THERMO 2000 AltSource 50 Thermal Mass Electric Boiler | 15 kW - 240V
The 15 kW AltSource 50 spreads its output across four elements and four stages, with 48 US gal of water in reserve, as the backup of a renewable heating system.
Model numberALTSOURCE50-15
514 316-2973 · sales@airgreen.ca
Quick facts
Four stages of output for 15 kW of backup: the AltSource 50 that meters its heat
A graduated backup, in four steps
The higher a boiler’s output, the more useful it becomes to meter it. Thermo 2000’s AltSource 50-15 splits its 15 kW, or 51,180 BTU/h at 240 V, between four elements: two of 3 kW and two of 4.5 kW, controlled in four stages. The T2 UltraSmart controller can therefore add heat in steps, based on the outdoor temperature measured by the supplied sensor.
Like the whole series, it is a thermal mass electric boiler, which the manufacturer presents as the only high water volume electric boiler on the market. Its tank holds 48 US gal of water, and its role is to be the backup source of a renewable-energy heating system: air-to-water heat pump, geothermal or solar.
Where it fits
Picture a large house on the South Shore with radiant floor heating on the ground floor and in the basement, and a geothermal system as the main source. In the fall, geothermal does the job on its own; in deep cold, the AltSource 50-15 adds one, two, three or four stages as needed. In mild weather, the controller shuts heating off, and a Boost mode is also available.
The 48 US gal version has the advantage of compactness: 22 in in diameter, 25 1/2 in deep with the door and 56 7/16 in high, for 280 lb before filling. It connects in 1 in male NPT and operates at a maximum pressure of 30 psi.
Electrical: what Thermo 2000 lists
The manufacturer lists an 80 A breaker and Cu 6 / Al 4 wire gauge at 240 V single phase. In a building with a 208 V supply, output becomes 11.2 kW at 54.3 A. At this output level, we always check the electrical service’s capacity before confirming the project.
Installation, from start to finish
After a free on-site estimate, you receive a written quote that specifies the boiler, circulator, expansion tank and electrical work. For the tank, Thermo 2000 recommends a #30 with a radiant floor or baseboards, and a #60 with cast-iron radiators. Our technicians then set the unit in place, connect it to the loop and the circuit, mount the supplied outdoor sensor, relief valve and air vent, then fill, purge and set up the system with you.
Thermo 2000 covers the tank for 15 years in residential use and the electrical and mechanical components for 2 years. 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.
Let’s plan your project
In Montreal, Laval, Longueuil, on the North Shore or on the South Shore, ask for your free estimate. You receive a clear written quote, and financing is available.
A 15 kW backup that meters its heat
With four elements controlled in four stages, the AltSource 50-15 adds its heat in steps, as the backup of an air-to-water heat pump, a geothermal system or solar collectors.
- Large house with radiant floor heating on two storeys
- Backup for a geothermal system whose demand varies widely with the season
- Air-to-water heat pump feeding baseboards and a radiant floor
- Mechanical room with limited floor space
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- Thermo 2000 lists an 80 A breaker and Cu 6 / Al 4 wire gauge at 240 V single phase.
- At 208 V, output drops to 11.2 kW (54.3 A).
- The circulator and expansion tank are not on the list of supplied parts; recommended tank #30 for baseboards or a radiant floor, #60 for cast-iron radiators.
- Height of 56 7/16 in; weight of 280 lb, plus the water in the tank once filled.
- 1 in male NPT fittings and maximum working pressure of 30 psi (207 kPa).
- 30 psi (207 kPa) relief valve
- Drain valve
- Temperature and pressure gauge
- Automatic air vent
- Heating elements
- UltraSmart controller
- Outdoor sensor
Manufacturer documents
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Frequently asked questions
Why four stages?
The 15 kW is split between four elements, two of 3 kW and two of 4.5 kW, controlled in four stages. The T2 UltraSmart controller can therefore add output in steps rather than all at once.
What breaker is needed?
Thermo 2000 lists an 80 A breaker and Cu 6 or Al 4 wire gauge at 240 V. We check your electrical service’s capacity during the estimate.
What happens at 208 V?
Output becomes 11.2 kW and current 54.3 A, according to the manufacturer. We take this into account when choosing the size.
AltSource 50 or AltSource 70 at 15 kW?
The output is the same; the AltSource 70 holds 71 US gal of water instead of 48 US gal, in a wider and heavier unit. The AltSource 50 suits rooms where space is tight.
Up to what temperature does it heat water?
The operating range runs from 50 °F to 190 °F (10 °C to 88 °C), which covers radiant floors, baseboards and radiators.
A 15 kW AltSource 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.