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Weil-McLain AquaBalance™ WMB-155C - 143K BTU - 94.4% AFUE - Combi Gas Boiler - Direct Vent
Model:
383100000
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Recommended Accessories

Expert Recommended Accessories
Selected by Ken, our Expert
Optional Accessories
12
$65.00
In-Stock
Model: PPKIT-3HC-78
Maximum Straight Run (Inches)
$374.00
$59.00
In-Stock
$101.00
Factory-Direct
Model: 383500350
$110.00
In-Stock
Model: 383500397
$83.00
Only 2 In-Stock
Model: 382200430
$156.00
$99.00
Model: 383500631
$129.00
In-Stock
$159.00
Factory-Direct
Model: PPKIT-3VC-42
Maximum Straight Run (Inches)
$518.00
Model: PPKIT-3HT-42
Maximum Straight Run (Inches)
$345.00
Features
- High Efficiency Heating and Hot Water
- Weil-McLain's rigorous standards of boiler efficiency are clearly shown in the AquaBalance™ Combi line. The WMB-155C combines space heating and domestic hot water production, boasting an impressive 94.4% AFUE rating without compromising performance.
- Easy Installation
- The AquaBalance™ comes pre-wired with a plug-in ready electrical design. Fewer pipes and connection points streamline the installation process, allowing you to get the system up and running quickly.
- Compact Design
- The AquaBalance's™ compact design is small enough to fit in a closet; a perfect solution for families living in smaller homes or apartments. It also features a heavy gauge insulated jacket to provide extremely quiet operation.
- Outdoor Reset Control
- An outdoor reset sensor is included with every AquaBalance™ boiler. This sensor allows your boiler temperature to be adjusted relative to the temperature outside, eliminating excess energy use and guaranteeing comfort.
- Contractor Friendly
- Along with simple installation, the AquaBalanace™ also features removable sides panels. This makes all of the internal components very accessible, allowing for quick and easy service.
- Product Includes
- (1) Weil-McLain AquaBalance™ WMB-155C Hot Water Boiler
- (1) Outdoor Temperature Sensor
- (1) Mounting Bracket & Hardware
- (1) 3-in-1 Vent Adapter
- (1) 3-Speed Circulator
Over the last 130 years, Weil-McLain has built a reputation of designing some of the most reliable boilers in the marketplace. Their dedication to producing long-lasting heating solutions is seen in every boiler they make. Weil-McLain's AquaBalance™ Combi hot water boiler is a highly efficient and reliable solution to both space heating and domestic hot water needs. Using condensing technology, the AquaBalance™ will reuse heat that escapes from conventional boilers, providing greater efficiency. Simple design along with Honeywell® controls make the AquaBalance™ easy to install and easy to use. With a 94.4% AFUE, Low Nox certification, and a 10:1 turndown ratio, the AquaBalance™ WMB-155C makes comfort and efficiency more accessible than ever before.
Product Note
Compatible NG to LP Conversion Kit: Weil-McLain 640-000-083
California residents see
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.
For more information go to: www.p65Warnings.ca.gov
Specifications
383100000

General Information
Product Line
AquaBalance
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
10000 Feet
Includes Pump
Yes
Assembly Type
Packaged
Gas Conversion Kit
Optional
UPC
0672619206977
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
94 %
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.
155000 BTU
Minimum Input Capacity
15500 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.
143000 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.
124000 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
Low NOx Emissions
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. Low NOx appliances emit less than 40 ng/J (nanogram per Joule) of NOx. Learn More
Yes
Turndown Ratio
10:1
Electrical Data
Voltage
120 Volts
Phase
1
Frequency
60 Hz
Dimensions
Flue Connection Size
3 Inches
Gas Connection Size
1/2 Inch
Cold Water Inlet
3/4 Inch
Hot Water Outlet
3/4 Inch
Boiler Supply
1 Inch
Boiler Return
1 Inch
Product Height
27 9/16 Inches
Product Width
16 13/24 Inches
Product Depth
12 29/48 Inches
Shipping Weight
87 Pounds
Certifications
CSA Listed
Yes
Energy Star Listed
Yes
ASME Certified
Yes
AHRI Certified
Yes
AHRI Reference Number
9964003
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
2 Years
Heat Exchanger Warranty
10 Years
Reviews
(10)
Weil-McLain 383100000 Reviews & Ratings
Customer Photos and Videos






