THERMO 2000 AltSource 50 Thermal Mass Electric Boiler | 12 kW - 240V
The 12 kW AltSource 50 pairs two 6 kW elements with a 48 US gal tank: a 40,944 BTU/h electric backup for a renewable heating system.
Model numberALTSOURCE50-12
514 316-2973 · sales@airgreen.ca
Quick facts
12 kW, two 6 kW elements and 48 US gal of water: the AltSource 50 for homes moving to renewables
What the AltSource 50-12 is
Thermo 2000 designed the AltSource for a very specific role: to serve as the backup source of a renewable-energy heating system, whether an air-to-water heat pump, geothermal or solar. It is a thermal mass electric boiler, which the manufacturer presents as the only high water volume electric boiler on the market. The 50-12 model combines a 48 US gal tank with 12 kW at 240 V, or 40,944 BTU/h, split between two 6 kW elements over two stages.
A Laval home changing its boiler
Take a house in Laval heated for years by an electric boiler and hot-water baseboards. The owners install an air-to-water heat pump, which now handles most of the heating, and replace the old boiler with an AltSource 50-12. The loop stays in place; the AltSource connects to it in 1 in male NPT and supplies backup heat when the main source falls short.
The T2 UltraSmart controller and the outdoor sensor are supplied. They modulate output and water temperature on the outdoor temperature, shut heating off in warm weather and offer a Boost mode. By default, the controller works in standalone electric mode; it can also run in automatic transfer, on an external contact.
The electrical side, plainly
At this size, electrical planning matters. Thermo 2000 lists a current of 50 A at 240 V, a 70 A breaker and Cu 6 / Al 4 wire gauge. If the building has a 208 V supply, as some buildings do, output becomes 9 kW at 43.5 A. We review your panel before confirming the quote, so the boiler is added without overloading the electrical service.
The unit is 56 7/16 in high, 22 in in diameter and 25 1/2 in deep with the door. It weighs 280 lb, plus the water in the tank once filled, and operates at a maximum pressure of 30 psi. For the expansion tank, Thermo 2000 recommends a #30 with baseboards or a radiant floor, and a #60 with cast-iron radiators.
How we install it
We start with a free on-site estimate, then give you a written quote that details the boiler, circulator, expansion tank and electrical work. On installation day, we remove the old unit if needed, set the AltSource in place, connect it to the loop and the circuit, mount the outdoor sensor, then fill, purge and set up the system.
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.
Start with an estimate
We serve Montreal, Laval, Longueuil, the North Shore and the South Shore. Ask for your free estimate and written quote; financing is available.
For replacing an electric boiler while moving to renewables
The AltSource 50-12 suits homes that are replacing an aging electric boiler and now rely on an air-to-water heat pump, geothermal or solar for most of their heating. It keeps 48 US gal of water in reserve and adds up to 12 kW as needed.
- Replacing an existing electric boiler on a baseboard loop
- Backup for an air-to-water heat pump in a good-sized house
- Backup for a geothermal system feeding a radiant floor
- Building with a 208 V supply, where output becomes 9 kW
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- Thermo 2000 lists 50 A at 240 V, a 70 A breaker and Cu 6 / Al 4 wire gauge: your panel must have the capacity required.
- At 208 V, output drops to 9 kW (43.5 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.
- Plan for 56 7/16 in of height, 22 in of diameter and 25 1/2 in of depth with the door; weight of 280 lb, plus the water once filled.
- 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
What current does the AltSource 50-12 draw?
According to Thermo 2000, 50 A at 240 V, on a 70 A breaker with Cu 6 or Al 4 wire gauge. We review your electrical panel during the free estimate.
My building has a 208 V supply. What output will I get?
At 208 V, the AltSource 50-12 delivers 9 kW at 43.5 A, according to the manufacturer. We take this into account when choosing the size.
Can I keep my existing baseboard loop?
We examine it during the estimate. The AltSource connects in 1 in male NPT, operates at a maximum pressure of 30 psi, and Thermo 2000 recommends a #30 expansion tank with baseboards.
What comes with the unit?
The 30 psi relief valve, drain valve, temperature and pressure gauge, automatic air vent, heating elements, UltraSmart controller and outdoor sensor.
Does the warranty cover commercial use?
Yes, with different terms: Thermo 2000 covers the tank and coils for 15 years in residential use and 10 years in commercial use, and the electrical and mechanical components for 2 years.
A 12 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.