The T-H1 model, Takagi's "Condensing" unit, is one of the most enegy efficient tankless units (up to 95% in thermal efficiency) in the Tankless industry.  The T-H1 was designed for residential and commercial use and offers direct vent capability and much more.
 

Natural Gas Input 
Min. 15,000 Btu 
 Max. 199,000 Btu 

LPG Input 
Min. 18,000 Btu 
 Max. 190,000 Btu 

Gas Connection 
3/4" NPT 
  

Water Connection 
3/4" NPT 
  

Condensate Water Drain 
1/2" NPT 
  

Natural Gas Pressure Inlet 
Min. 5.0" WC 
 Max. 10.5"WC 

LP Gas Pressure Inlet 
Min. 11"WC 
 Max. 14"WC 

Weight 
90 lbs 
  

Dimensions 
29.5" x 18.9" x 11.8" 
  

Ignition 
Electronic Ignition 
  

Electrical Supply 
AC 120V (60 Hz) 
  

Water Pressure 
Min. 15 psi 
 Max. 150 psi 

Natural Manifold Pressure 
2.6" W.C. 
  

LP Manifold Pressure 
2.8" W.C.