THERMO 2000 ComboMax Ultra 70 Electric Boiler with Integrated Hot Water | 18 kW - 240V
Thermo 2000’s 18 kW ComboMax Ultra 70 pairs 61,416 BTU/h of heating with 175 US gal of hot water in one hour.
Model numberCOMBOU70-18
514 316-2973 · sales@airgreen.ca
Quick facts
175 US gal of hot water in one hour and 18 kW of heating, for homes that ask a lot
When heating and hot water both draw at once
A January morning in a large home: the radiant floor is calling for all its heat, and several people shower one after another. That is the situation where Thermo 2000’s 18 kW ComboMax Ultra 70 makes the most sense. Its T2 UltraSmart controller gives priority to domestic hot water, then returns to heating when the thermostat calls. According to the manufacturer, it delivers 87 US gal of hot water in 10 minutes and 175 US gal in one hour, for water at 110 °F, cold water at 40 °F and boiler water at 180 °F.
What is inside the unit
Four identical 4.5 kW elements, split over four stages, heat the 71 US gal of water in the tank up to 61,416 BTU/h at 240 V. That water circulates in the heating loop to the radiators, hot-water baseboards or radiant floor. Parallel copper coils sit in the tank: drinking water flows through them and heats up on the way, without being stored. Thermo 2000 states that it arrives hot in under 7 seconds and that the absence of storage reduces the risk of Legionella. At the outlet, the pre-mounted thermostatic mixing valve tempers the water sent to the taps.
The conditions to meet
The unit draws 75 A at 240 V. Thermo 2000 specifies a 100 A breaker and Cu 4 or Al 2 wire, which assumes an electrical service with capacity to spare. At 208 V, output is multiplied by 0.75 and current by 0.867. Physically, the unit is 70 1/2 in high and 24 in in diameter and weighs 430 lb empty: the basement stairs, the doors and the clearance under the beams matter as much as the floor space. Connections are 1 1/4 in male NPT for heating and 3/4 in female NPT for domestic water.
Our installation, from visit to start-up
For a home in Montreal, Laval, Longueuil, on the South Shore or the North Shore, it all starts with a free estimate. We calculate the heating load, check the electrical service, talk about your hot water use and note the access path. You receive a written quote detailing the unit, the 100 A circuit, the loop components and the work.
On the day, the unit is set in place and connected, by qualified personnel, to the heating loop and to domestic water. The accessories supplied by Thermo 2000 (12 psi pressure regulator, check valve, automatic air vent, temperature and pressure gauge, 30 and 125 psi relief valves) are installed or already mounted. After the electrical connection, we fill and purge the loop, set the controller and test heating on all four stages, then hot water at several taps.
AirGreen is a family business established in Montreal for more than fifteen years, holding RBQ licence 5645-9605-01 (ventilation, refrigeration and electrical). Thermo 2000 covers the tank and coils for 15 years in residential use (10 years in commercial use) and electrical and mechanical components for 2 years.
Ask for your free estimate: written quote and financing available for the 18 kW ComboMax Ultra 70.
For homes where heating and hot water both draw hard at once
The COMBOU70-18 combines four 4.5 kW elements with the large 71 US gal tank. The copper coils immersed in that heating water make domestic hot water as it flows, and the controller gives it priority.
- Large family homes with several bathrooms
- Homes heated by radiant floors or radiators whose load justifies 18 kW
- Replacing a high-output electric boiler and a large water heater
- Owners who would rather not store hot water
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- The unit draws 75 A at 240 V; 100 A breaker and Cu 4 / Al 2 wire according to Thermo 2000. At 208 V, output is multiplied by 0.75.
- 70 1/2 in high, 24 in in diameter and 430 lb empty: check the stairs and doors leading to the mechanical room.
- 1 1/4 in male NPT heating connections; 3/4 in female NPT domestic water connections.
- Maximum working pressure: 30 psi (207 kPa) on the heating side and 125 psi on the domestic water side.
- 30 psi heating relief valve
- 125 psi domestic hot water relief valve
- Tank and heat exchanger drain valves
- Temperature and pressure gauge
- Automatic air vent
- 12 psi pressure regulator
- Check valve (ASSE 1012 / CSA B64-3)
- Thermostatic mixing valve
- Heating elements and T2 UltraSmart controller
Manufacturer documents
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Frequently asked questions
How much hot water does it make?
Thermo 2000 publishes 87 US gal in 10 minutes and 175 US gal in one hour for the COMBOU70-18, with water delivered at 110 °F, cold water at 40 °F and boiler water at 180 °F.
Is it safer than a tank water heater?
On the question of Legionella, Thermo 2000 states that the absence of stored hot water reduces the risk: drinking water is heated as it passes through the copper coils, then tempered by the supplied thermostatic mixing valve.
Will the unit fit down a basement staircase?
It is 70 1/2 in high and 24 in in diameter and weighs 430 lb empty. We check the stairs, doors and location during the free estimate.
How do the four elements work?
The four 4.5 kW elements are split over four stages: output is added in steps according to demand, up to 18 kW.
Does the warranty cover the coils?
Yes. Thermo 2000 covers the tank and coils for 15 years in residential use (10 years in commercial use); electrical and mechanical components are covered for 2 years.
An 18 kW ComboMax Ultra 70 for heavy demand, installed by AirGreen
Tell us about your project: we check the sizing, confirm availability and send you a quote. Or let our technicians install it for you.
Specifications from the manufacturer’s documentation, checked on October 19, 2026.