Customer Rating
4.90
(10 Ratings)
77% recommend this product
5
(9)

4
(1)

3
(0)

2
(0)

1
(0)


awsome aqua balance, this combi is as good as they come
By Theo H.
Cohoes, New York
Purchased 10/25/2019 |
Review Posted 11/23/2019
none better than this one!!
Theo H. Recommends This
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Rating Breakdown
5/5
5/5
5/5
5/5

great boiler
By Nicholas B.
Machias, New York
Purchased 10/31/2019 |
Review Posted 11/22/2019
The boiler was very light weight, well built and easy to hang. I was surprised at how fast the water heated.
Nicholas B. Recommends This
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Rating Breakdown
5/5
5/5
5/5
5/5

Great price. Works as expected.
By Richard V.
Marietta, Ohio
Purchased 10/06/2019 |
Review Posted 11/07/2019
So far very pleased with this product.
Richard V. Recommends This
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Rating Breakdown
4/5
3/5
3/5
5/5
Great product so far
By Jeffrey C.
Fort Collins, Colorado
Review Posted 10/21/2019
Just purchased and installed on of these units (LP). The unit appears to be very uncomplicated (streamlined interior mechanical/electrical). Easy to install, easy to hook up, easy to start up. This is practically a plug and play unit. Its only been up and running a few days so no comment on reliability - but its super quiet and kicks out plenty of hot water. I highly recommend. Shipped in durable packaging.
Jeffrey C. Recommends This
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Rating Breakdown
5/5
5/5
5/5
5/5

Minnesota Winter
By Raymond M
Hastings, Minnesota
Purchased 07/26/2018 |
Review Posted 04/23/2019



We have now used the WMB-155C through one Minnesota winter - it was a long and cold one even by our standards. We have been happy with how stable temperatures are while showering and how quickly domestic water arrives even without a tank of hot water standing by.
We replaced an older cast iron boiler from Weil-McClain that must have been over 20 years old. It was starting to leak in the cast iron exchanger. We stuck with WM because we were always able to get parts, even the control board.
The internal three way valve did fail at about 5 months after a very cold spell where the boiler ran almost without stop for a week. Maybe it got hot? Since I self-installed I had difficulty getting warranty coverage even though I had it inspected and verified by an authorized dealer. (I was a plumber years ago.)
The fittings in the boiler are sealed with fiber gaskets which means that you aren't cranking on things. It also means that they can easily loosen. Because of this (and the overhanging front panel) I recommend putting nipple extensions on all the connection points at the bottom of the unit so that it is easier to reach connections with wrenches.
The programming takes a little thinking through but affords some nice efficiency gains once you sort it out. The wiring also allows a lot of ways to connect the system, which provides a lot of flexibility.
It is a small unit and I took advantage of that to fit it in a very tight space and recover room in my utility closet (my wife loved that.) The Webstone combo valve saved a lot of hassle and space.
We replaced an older cast iron boiler from Weil-McClain that must have been over 20 years old. It was starting to leak in the cast iron exchanger. We stuck with WM because we were always able to get parts, even the control board.
The internal three way valve did fail at about 5 months after a very cold spell where the boiler ran almost without stop for a week. Maybe it got hot? Since I self-installed I had difficulty getting warranty coverage even though I had it inspected and verified by an authorized dealer. (I was a plumber years ago.)
The fittings in the boiler are sealed with fiber gaskets which means that you aren't cranking on things. It also means that they can easily loosen. Because of this (and the overhanging front panel) I recommend putting nipple extensions on all the connection points at the bottom of the unit so that it is easier to reach connections with wrenches.
The programming takes a little thinking through but affords some nice efficiency gains once you sort it out. The wiring also allows a lot of ways to connect the system, which provides a lot of flexibility.
It is a small unit and I took advantage of that to fit it in a very tight space and recover room in my utility closet (my wife loved that.) The Webstone combo valve saved a lot of hassle and space.
Raymond M Recommends This
Was this review helpful?
Rating Breakdown
5/5
4/5
5/5
5/5
Pros:
Quiet, Price, Features, I'd Buy It Again
Great product
By Ned K.
New Bremen, Ohio
Review Posted 10/14/2018
Had some issues at first but now we Love it
Ned K. Recommends This
Was this review helpful?
Rating Breakdown
5/5
5/5
5/5
5/5

