• MAH/MAC 100 - 150

    MAH/MAC 100 - 150

  • MAH/MAC 100 - 150

    MAH/MAC 100 - 150

  • MAH/MAC 125 - 150 Interior

    MAH/MAC 125 - 150 Interior

  • 115/125/150 Manifold

    115/125/150 Manifold

  • MAH/MAC 165-205

    MAH/MAC 165-205

  • MAH/MAC 165-205 Interior

    MAH/MAC 165-205 Interior

  • MAC with Manifold

    MAC with Manifold

  • 165 Manifold

    165 Manifold

  • 205 Manifold

    205 Manifold

  • MAC 115 interior

MAC/MAH High Efficiency Wall Mounted Modulating Condensing Boiler




Boiler with AI [Artificial Intelligence] Control Technology

• Automatically sets up the boiler during initial startup
• Recognizes Natural or LP Gas, no conversion kit required
• Continuously monitors combustion and adjusts gas and air flow to optimize combustion and fuel savings
• User Interface displays temperature status symbols and self diagnostic

95% AFUE, ENERGY STAR® Certified

Primary/Secondary LABOR SAVER™ Manifold Included


*Unit must be registered within 60 days from the date of original installation. All terms of the Trinity Extended Service Agreement apply.





95% AFUE efficiencyENERGY STAR® Certified

 [AI] Control Technology, Auto Commissioning and Continuous Calibration functions optimize combustion and result in lower fuel bills. Control Panel features a backlit digital display that indicates boiler status, temperature, and diagnostics.

6.9:1 Turndown Modulation Ratio in DHW Mode (MAC-115)

7:1 Turndown Modulation Ratio in DHW Mode (MAC-150, MAC-205)

5.6:1 Turndown Modulation Ratio in Heating Mode (MAH-100, MAC-115)

5.7:1 Turndown Modulation Ratio in Heating Mode (MAH-125, MAC-150)

5.5:1 Turndown Modulation Ratio in Heating Mode (MAH-165, MAC-205)

Flow Rate in DHW Mode:

  • 5.0 GPM @ 70° F rise (MAC-205) 
  • 3.5 GPM @ 70° F rise (MAC-150) 
  • 2.5 GPM @ 70° F rise (MAC-115) 

Primary/Secondary LABOR SAVER™ Manifold Included

Heat Exchanger: 316L Stainless Steel Heat Exchanger and Burner. MAC-205, MAC-150 and MAC-115 are also equipped with a Stainless Steel Brazed Plate Heat Exchanger.

Additional Features: Assembled Boiler with Jacket, Induced Draft Fan, High limit sensors, 30psi Relief Valve, Low Water Pressure Switch, Temperature/Pressure Gauge.

Built in load matching Pump contributes to savings in electrical usage


Outdoor Temperature Sensor, Indirect Tank Sensor, Floor Stand Kit

Our AI control technology is programmed to recognize an Indirect Tank. H2O Indirect Hot Water Heaters are available in 30 to 115 gallon capacities and feature 316L stainless steel construction and top connections for an easy installation.


(See Installation, Operation and Maintenance Manual for complete instructions)

Documents / Resources

Current Documents
Archived Documents


User Manual

Installation & Operation Manual

Parts Lists




Boiler Manuals

Engineering Documents / Resources

Parts Manual

Product Testimonials

  • Great product.  Very quiet and reliable.  Good tech support.

    Charles Arnett
    Belpre, OH
  • It's super compact.  The unit is so quiet but my only concern was the water run off, but I muffled that.

    Scott Strother
    Newark, NJ
  • Ease of installation and performance would be the two main features I would share. I also like the quiet operation of the unit. I live in CT, and installation occurred on this winters coldest day. The water inlet temperature is very cold this time of year, and but the on demand DHW comes on pretty quickly and fills a tub super hot.

    Seweryn Borecki
    West Hartford, CT
  • Everything is a optional kit - cumbersome installation.  I have no time for these games.  Condensate kit?  Like it's an option!  Every boiler needs one.  Venting... Really!  I can only use your proprietary venting, what do I do when I'm miles from the whole sale house and someone misses a fitting, oh wait does not matter they don't even stock it.  Now my customer has no heat and its 4 below.  I can not install a product that let's me and my former customer down.  You missed the mark 100% on this one!

    Mike Hoheisel
    Royalton, MN
  • Very clean, doesn't take up much room and works great!

    Nicole Talaia
    Chicopee, MA
  • This boiler installed very quickly and easy.

    Chris Ghosio
    Medford, NY
  • I have recommended this product and another install is in the works.

    Gibney Builders
    Altoona, PA
  • I would recommend it and have.  It is so nice to have on demand hot water and there is no noise.

    Patricia Gardner
    Essex, NY
  • Great boiler very efficient and definitely quiet. Easy to install.

    Ty Kovalewski
    Lafayette, NY
  • The overall dimenseions, efficiency, and ease of use is great. After speaking to many installers/ HVAC technicians, Utica was the most frequently suggested brand to purchase. Low maintenance, quality of construction, and high quality components were the main reasons for the recommendations. 

    Jason Matthews
    Wilbraham, MA
  • Yes I would recommend this product because it is small, compact, quiet and easy to install.

    Charlie Cashin
    Boxford, MA
  • Yes I would recomment this product.  Unit is very quiet, east to install, and a great value compared to other brands.

    Red Riehle
    Old Forge, NY
  • I would recomment this product.  The product is very efficient and works great.  

    I would strongly recommend this product to anyone in need of replacing existing boiler/water heater or just upgrading for efficiency purposes.

    Jorge Morales
    Lawrence, MA
  • Works well.  

    On the Mac 150 if they had the hot and cold inlets off set from the boiler inlet and out let it would ease the install, now they are all inline.

    Gary Adams
    Lafayette, NY
  • Yes I would recomment this product to a friend.  Dependable, easy to install, and helpful tech support.  

    Edward Hosmer
    Belchertown, MA
  • Saving money and energy with your product.

    Spring brook fuel and ice should NOT be installing your product no license and don’t know what they are doing. Without your rep my unit would not be working.

    New Britain, CT
  • This was an easy installation and is a good boiler for larger homes.

    I had a hard time with the venting of this boiler. The supply house didn't have a good knowledge of this product. I was told I could vent it with 2" pipe. After talking to the factory service and engineering department I was still unsure of how to vent it. Help finaly came when I talked to Howard Dyson and Gary Alex. I ended up venting the boiler with 2" cpvc on the exhaust side and pvc on the intake.

    East Haddam, CT
  • I highly recommend Utica Boilers. Built in USA. Rep for company is very helpful

    New Britain. CT
  • The 40 year old boiler we had never gave us a problem but replaced to be more efficient

    Salisbury, MA
  • Easy installation and user friendly

    East Longmeadow, MA
  • Looks good, runs good. Having some issues with the hot water not mixing properly all the time. Install company not sure what is causing it.

    Becket, MA
  • Nice compact unit. Longer horizontal combi venting runs are difficult.

    Quarryville, PA
  • Easy install customer support was fast and easy

    Waltham, MA
  • Very efficient and fairly easy to install. Had no issues upon startup

    Lincoln Park, NJ
  • Every contractor I talked to said this is the best boiler they have installed!

    Verona, NY
  • I'll recommend it to my customers. It's made nice. Easy to work on it.

    Zigzag Industrial
    New Milford, NJ
  • Yes, great space saver and love the unlimited hot water.

    Middleville, MI