THERMO 2000 ComboMax Ultra 50 Electric Boiler with Integrated Hot Water | 20 kW - 240V
Thermo 2000’s 20 kW ComboMax Ultra 50: 68,240 BTU/h of hot-water heating and instantaneous domestic hot water, in a 48 US gal tank.
Model numberCOMBOU50-20
514 316-2973 · sales@airgreen.ca
Quick facts
20 kW of heating and instantaneous hot water, in the compact 48 US gal tank
Big heating in a small mechanical room
Row houses and townhouses often have a closet-sized mechanical room, while their radiant floor covers every level. Thermo 2000’s 20 kW ComboMax Ultra 50 addresses that situation: 68,240 BTU/h at 240 V in a unit 60 in high and 22 in in diameter, weighing 325 lb empty. According to the manufacturer, that is the space of a conventional water heater, and the unit does replace the water heater, since it also makes domestic hot water.
Four 5 kW elements and a water heater with no reserve
Output is split between four 5 kW elements on four stages, which are added according to demand. The 48 US gal tank holds the heating water; parallel copper coils are immersed in it, and drinking water heats up as it passes through them. No hot water is stored. Thermo 2000 publishes 66 US gal of hot water in 10 minutes and 163 US gal in one hour, for water delivered at 110 °F, cold water at 40 °F and boiler water at 180 °F, and specifies that water arrives hot in under 7 seconds.
The T2 UltraSmart controller, with a backlit display, gives priority to domestic hot water, manages its temperature and runs the heating pump when the thermostat calls. Several accessories arrive pre-mounted: pressure regulator with check valve, thermostatic mixing valve, air vent, temperature and pressure gauge and hot water relief valve.
The electrical circuit, the first thing to check
Thermo 2000 specifies a 110 A breaker and Cu 3 or Al 2 wire on a 240 V single-phase circuit. That is a large circuit for a home: before recommending this size, we do a load calculation of the electrical service with all the appliances already connected. In a building supplied at 208 V, output is multiplied by 0.75 and current by 0.867, according to the manufacturer.
What AirGreen’s installation covers
Our work starts before the order, with a free estimate in Montreal, Laval, Longueuil, on the South Shore or the North Shore. We measure the mechanical room, calculate the heating load, check the electrical service and discuss your hot water needs. The written quote describes the unit, the 110 A circuit, the loop components and the work.
On installation, the unit is set in place and connected, by qualified personnel, to the heating loop (1 in male NPT) and to domestic water (3/4 in female NPT). After the electrical connection, the loop is filled and purged, the controller set, and we check all four stages and water temperature at the 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.
Have your project assessed for free: written quote and financing available for the 20 kW ComboMax Ultra 50.
Plenty of heating where space is short
The COMBOU50-20 combines four 5 kW elements with the series’ compact 48 US gal tank. Drinking water flows through copper coils immersed in the heating water and comes out hot, without being stored.
- Row houses and townhouses heated by radiant floors
- Homes whose mechanical room only leaves space for a 22 in diameter unit
- Replacing a high-output electric boiler and a water heater
- Projects where the electrical service can take a 110 A circuit
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- 240 V single-phase circuit with a 110 A breaker and Cu 3 / Al 2 wire, according to the manufacturer: the electrical service must have that capacity available.
- At 208 V, output is multiplied by 0.75 and current by 0.867, according to Thermo 2000.
- 1 in male NPT heating connections; 3/4 in female NPT domestic water connections.
- 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
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Frequently asked questions
Does it replace the water heater too?
Yes, if its output covers your needs: Thermo 2000 publishes 66 US gal of hot water in 10 minutes and 163 US gal in one hour (water at 110 °F, cold water at 40 °F, boiler water at 180 °F). We compare these values with your use during the visit.
What electrical circuit is needed?
A 240 V single-phase circuit with a 110 A breaker and Cu 3 or Al 2 wire, according to the manufacturer. It is a large circuit: we check your electrical service’s capacity before recommending this size.
Our building runs on 208 V. Is that possible?
Yes, but Thermo 2000 states that at 208 V output is multiplied by 0.75 and current by 0.867. We check that the available heat is enough.
How does it differ from the 20 kW ComboMax Ultra 70?
Heating is the same as the COMBOU70-20. The COMBOU50-20 has a smaller tank that delivers less hot water, but it is shorter, narrower and lighter.
Which accessories arrive pre-mounted?
According to Thermo 2000, the pressure regulator with check valve, the hot water mixing valve, the air vent, the temperature and pressure gauge and the hot water relief valve are pre-mounted. The 30 psi heating relief valve and the drain valves are also supplied.
The 20 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.