Water Heating

Toyotomi  OM-128HH

Hydronic Water Heating System

Hydronic water heaters provide a smart home-heating alternative that will lower your energy costs. The OM-128HH model from Toyotomi is a continuous flow water heater that operates at 87% efficiency and saves as much or more than the leading cast iron boilers, at half the size!

OM-128HH Features & Benefits

  • Continuous hot water
  • Compact size and 81 lb. weight allows for one person installation
  • Inlets/outlets on two sides for easy installation
  • Choice of direct vent or chimney vent
  • Cold start capability
  • Flow rate of over 4 gallons per minute with 60°F rise in temperature
  • Approximately 180°F maximum hot water temperature
  • Very quiet and reliable operation
  • Stainless steel heat exchanger
  • Adjustable temperature differential for cycling control
  • Safe: ETL and home and mobile home approved
  • Proven trouble-free performance
  • Limited 10 Year Warranty
  • Learn more at ToyotomiUSA.com
  • Learn more about how hydronic heating works at HydronicHeating.net

Flow Rate/Temperature Rise

6.2 gal/min (40°F rise), 5.0 gal/min (50°F rise)
4.1 gal/min (60°F rise), 3.5 gal/min (70°F rise)
3.1 gal/min (80°F rise)


High Voltage Discharge Spark


87.1% AFUE rating

Fuel Consumption

1.05 gal/hr

Capacity of heat exchanger

5.10 gal


88 lbs

Heating Area

1670 (0°F)
2000 (20°F)

Type of Tank

Exterior Tank

Dimensions (WxHxD)

30 x 27-1/2 x 16-3/4

Temperature Differential Settings

3.6°F, 18°F, 36°F (3 settings by selector switch)

Fuel System

External tank*

Dimensions (WxHxD)

12-5/8 x 27-3/4 x 22-1/2


81 lbs. Empty

Vent Pipe Hole

4-3/4 diameter (for flue pipe installation kit)

Maximum Length of Vent Pipe System

10 ft., 3 bends or less (exhaust pipes for flue pipe installation kit)

Electrical Rating

120 Volts AC, 60 Hz

Fuel Type

ASTM D3699 K1 Kerosene
ASTM D396 No.1 Fuel Oil
ASTM D975 Ultra Low Sulphur Diesel (ULSD)
ASTM D396 No.2 Fuel Oil (Home Heating Oil)

Required Accessories

Flue Pipe Installation Kit or 4 or 5-inch Chimney Adapter Kit

Safety Device

High Limit Thermistor,
Heat Exchanger Bi-metal Switch,
Temperature Fuse, Fusible Link Valve

Exhaust Air Temperature

Less than 500°F

Nozzle Size

0.85 GPH

Spraying Angle


Spray Pattern

Delavan Type XA

Temperature Fuse


Electric Current Fuse

5 A (Main Control)
7 A (Auxiliary Port for Circulation Pump., etc.)

Check State and Local codes/ordinances for permitted use.
Heat and vaporized water are produced by the combustion process of this water heater. This rating does not take into account heat loss due to condensation of water vapor.
*External tank to be purchased from local suppliers.

Comtec Distributing is the nation's leading wholesale distributor of high efficiency home heating and cooling products, specializing in Toyotomi direct vent heating systems and efficient oil stoves from Kuma.

Office Location

1500 Mott Road
Mt. Shasta, CA 96067
Open M-Th 8am-4pm PST

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Contact Us

(800) 795-5925