THERMO 2000 AltSource 70 Thermal Mass Electric Boiler | 12 kW - 240V
The 12 kW AltSource 70 is a 71 US gal thermal mass electric boiler with two 6 kW elements, for homes as well as small commercial buildings heated by a renewable source.
Model numberALTSOURCE70-12
514 316-2973 · sales@airgreen.ca
Quick facts
A 12 kW electric backup with 71 US gal of water, for homes and small businesses alike
Residential or light commercial
A North Shore workshop whose slab is heated by geothermal, a large Laval house with a radiant floor and an air-to-water heat pump, a small commercial space with solar thermal collectors: these projects share a renewable heat source that needs an electric backup. Thermo 2000’s AltSource 70-12 meets that need, and the manufacturer warrants it for both uses: 15 years on the tank and coils in residential use, 10 years in commercial use, and 2 years on electrical and mechanical components.
What the AltSource 70-12 contains
It is a thermal mass electric boiler, which Thermo 2000 presents as the only high water volume electric boiler on the market. Its tank holds 71 US gal of water. Its 12 kW output at 240 V, or 40,944 BTU/h, comes from two 6 kW elements that come on in two stages. Water is heated from 50 °F to 190 °F (10 °C to 88 °C), a range that covers radiant floors as well as baseboards and radiators.
The T2 UltraSmart controller, supplied with its outdoor sensor, modulates output and water temperature on the outdoor temperature, shuts heating off in warm weather and offers a Boost mode. It runs in standalone electric mode by default or in automatic transfer on an external contact, and provides 24 V power for accessories.
Installation in an existing building
On the electrical side, Thermo 2000 lists 50 A at 240 V, a 70 A breaker and Cu 6 / Al 4 wire gauge. If your space has a 208 V supply, output becomes 9 kW at 43.5 A: this is a point we check from the first visit.
On the hydronic side, the AltSource 70 connects in 1 1/4 in male NPT and operates at a maximum pressure of 30 psi. The manufacturer recommends a #60 expansion tank with baseboards or a radiant floor, and a #90 with cast-iron radiators. The unit weighs 380 lb before filling and measures 24 in in diameter and 28 in deep with the door: the location and access must be planned accordingly.
AirGreen’s support
The on-site estimate is free. We look at the main source, the loop, the electrical supply and the space, then provide a written quote that specifies the boiler, circulator, expansion tank and electrical work. Our technicians install the unit, connect it, mount the outdoor sensor and supplied accessories, fill and purge the system, then set the controller.
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.
Tell us about your building
We serve Montreal, Laval, Longueuil, the North Shore and the South Shore. Ask for your free estimate and receive a written quote; financing is available.
From the home to the commercial space
The AltSource 70-12 serves as the electric backup of an air-to-water heat pump, a geothermal system or solar collectors. Thermo 2000 warrants it for residential as well as commercial use, which makes it an option for a workshop or a small commercial space as much as for a large house.
- Workshop or small commercial space with a heated slab tied to geothermal
- Large house with radiant floor heating and an air-to-water heat pump
- Space with a 208 V supply, where output becomes 9 kW
- Solar thermal system that needs a substantial electric backup
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: 50 A, 70 A breaker and Cu 6 / Al 4 wire gauge, according to Thermo 2000. At 208 V, output drops to 9 kW (43.5 A).
- The manufacturer’s documents do not mention a 0-10 V signal, Wi-Fi or a building management system connection; the controller offers a 24 V output for accessories.
- Unit of 380 lb (plus the water once filled), 24 in in diameter and 28 in deep with the door.
- Recommended expansion tank: #60 for baseboards or a radiant floor, #90 for cast-iron radiators. The tank and circulator are not among the supplied parts.
- 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
Can it be installed in a commercial space?
Thermo 2000 provides for this in its warranty: 15 years on the tank and coils in residential use, 10 years in commercial use, and 2 years on electrical and mechanical components. We confirm the size based on the space’s needs.
How is the output split?
The 12 kW comes from two 6 kW elements, over two stages. The T2 UltraSmart controller modulates output and water temperature on the outdoor temperature.
What output do you get at 208 V?
9 kW at 43.5 A, according to Thermo 2000. At 240 V, the unit delivers 12 kW at 50 A.
Can it be connected to a building management system?
Thermo 2000’s documents for the AltSource do not mention it, nor a 0-10 V signal or Wi-Fi. The controller runs in standalone electric mode or in automatic transfer on an external contact.
Can you install it?
Yes. We set the boiler in place, connect it to the loop and the electrical circuit, mount the outdoor sensor and supplied accessories, then fill, purge and set up the system.
A 12 kW AltSource 70, 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.