The OM-122DW SEMI-ON-DEMAND Water Heater
No costly storage of hot water until it is needed!
Domestic hot water capacity 148 MBH, giving an 80°F T @ 3.0 usgpm water flow rate.
–In stock for direct shipment–
Vent kits (direct vent, or chimney adapter) are priced separately on the accessories page.
Save Money!
Save Energy!
Only Heat Water When You Need It!

- Economical: Some consumers have reduced hot water heating costs by up to 50%!
- Heats the water you need, when you need it…up to 240 gallons per hour!
- Consistent water temperature.
- Stainless steel heat exchanger!
- 88% efficient!
- Proven trouble-free performance
- Safe: ETL and CETL home and mobile home approved
- Direct vent or chimney vent!
- Small, compact size
- Limited 10 YEAR WARRANTY
INSTALLATION NOTES: (Please refer to installation instructions below for complete details)
- Direct vent installation is the recommended method, but a chimney adapter is available. A Flue extension adapter is available for walls thicker than the standard flue pipe (10″). See the accessories page for venting extension kits. Maximum vent length is 10 feet with 3 elbows.
- OIL-MISER unit will also operate with #2 home heating fuel. Better grade fuel oils are recommended for cleaner burning, and must always be used when the oil tank is located outside.
- Gravity feed of oil from tank to boiler. Optional fuel lifter pump is available on the accessories page.
OM-122DW WATER HEATER – WEIGHT AND SHIPPING SIZES:
Width | Depth | Height | Weight | Price |
14″ | 24″ | 28″ | 90 lbs | |
36cm | 61cm | 72cm | 41 kg |
Download OM-122DW Information:
DOWNLOAD: SERVICE MANUAL for OM-122DW and OM-128HH
DOWNLOAD: Operation and Maintenance Instructions
TÉLÉCHARGER: Manuel d’installation
TÉLÉCHARGER: Instructions d’utilisation et d’entretien
Photos:
Videos: remark: the OM-148 was recently replaced by model OM-122DW. These are comparable.
OM-148 Water Heater | Toyotomi* Water Heater Introduction | Water Heater Possible Issues |
OM-122DW TOYOTOMI* SEMI-ON-DEMAND WATER HEATER Specs:
Model | OM-122DW |
Type | Combustion Type – Oil Pressure Vapor Flue Pipe – Forced Flue / Chimney Vent Heating System – Semi-On-Demand Purpose – Domestic Hot Water Heater |
Ignition | High Voltage Discharge Spark |
Fuel Type: | ASTM D396 No.2 FUEL OIL (HOME HEATING OIL) ASTM D396 NO.1 LOW SULFUR FUEL OIL ASTM D975 ULTRA LOW SULFUR HEATING OIL/ DIESEL ASTM D3699 K1 KEROSENE |
Efficiency | 88%(1) |
Hot Water Input | 148,000 BTU/h |
Fuel Consumption | 1.05 gal./h |
Max. Hot Water Temperature | 155°F (approximately) |
Water Flow Rate/ Temperature Rise: |
6.1 gal./min. (40°F rise) 4.8 gal./min. (50°F rise) 4.0 gal./min. (60°F rise) 3.5 gal./min. (70°F rise) 3.0 gal./min. (80°F rise) |
Capacity of Heat Exchanger | 5.10 gal. |
Area of Heat Transmission | 9.7 ft.2 |
Fuel System | External Tank(1) Gravity Fed |
Dimensions (W x H x D) | 12-5/8″ x 27-3/4″ x 22-1/2″ |
Weight | 79 lbs. Empty |
Vent Pipe Hole | 4-3/4″ diameter |
Max. Length of Vent Pipe | 10 ft., 3 bends or les |
Electric Rating | 120 Volts AC, 60 Hz Ignition – 120W Burning – 98W |
Required Accessories | Fuel filter, Flue pipe installation kit (Part #20476440) or Chimney installation adapter kit (Part#20476430 – 5 inch kit or #20476415 – 4 inch kit) |
Exhaust Air Temperature | Less than 500°F |
Nozzle | Quantity of Vapor – 0.85 GPH Delavan type XA Spraying Angle – 60° Spray pattern: Delavan Type XA |
Temperature Fuse | 282° F |
Electric Current Fuse | 5A |
(1) 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.
(2) External tank to be purchased from local suppliers.