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Bosch Greenstar Combi 151P - 134K BTU - 95.0% AFUE - Combi Gas Boiler - Direct Vent
Model:
ZWB42-3A
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Features
- Condensing Technology Improves Efficiency
- The ZWB42-3A 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 represents today's best efficiency technologies brought 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. This boiler includes a domestic hot water coil, allowing the boiler to act as a tankless hot water heater as well as a hydronic boiler.
Product Note
Please note the ZWB42-3A does not include an expansion tank or controller.
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
ZWB42-3A
Overview
Product Category
Boiler
Additional Model Numbers
ZWB42-3, ZWB42-3A
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.
Yes
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
4500 Feet
Assembly Type
Packaged
Includes Pump
Yes
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.
151600 BTU
Minimum Input Capacity
36000 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.
134400 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.
117000 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
Cold Water Inlet
3/4 Inch
Hot Water Outlet
3/4 Inch
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
110.2 Pounds
Shipping Weight
118 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
(6)
Bosch Thermotechnology ZWB42-3A Reviews & Ratings
Bosch claims the title of 'World's best-selling condensing gas boiler' with the Greenstar. The Greenstar Combi, which provides domestic hot water in addition to space heat, is easy to recommend. Showing great confidence in their product, Bosch ships it with an amazing 5-year parts & labor warranty. It also has an included expansion tank, an outdoor reset control, and an integrated Grundfos 3-speed pump. As for flexibility, the Greenstar ships with a conversion kit for LP gas. It also accommodates applications up to 6,000 ft altitude without de-rating output (except 151 models).
Was this review helpful?
Rating Breakdown
5/5
5/5
5/5
5/5
So Far So Good
By William M
Connecticut
Purchased 02/01/2024 |
Review Posted 03/01/2024
The installation manual leaves a lot to be desired. We will have to wait and see about reliability.
Was this review helpful?
Rating Breakdown
4/5
4/5
4/5
4/5
Great Product, No Issues
By Mark S
LANSDALE, Pennsylvania
Purchased 08/13/2020 |
Review Posted 09/18/2020
I've used my Bosch for three years with no issues. I used this unit to replace my old oil fired boiler. I installed the optional outdoor temperature sensor which allows the unit so modulate the hot water temperature based on outdoor temperature. I highly recommend that option to get the most savings and best overall comfort. When the outdoor temp is above a certain value, the units sends warm water to the heaters, which is nice, because it doesn't quickly overheat the space. I recently had to replace this unit no fault of Bosch, but thanks to my basement flooding in that storm this summer. I bought another matching unit!! This unit produces domestic hot water also, but keep in mind it does one or the other, but not both at the same time like a water storage boiler. So if you have a large family, who take long showers or have tons of laundry, it won't produce heating hot water while it is making domestic hot water. Wasn't an issue for me, but I don't live in a super cold region (worst winter temp is around -10degees).
Mark S Recommends This
Was this review helpful?
Rating Breakdown
4/5
5/5
5/5
4/5
Pros:
Quiet, Reliable, High Quality, Id Buy It Again
Cons:
Expensive
Good Product
By Kaler B.
Wallace, Kansas
Purchased 11/07/2017 |
Review Posted 01/10/2018
I've been running this unit for a couple of weeks now and everything seems to be in good working and running order. It is extremely quiet and I really have to listen to even hear it run. I am not using the domestic hot water option on this boiler, only as a boiler for radiant heat & am very pleased with it thus far.
Kaler B. Recommends This
Was this review helpful?
Rating Breakdown
5/5
5/5
5/5
4/5
Super efficient heat source
By George T.
Adams, Massachusetts
Purchased 08/22/2017 |
Review Posted 01/10/2018
This is a fantastic boiler and my son has been operating his for 8 years trouble free. The only thing I might recommend is getting a better thermostat then the one they send. Small thing but I might upgrade for next season. Thermostats have entered a new era and this boiler can utilize the tech.
George T. Recommends This
Was this review helpful?
Rating Breakdown
5/5
5/5
5/5
5/5
combi 151
By Van P.
Yonkers, New York
Review Posted 01/16/2016
My contractor purchased the 151 combi from local warehouse. I just wanted to share experiences for the whole deal of getting this one.
I had it installed a few days ago by a local contractor who claimed certified by Bosch. Technicians under supervision by certified plumber were struggling of how they were going to install and had it fired, back and fort with rewiring, and reconnect piping for a few occasions, saying they were difficult to install. Two vents with about 3-4 inches diameters needed to be direct to out side wall of the house, meaning that they have to make 2 big holes to out side, then, lining straight from the boiler, cannot be bent or using elbows for cosmetic purposes due to possible alteration of efficiency. So, you need to know before doing it. First day the temperature was uncontrolled too hot, to 90-100 degree in home. We had to open windows. They came back, checked the wiring in the boiler and thermostat. The third day, the technician changed cable from boiler to thermostat for $450. It works well and more accurate with temperature regulation.
The boiler has been very quiet and well kept on the wall, giving me more space in the basement. I was told not to touch the screen except had to turn off boiler for any reasons. When turned on need to push reset icon only.
It cost total of about $12,000 including an installation of one vent port on my existing heating pipe ($450). They had worked every day from removal of the old boiler to completion of the new one for a week! Great!
Also, I got the pressure expansion for no charge!
I had it installed a few days ago by a local contractor who claimed certified by Bosch. Technicians under supervision by certified plumber were struggling of how they were going to install and had it fired, back and fort with rewiring, and reconnect piping for a few occasions, saying they were difficult to install. Two vents with about 3-4 inches diameters needed to be direct to out side wall of the house, meaning that they have to make 2 big holes to out side, then, lining straight from the boiler, cannot be bent or using elbows for cosmetic purposes due to possible alteration of efficiency. So, you need to know before doing it. First day the temperature was uncontrolled too hot, to 90-100 degree in home. We had to open windows. They came back, checked the wiring in the boiler and thermostat. The third day, the technician changed cable from boiler to thermostat for $450. It works well and more accurate with temperature regulation.
The boiler has been very quiet and well kept on the wall, giving me more space in the basement. I was told not to touch the screen except had to turn off boiler for any reasons. When turned on need to push reset icon only.
It cost total of about $12,000 including an installation of one vent port on my existing heating pipe ($450). They had worked every day from removal of the old boiler to completion of the new one for a week! Great!
Also, I got the pressure expansion for no charge!
Van P. Recommends This
Was this review helpful?
Rating Breakdown
5/5
5/5
5/5
4/5
Pros:
Features, Quiet, Light Weight, High Quality
Cons:
Expensive
Product Q&A
(2)
Product Questions
Answered by Ken, the eComfort Product Expert
Can this unit be retrofitted to use propane gas?
John McNew
from New Mexico
May 31, 2016
What would be the appropriate pressure setting for the relief valve?
Angie
from New York
September 09, 2015
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Bosch Greenstar Combi 151P - 134K BTU - 95.0% AFUE - Combi Gas Boiler - Direct Vent
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