 Feet
Includes Pump
Yes
Assembly Type
Packaged
Gas Conversion Kit
Available
UPC
811175015542
Performance
AFUE Learn More
AFUE
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
92 %
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.
120000 BTU
Minimum Input Capacity
12000 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.
109000 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.
94000 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
Yes
Turndown Ratio
10:1
Electrical Data
Phase
1
Frequency
60 Hz
Dimensions
Flue Connection Size
3 Inches
Gas Connection Size
1/2 Inch
Supply Connection
3/4 Inch
Return Connection
3/4 Inch
Product Height
23 5/8 Inches
Product Width
15 3/4 Inches
Product Depth
12 29/48 Inches
Product Weight
77 Pounds
Shipping Weight
87 Pounds
Certifications
Energy Star Listed
Yes
ETL Listed
Yes
ASME Certified
Yes
AHRI Certified
Yes
ISO Certified
Yes
AHRI Reference Number
7470130
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
2 Years
Heat Exchanger Warranty
10 Years
Features
Features
    Keep your home warm and heating costs low with the Williamson-Thermoflo Freestyle combi-boiler. The Freestyle FS-120 COMBI boasts an impressive 92.2% AFUE efficiency rating, making it one of the most efficient boilers on the residential market. Easy to install and even simpler to maintain, the Freestyle boiler comes with a wall mount allowing it to fit into almost any space with its compact design. A crystal clear digital display allows for easy access to important information as well as the ability to quickly and easily adjust any of the boilers settings. The FS-120 COMBI comes standard with multiple features designed to keep energy costs down, including its modulating combustion system, allowing the FS-120 COMBI to run reliably while saving you money. As a Combi model, this boiler comes with a built in domestic hot water heater and circulator pump, allowing it to provide endless hot water to your showers, sinks, and home appliances. The Freestyle series runs standard on natural gas, but can be converted to propane with a simple adapter, making it flexible enough to be used in any home.
  • Higher Efficiency, Lower Costs
  • With an AFUE efficiency rating above 92%, the Freestyle boiler is one of the most efficient on the market. With its ASME rated heat exchanger and modulating burner, it will not only lower energy costs, but help reduce your carbon footprint as well.
  • Factory Tested
  • All Freestyle boilers come factory tested and certified by top industry analysts ensuring they will remain reliable and efficient for years to come.
  • Unmatched Flexibility
  • Each Freestyle comes with its own wall mounting kit. Combined with the boiler's compact design and multiple venting options, the Freestyle boiler can fit into nearly any residential space.
  • Built in Hot Water Heater
  • The Freestyle Combi models come with a built in tankless water heater. Using its built-in flat plate heat exchanger, the Freestyle Combi unit can provide hot water for your entire home.
  • Product Includes
  • (1) FS-120 COMBI Freestyle Boiler
  • (1) 640-000-044WT Wall-Mount Kit
  • (1) 640-000-037WT Condensate Trap Kit
  • (1) 640-000-017WT FX3-FP Circulator
Specifications
General Information
Product Line
Freestyle
Medium Learn More
Medium
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
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.
Natural Gas
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.
Condensing
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.
Direct 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.
Yes
Modulating/Staging Learn More
Modulating/Staging
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
Modulating
Mount Type
Wall
Minimum Altitude
0 Feet
Maximum Altitude
10000 Feet
Includes Pump
Yes
Assembly Type
Packaged
Gas Conversion Kit
Available
UPC
811175015542
Performance
AFUE Learn More
AFUE
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
92 %
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.
120000 BTU
Minimum Input Capacity
12000 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.
109000 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.
94000 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
Yes
Turndown Ratio
10:1
Electrical Data
Phase
1
Frequency
60 Hz
Dimensions
Flue Connection Size
3 Inches
Gas Connection Size
1/2 Inch
Supply Connection
3/4 Inch
Return Connection
3/4 Inch
Product Height
23 5/8 Inches
Product Width
15 3/4 Inches
Product Depth
12 29/48 Inches
Product Weight
77 Pounds
Shipping Weight
87 Pounds
Certifications
Energy Star Listed
Yes
ETL Listed
Yes
ASME Certified
Yes
AHRI Certified
Yes
ISO Certified
Yes
AHRI Reference Number
7470130
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
2 Years
Heat Exchanger Warranty
10 Years
Product Specs
+
Specifications
General Information
Product Line
Freestyle
Medium Learn More
Medium
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
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.
Natural Gas
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.
Condensing
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.
Direct 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.
Yes
Modulating/Staging Learn More
Modulating/Staging
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
Modulating
Mount Type
Wall
Minimum Altitude
0 Feet
Maximum Altitude
10000 Feet
Includes Pump
Yes
Assembly Type
Packaged
Gas Conversion Kit
Available
UPC
811175015542
Performance
AFUE Learn More
AFUE
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
92 %
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.
120000 BTU
Minimum Input Capacity
12000 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.
109000 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.
94000 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
Yes
Turndown Ratio
10:1
Electrical Data
Phase
1
Frequency
60 Hz
Dimensions
Flue Connection Size
3 Inches
Gas Connection Size
1/2 Inch
Supply Connection
3/4 Inch
Return Connection
3/4 Inch
Product Height
23 5/8 Inches
Product Width
15 3/4 Inches
Product Depth
12 29/48 Inches
Product Weight
77 Pounds
Shipping Weight
87 Pounds
Certifications
Energy Star Listed
Yes
ETL Listed
Yes
ASME Certified
Yes
AHRI Certified
Yes
ISO Certified
Yes
AHRI Reference Number
7470130
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
2 Years
Heat Exchanger Warranty
10 Years
Reviews
(3)
+
Williamson-Thermoflo FS-120 COMBI Reviews & Ratings
Product Q&A
(2)
+
Search Product Q&A's Answered by Bob, the Heating Product Expert
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Is this a direct hot water heater or an indirect? And will I need a hot water holding tank?
Mark 
from Pennsylvania 
December 22, 2015
Answer
The Williamson-Thermoflo Freestyle boilers heat water for domestic use directly and do not require any external heat exchangers or storage tanks. You can, however, add a storage tank to the domestic hot water side to act as a buffer to improve hot water availability during peak demand.
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Will the Freestyle work with two heating zones?
David 
from Connecticut 
December 03, 2015
Answer
The Freestyle boiler can work with multiple heating zones, either with zone valves or circulators. You will likely need a separate zone controller. For more details, please reference pages 41-43 of the manual.

For help choosing a zone controller, feel fee to call us as 866-554-4328.
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