THERMO 2000 ComboMax Ultra 70 Electric Boiler with Built-In Hot Water | 24 kW - 240V
The 24 kW ComboMax ULTRA 70 heats the house and delivers 92 US gal of domestic hot water in 10 minutes, from a single electric appliance.
Model numberCOMBOU70-24
514 316-2973 · sales@airgreen.ca
Quick facts
Enough hot water for the whole family, with home heating included
When the bathroom is never free
In the morning, one shower, then another, the dishwasher running and a bath to fill for the kids in the evening. This is the kind of home where the 24 kW ComboMax ULTRA 70 makes the most sense. For this model, Thermo 2000 publishes 92 US gal of hot water in 10 minutes and 210 US gal in one hour, at 110 °F, from cold water at 40 °F and boiler water at 180 °F.
Those figures come from two things combined: four 6 kW elements, or 81,888 BTU/h at 240 V, and the series’ large 71 US gal tank. That volume of hot water surrounds parallel copper coils. Domestic water flows through them and comes out hot at the tap, without ever being stored, which reduces the risk of Legionella according to the manufacturer.
A boiler that also heats your water
The same tank water supplies your hydronic heating: radiant floor in the basement, radiators upstairs or hydronic baseboards. The T2 UltraSmart controller gives priority to domestic hot water when a tap opens, then returns to heating. It runs the heating pump on thermostat demand and shows the settings on a backlit display. The thermostatic mixing valve comes pre-mounted.
In a Longueuil two-storey or a Laval home where the electric boiler and the water heater are aging together, one appliance replaces both. Thermo 2000 states an expected service life of more than 30 years and minimal maintenance.
What we check before installing
Three points matter. First, the electrical side: the appliance draws 100 A at 240 V, and Thermo 2000 specifies a 125 A breaker and Cu 2 or Al 0 wire. Next, space: 70 1/2 in high, 24 in in diameter and 430 lb, plus the water in the tank. Finally, the heating system, which determines the circulator, the expansion tank and the zones to plan for.
Installation, done by AirGreen
After a free on-site estimate, you receive a written quote covering those three points. On installation day, our technicians remove the old electric boiler and water heater, install the ComboMax, connect it to the heating through its 1 1/4 in NPT connections and to the domestic water through its 3/4 in connections, then make the electrical connection. They fill, purge, set the controller and check the hot water in each bathroom with you.
AirGreen is a family business established in Montreal for more than fifteen years, holding RBQ licence 5645-9605-01 in ventilation, refrigeration and electrical work. On the manufacturer’s side, Thermo 2000 warrants the tank and coils for 15 years in residential use and the electrical and mechanical components for 2 years.
Let’s talk about your home
We install the ComboMax ULTRA in Montreal, Laval, Longueuil, on the North Shore and on the South Shore. Ask for your free estimate and your written quote; financing is available.
For homes that use a lot of hot water
The ComboMax ULTRA 70-24 pairs four 6 kW elements with the series’ large 71 US gal tank. That volume of heating water surrounds the copper coils that make domestic water on demand.
- Families with several bathrooms or a large bathtub
- Homes heated by radiant floors, radiators or hydronic baseboards
- Replacing an electric boiler and a water heater with a single appliance
- Owners who prefer hot water made on demand rather than stored
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- Dedicated 240 V single-phase circuit: the appliance draws 100 A; Thermo 2000 specifies a 125 A breaker and Cu 2 / Al 0 wire.
- At 208 V, output decreases: the manufacturer gives kW x 0.75 and A x 0.867.
- Appliance 70 1/2 in high and 24 in in diameter, weighing 430 lb plus the water in the tank: plan for a suitable floor and access path.
- Maximum working pressure of 30 psi (207 kPa) for heating and 125 psi for domestic water.
- The circulator, expansion tank and heating zones are determined by your system: the written quote details them.
- 30 psi heating relief valve
- 125 psi domestic hot water relief valve
- Drain valve (tank and heat exchanger)
- Temperature and pressure gauge
- Automatic air vent
- 12 psi pressure regulator and check valve (ASSE 1012 / CSA B64-3)
- Thermostatic mixing valve
- Heating elements
- UltraSmart controller
Manufacturer documents
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Frequently asked questions
Is it enough hot water for a large family?
Thermo 2000 publishes 92 US gal in 10 minutes and 210 US gal in one hour, at 110 °F (cold water at 40 °F, boiler water at 180 °F). During the free estimate, we compare those values with your habits: baths, showers, number of bathrooms.
ComboMax ULTRA 70 or 50 at 24 kW?
Both have the same 24 kW output. The 70 has a 71 US gal tank instead of 48 US gal, in an appliance 70 1/2 in high. If space allows, it keeps more heating water around the coils.
Why is no hot water stored?
Domestic water is heated as it flows through copper coils immersed in the heating water. It does not sit in a tank, which reduces the risk of Legionella according to Thermo 2000.
What electrical protection is needed?
A 240 V circuit with a 125 A breaker and Cu 2 or Al 0 wire, per the manufacturer; the appliance draws 100 A. We check the electrical service before confirming the quote.
What warranty does the manufacturer offer?
Thermo 2000 warrants the tank and coils for 15 years in residential use, 10 years in commercial use, and the electrical and mechanical components for 2 years.
A 24 kW ComboMax ULTRA 70, 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.