Greenstar 151


Energy-saving & environmental features 

Aluminum-Silicon heat exchanger delivers high efficiency - 96.8% with low temperature applications (94.3% AFUE)

Low NOx emissions ahead of 2012 SCAQMD regulations

Simple, intelligent control options optimize efficiency and fuel consumption

Low electrical consumption when the boiler is in standby mode

Electronic ignition

Anti-cycle and modulation control


End user comfort & convenience features


Limited lifetime heat exchanger and 5-year parts & labor warranty

All models available as NG or LP

Special insulation ensures ultra-quiet operation

Compact dimensions and built-in frost protection offer flexibility for location of installation

ECO mode for energy saving fuel consumption

Exclusive safety feature - keypad safety lock prevents unwanted tampering with the heating controls




 Al-Si heat exchanger 

Each unit features an ASME approved Al-Si heat exchanger constructed of advanced Magnesium-Aluminum-Silicon alloy - offering increased flexibility versus traditional stainless steel. They are equipped with highly durable heating blocks that are corrosion resistant and designed to optimize clean burning combustion over an extra large surface area, which requires minimal servicing and reliance on spare parts during the boiler’s lifetime.


Full modulating fan assembly 

A full modulating fan automatically increases or decreases its speed according to the amount of gas coming into the boiler depending on the heat demand. This process, called modulation, prevents the boiler from either having too little or too much air in the unit for optimal combustion - ensuring high efficiency.





Greenstar 151Performance Specifications
Fuel NG/LP
Input Maximum (MBH) 151.6
Input Minimum (MBH) 36
DOE Heating Capacity (MBH) 134.4
Net I=B=R (MBH) 117
AFUE 94.3%
Low Temp Application Efficiencies 96.8%
DHW Flow Max (ΔT at 72°F) -
Water Volume 0.952 Gal. (3.5 L)
Technical Data Technical Data
Weight (without packaging) 103.6 Lbs. (47 kg)
Dimensions (w x h x d) 17.4" x 33.5" x 13.9"
Minimum Recommeded Pipe Size 1"
Supply Tappings 1"
Return Tappings 1"
Domestic Hot Water Supply -
Domestic Cold Water Supply -
Gas Connection Size ¾"
Vent Size 2"-3"
Vent Material PVC/CPVC
Combustion Air Size 2" - 3"
High Altitude Capability De-Rated
Gas Pressure Minimum w.c. NG 3.5" - LP 8"
Included Package Contents Included Package Contents
AI-Si Heat Exchanger
3 Speed Grundfos Integrated Pump -
Integrated Expansion Vessel
FW200 Weather Compensation Control
Heatronic III - Control PCB
Hydronics Manifold Bracket with NPT Connection
Twin Pipe Flue Adapter
Tank Sensor
System Supply Sensor
NG / LP Conversion Kit
Condensate Trap Drain Hose




Limited Warranty

  • 5 year parts & labor
  • Lifetime heat exchanger