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Bosch Greenstar 79 - ZBR21 - 71K BTU - 95.0% AFUE - Hot Water Gas Boiler - Direct Vent
Model:
ZBR21-3
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Recommended Accessories
Expert Recommended Accessories
Selected by Ken, our Expert
Required Accessories
9
These accessories are required to properly setup/install this product.
Optional Accessories
10
Features
- Condensing Technology Improves Efficiency
- The ZBR21-3 is a condensing boiler, using the leftover energy in the boiler's flue exhaust to further heat your home. Keep your home warmer for less energy cost!
- Fully Modulating Fan
- The boiler includes a fully modulating fan to control the boiler's burning rate, allowing optimum efficiency to be achieved during a wide variety of outdoor conditions.
- Small Size and Low Installation Clearances
- Low installation clearances on all sides, wall mounting configuration, and small footprint translate into a boiler that can be installed almost anywhere.
The Bosch Greenstar boiler brings today's high efficiency technologies together in a single package. Astounding efficiency ratings can be achieved with the use of Bosch's condensing technology, squeezing every last BTU out of your home's gas supply. An included 3-speed Grundfos pump and a wide variety of pipe venting options allow the boiler to be installed in nearly any home imaginable.
California residents see
Warning: This product can expose you to chemicals including Lead which is known to the State of California to cause Developmental Harm.
For more information go to: www.p65Warnings.ca.gov
Specifications
ZBR21-3
Overview
Product Category
Boiler
General Information
Product Line
Greenstar
Product Category
Boiler
Medium
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
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
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
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
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.
No
Modulating/Staging
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
6000 Feet
Includes Pump
Yes
Assembly Type
Packaged
Gas Conversion Kit
Included
Performance
AFUE
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
95 %
Maximum Input Capacity
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.
79200 BTU
Minimum Input Capacity
23900 BTU
DOE Heating Capacity
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.
71000 BTU
Net I=B=R Capacity
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.
62000 BTU
Ultra Low NOx Emissions
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
5:1
Electrical Data
Phase
1
Frequency
60 Hz
Dimensions
Gas Connection Size
3/4 Inch
Flue Connection Size
3 Inches
Supply Connection
1 Inch
Return Connection
1 Inch
Product Height
33 1/2 Inches
Product Width
17 19/48 Inches
Product Depth
13 43/48 Inches
Product Weight
103.6 Pounds
Shipping Weight
103.6 Pounds
Certifications
Country of Origin
United States
CSA Listed
Yes
ASME Certified
Yes
AHRI Certified
Yes
Warranty Information
Parts Warranty
Parts Warranty
A warranty is a safeguard from defects in manufacturing and can vary in length and terms. Some manufacturers require registration for extended warranty benefits, be sure to check out features and the warranty document. To see the manufacturer's warranty statement, click on the Manuals tab. Learn More
5 Years
Heat Exchanger Warranty
Limited Lifetime Years
Reviews
(2)
Bosch Thermotechnology ZBR21-3 Reviews & Ratings
Product Q&A
(1)
Product Questions
Answered by Ken, the eComfort Product Expert
I am at an altitude of 6500 ft. This unit says max 6000. Can I still use it with just less efficiency or can you recommend another similar unit? I need heat only for an in-floor radiant system.
Glenn M.
from Connecticut
October 26, 2016
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Bosch Greenstar 79 - ZBR21 - 71K BTU - 95.0% AFUE - Hot Water Gas Boiler - Direct Vent
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