THERMO 2000 ComboMax Ultra 50 Electric Boiler with Built-In Hot Water | 24 kW - 240V
The 24 kW ComboMax ULTRA 50 fits an electric boiler and an instantaneous water heater into the compact size of the series: 60 in high, 22 in in diameter.
Model numberCOMBOU50-24
514 316-2973 · sales@airgreen.ca
Quick facts
24 kW of heat and hot water for the whole house, in an appliance 60 in high
Who the ComboMax ULTRA 50-24 is for
Some mechanical rooms leave little choice: a closet in the basement, a corner under the stairs, a low ceiling. The 24 kW ComboMax ULTRA 50 answers those cases. Thermo 2000 combines an electric boiler and an instantaneous water heater in a single appliance 60 in high and 22 in in diameter, built around a 48 US gal tank. It is the compact size of the series, and among the ComboMax ULTRA 50 models we offer, 24 kW is the highest.
Four 6 kW elements, spread over four stages, heat the water in the tank, which then circulates through the radiant floor, radiators or hydronic baseboards. The appliance delivers 81,888 BTU/h at 240 V. Domestic water, for its part, flows through copper coils immersed in the heating water and comes out hot, without ever being stored.
More hot water without an extra tank
For this specific model, Thermo 2000 publishes 69 US gal of hot water in 10 minutes and 187 US gal in one hour, at 110 °F, from cold water at 40 °F and boiler water at 180 °F. The manufacturer states that the ULTRA 50-24 gives on average 60% more hot water in one hour than a conventional electric water heater. For a family in Laval or on the North Shore sharing one or two bathrooms, that means back-to-back showers in the morning, with a single appliance to maintain.
The thermostatic mixing valve is pre-mounted, as are the pressure regulator with check valve, the air vent, the temperature and pressure gauge and the domestic water relief valve. The T2 UltraSmart controller gives priority to hot water and runs the heating pump when the thermostat calls for it.
Electrical capacity, the first thing to confirm
At 24 kW, the appliance draws 100 A at 240 V. Thermo 2000 specifies a 125 A breaker and Cu 2 or Al 0 wire. In a Montreal home that still has a small electrical service, it is the first thing we check. If the building is supplied at 208 V, output drops according to the factor published by the manufacturer (kW x 0.75).
What installation by AirGreen includes
We start with a free on-site estimate: heating system, hot water needs, electrical panel and access to the mechanical room. The written quote that follows specifies the size, the circulator, the expansion tank and the heating zones. Our technicians then install the ComboMax, connect it to the heating system through its 1 in NPT connections and to the domestic water through its 3/4 in connections, make the electrical connection, fill and purge the system, then set the controller with you.
A family business established in Montreal for more than fifteen years, AirGreen holds RBQ licence 5645-9605-01 in ventilation, refrigeration and electrical work. Thermo 2000 warrants the tank and coils for 15 years in residential use, and the electrical and mechanical components for 2 years.
Ask for your estimate
AirGreen installs the ComboMax ULTRA in Montreal, Laval, Longueuil, on the North Shore and on the South Shore. The on-site estimate is free, the quote is in writing, and financing is available to carry out the project at your own pace.
Plenty of heat and hot water in a small footprint
The ComboMax ULTRA 50-24 carries four 6 kW elements in a 48 US gal tank, the smallest in the series. The water in that tank supplies the hydronic heating and heats the domestic water in copper coils, at the moment it is needed.
- Townhouses and semi-detached homes with a narrow mechanical room
- Replacing an electric boiler and a water heater with a single compact appliance
- Heating by radiant floor, radiators or hydronic baseboards
- Households that want more hot water without adding a tank
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, the manufacturer says to multiply kW by 0.75 and amps by 0.867.
- Space needed: 60 in high and 22 in in diameter. The appliance weighs 325 lb, plus the water in the tank once filled.
- Maximum working pressure of 30 psi (207 kPa) on the heating side and 125 psi on the domestic water side.
- The circulator, expansion tank and zoning depend on the heating system: they are listed in our written quote.
- 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
Why choose the 50 version over the 70?
The 50 version has a 48 US gal tank in an appliance 60 in high and 22 in in diameter. The ComboMax ULTRA 70 of the same output has a 71 US gal tank and takes up more room. The 50 suits a mechanical room with limited height or access.
How much hot water does it deliver?
Thermo 2000 publishes 69 US gal in 10 min and 187 US gal in 1 h, for water at 110 °F from cold water at 40 °F and boiler water at 180 °F. The manufacturer adds that it gives on average 60% more hot water in one hour than a conventional electric water heater.
Can my electrical panel handle it?
The appliance draws 100 A at 240 V and Thermo 2000 specifies a 125 A breaker. Depending on the home’s electrical service, an upgrade may be needed: we check it during the free estimate and state it in the quote.
Is the hot water stored in the tank?
No. The tank holds the heating water. Domestic water flows through copper coils immersed in that water and is heated on demand, which reduces the risk of Legionella according to the manufacturer.
How long does a ComboMax last?
Thermo 2000 states an expected service life of more than 30 years with minimal maintenance. It 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 50, 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.