Great Replacement!
By Scott Z.
Washingtonville, New York
Purchased 02/25/2018 |
Review Posted 03/19/2018
We replaced our heating system this past winter. We have been so happy and warm!
Scott Z. Recommends This
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Rating Breakdown
4/5
5/5
5/5
5/5

Great Value and Performance
By Alex V.
Amherst, Ohio
Purchased 12/22/2017 |
Review Posted 02/28/2018

I had planned to buy the Bosch Greenstar 151 combi unit (which I hear is a great unit) until I found this Weil Mclain Aquabalance 155C. It has a higher DOE heating capacity and a better turn down ratio, but a slightly lower AFUE.
The boiler came pretty quickly after my check cleared (received a discount for paying by check, which in our case was worth the extra week of processing) and it had everything we needed from mounting to a bottle of corrosion inhibitor.
The Unit itself performs wonderfully: I've got an old 2500 sq ft. house with four zones of fintube freshly installed, zoned by high efficiency pumps on a pump station (all Taco), connected to four smart thermostats. Outdoor reset is all set up and works fine. Unit runs unbelievably quiet, and the on-demand hot water is great.
Advice: if you can sweat pipes and run wire, you can install this unit. The manual is thorough and very helpful. If you decide to hire the job out, get yourself someone that can properly size your system and works extensively on boiler/radiant systems (even if they're a little more expensive).
The boiler came pretty quickly after my check cleared (received a discount for paying by check, which in our case was worth the extra week of processing) and it had everything we needed from mounting to a bottle of corrosion inhibitor.
The Unit itself performs wonderfully: I've got an old 2500 sq ft. house with four zones of fintube freshly installed, zoned by high efficiency pumps on a pump station (all Taco), connected to four smart thermostats. Outdoor reset is all set up and works fine. Unit runs unbelievably quiet, and the on-demand hot water is great.
Advice: if you can sweat pipes and run wire, you can install this unit. The manual is thorough and very helpful. If you decide to hire the job out, get yourself someone that can properly size your system and works extensively on boiler/radiant systems (even if they're a little more expensive).
Alex V. Recommends This
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Expert Response
Thanks for your review, Alex! We're happy you are enjoying your new AquaBalance boiler.

Ken D.
eComfort Product Expert
Rating Breakdown
5/5
5/5
5/5
5/5
Pros:
Quiet, Price, Reliable, High Quality

As advertised
By Robert P.
Waukesha, Wisconsin
Purchased 11/08/2017 |
Review Posted 01/02/2018


I installed this product a little over a month ago and it fired right up. I am not currently using the on demand hot water portion of the heater but have it charged (pressurized) per the manufacturers recommendation and tried it when I originally hooked it up to make sure it was working. On the boiler side it has worked without any issue and the temperature here in WI over the last 30 days has ranged from 30 degrees to -6 Fahrenheit. Unfortunately more on the colder side. The boiler is quiet and has not let me down. The controls are self explanatory and when my first gas bill came it was in line with my previous years consumption. It appears well built so the only thing left now is to see how it holds up over time. It will get a good workout here in WI.
Robert P. Recommends This
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Rating Breakdown
5/5
5/5
5/5
5/5
Pros:
Easy To Use, Price

Awesome Unit
By Gregory P.
Ambridge, Pennsylvania
Purchased 10/11/2017 |
Review Posted 11/27/2017
Replace our 14 year old Quietside Combi Boiler with this unit. Superior in every respect. Lives up to Weil-McLain Reputation. We'll see the longevity in a decade or so
Gregory P. Recommends This
Was this review helpful?
Rating Breakdown
5/5
5/5
5/5
5/5
Pros:
Durable, Quiet, Exceeded Expectations, High Quality
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Weil-McLain AquaBalance™ WMB-155C - 143K BTU - 94.4% AFUE - Combi Gas Boiler - Direct Vent






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