THERMO 2000 ComboMax Ultra 70 Electric Boiler with Integrated Hot Water | 7.5 kW - 240V
7.5 kW two-stage hot-water heating and instantaneous domestic hot water: Thermo 2000’s ComboMax Ultra 70, with its 71 US gal tank.
Model numberCOMBOU70-7,5
514 316-2973 · sales@airgreen.ca
Quick facts
113 US gal of hot water in one hour and 7.5 kW of heating, in a single appliance
Two bathrooms, one heat source
When a home has two bathrooms, hot water goes fast: a shower upstairs, a bath on the ground floor, the washer at the same time. Thermo 2000’s 7.5 kW ComboMax Ultra 70 was designed for that pace. According to the manufacturer, it delivers 76 US gal of hot water in 10 minutes and 113 US gal in one hour, for water at 110 °F, cold water at 40 °F and boiler water at 180 °F. It also heats the whole house through the hot-water loop: radiators, hydronic baseboards or radiant floors.
What happens inside the tank
The tank holds 71 US gal of heating water. Two elements, 3 kW and 4.5 kW, heat it on two stages, up to 25,590 BTU/h at 240 V. Parallel copper coils sit in that body of water: drinking water flows through them and heats up on the way. So no domestic hot water is stored. Thermo 2000 states that it arrives hot in under 7 seconds and that this design reduces the risk of Legionella.
The T2 UltraSmart controller arbitrates between the two uses. It gives priority to domestic hot water, manages its temperature and runs the heating pump when the thermostat calls. At the outlet, the pre-mounted thermostatic mixing valve delivers a steady temperature to the taps.
Before choosing: height, weight and panel
The 70 model is 70 1/2 in high and 24 in in diameter, and weighs 430 lb empty. In a semi-detached house in Laval or a two-storey home on the North Shore, the basement stairs and the clearance under the beams often decide the location; we check them on site. Electrically, a 240 V single-phase circuit with a 40 A breaker and Cu 8 or Al 6 wire is needed. At 208 V, output is multiplied by 0.75 according to the manufacturer. Connections are 1 1/4 in male NPT for heating and 3/4 in female NPT for domestic water.
How we install
We start with a free estimate at your home, in Montreal, Longueuil, on the South Shore or elsewhere in Greater Montreal. We talk about your hot water habits, measure the space, check the panel and the heating system. The written quote that follows specifies the unit, the loop components and the work.
On installation, the unit is set in place, then connected by qualified personnel to the heating loop and to domestic water. The accessories supplied by Thermo 2000 (pressure regulator with check valve, automatic air vent, temperature and pressure gauge, 30 psi and 125 psi relief valves) are largely already mounted. After the electrical connection, we fill and purge the loop, set the controller and test 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 and written quote: financing is available for the 7.5 kW ComboMax Ultra 70.
Hot water for two bathrooms and heat for the whole house
The COMBOU70-7,5 heats the home’s hot-water loop with two elements (3 kW and 4.5 kW) and makes domestic hot water on demand, in copper coils immersed in 71 US gal of heating water.
- Homes with two or more bathrooms
- Semi-detached and two-storey houses heated by radiators or radiant floors
- Replacing an electric boiler and a water heater with a single appliance
- Households that 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
- 70 1/2 in high, 24 in in diameter and 430 lb empty: check the clearance and the access path to the mechanical room.
- 40 A breaker and Cu 8 / Al 6 wire at 240 V single phase, according to Thermo 2000. At 208 V, output is multiplied by 0.75.
- 1 1/4 in male NPT heating connections; 3/4 in female NPT domestic water connections.
- Maximum working pressure of 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 can be drawn in a row?
Thermo 2000 publishes 76 US gal in 10 minutes and 113 US gal in one hour, for water delivered at 110 °F, with cold water at 40 °F and boiler water at 180 °F. During the visit, we compare these values with your habits.
How does it differ from the 7.5 kW ComboMax Ultra 50?
Both have the same heating output and the same elements. The COMBOU70-7,5 has a larger tank that delivers more hot water, but it is taller and heavier than the COMBOU50-7,5.
What is the thermostatic mixing valve for?
It blends the hot water made by the coils with cold water to deliver a steady temperature at the taps. It is supplied and pre-mounted by Thermo 2000.
Does it need much maintenance?
Thermo 2000 announces minimal maintenance and an expected service life of more than 30 years. We walk you through the basic checks at start-up.
What electrical circuit is needed?
A 240 V single-phase circuit, with a 40 A breaker and Cu 8 or Al 6 wire, according to the manufacturer.
A 7.5 kW ComboMax Ultra 70 for a two-bathroom home
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.