THERMO 2000 ComboMax Ultra 50 Electric Boiler with Integrated Hot Water | 12 kW - 240V
Thermo 2000’s 12 kW ComboMax Ultra 50: hot-water heating and instantaneous domestic hot water, for 50 A at 240 V.
Model numberCOMBOU50-12
514 316-2973 · sales@airgreen.ca
Quick facts
12 kW of heating and all the home’s hot water, with an electrical load known in advance
A ComboMax Ultra 50 for medium-sized homes
Thermo 2000’s COMBOU50-12 is a hot-water electric boiler that also makes domestic hot water. Two 6 kW elements, on two stages, heat the 48 US gal of water in the tank and deliver 40,944 BTU/h at 240 V to the heating loop: radiators, hot-water baseboards or radiant floors. Parallel copper coils sit in that same water, carrying drinking water that comes out hot without ever being stored.
For hot water, Thermo 2000 publishes 58 US gal in 10 minutes and 116 US gal in one hour, for water delivered at 110 °F, cold water at 40 °F and boiler water at 180 °F. The manufacturer adds that water arrives hot in under 7 seconds and that the absence of stored hot water reduces the risk of Legionella.
The electrical panel first
With 12 kW, the first question is electrical. Thermo 2000 publishes a current of 50 A at 240 V, a 70 A breaker and Cu 6 or Al 4 wire. In a home where the electrical service already feeds a range, a dryer, a water heater and sometimes a charging station, these values are checked before any purchase. That is what we do during the visit: a load calculation, then a clear recommendation.
If your building is supplied at 208 V, the manufacturer states that output is multiplied by 0.75 and current by 0.867. The size remains usable, but the available heat drops; we take that into account in the choice.
How it fits in the basement
The 50 model takes the space of a conventional water heater: 60 in high, 22 in in diameter, 325 lb empty. Heating connections are 1 in male NPT, domestic water connections 3/4 in female NPT. The T2 UltraSmart controller, with a backlit display, gives priority to domestic hot water and runs the heating pump when the thermostat calls; the thermostatic mixing valve is already mounted.
What AirGreen’s installation covers
We work in Montreal, Laval, Longueuil, on the South Shore and the North Shore. It all starts with a free on-site estimate: heating load, hot water needs, electrical load calculation and location. You receive a written quote specifying the unit, the electrical circuit, the loop components and the work.
On installation day, the unit is set in place and connected, by qualified personnel, to the heating loop and to domestic water. The 70 A circuit is connected, the loop filled and purged, then the controller set. We check heating on both stages and water temperature at the taps before leaving.
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’s warranty covers the tank and coils for 15 years in residential use (10 years in commercial use) and electrical and mechanical components for 2 years.
Have your panel and project checked for free: written quote and financing available for the 12 kW ComboMax Ultra 50.
A 12 kW boiler that also makes hot water
The COMBOU50-12 heats a home’s hot-water loop with two 6 kW elements. In the same 48 US gal tank, copper coils heat drinking water as it passes, without storing it.
- Medium-sized homes heated by radiators, hot-water baseboards or radiant floors
- Replacing an electric boiler and a water heater with a single appliance
- Narrow mechanical rooms where only a 22 in diameter unit fits
- Projects where the electrical panel has been checked for another 50 A
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- The panel must accept a 70 A, 240 V single-phase circuit; the unit draws 50 A according to Thermo 2000.
- On a 208 V supply, the manufacturer states that output is multiplied by 0.75 and current by 0.867.
- Footprint: 60 in high and 22 in in diameter; 325 lb empty.
- Maximum working pressure: 30 psi (207 kPa) on the heating side, 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
Explore the range
Electric boilersSee allSame brand
THERMO 2000See all
Frequently asked questions
Can my electrical panel take it?
It needs a 240 V single-phase circuit with a 70 A breaker and Cu 6 or Al 4 wire; the unit draws 50 A according to Thermo 2000. During the free estimate, we check your electrical service’s capacity alongside the appliances already connected.
Our building runs on 208 V. What happens?
The unit works, but at reduced output: according to the manufacturer, kW are multiplied by 0.75 and current by 0.867. We take that into account before recommending this size.
Why two 6 kW elements?
The two elements are split over two stages: the boiler can heat with one element when demand is low, and add the second when it gets colder.
How much hot water does it make?
According to Thermo 2000, 58 US gal in 10 minutes and 116 US gal in one hour, for water at 110 °F, cold water at 40 °F and boiler water at 180 °F.
Who provides the warranty, and for how long?
The warranty is the manufacturer’s, Thermo 2000: 15 years on the tank and coils in residential use (10 years in commercial use) and 2 years on electrical and mechanical components.
The 12 kW ComboMax Ultra 50, planned and 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.