THERMO 2000 AltSource 70 Thermal Mass Electric Boiler | 20 kW - 240V
The 20 kW AltSource 70 brings together 71 US gal of water and four 5 kW elements: an electric backup to plan from the drawings of a home heated by a renewable source.
Model numberALTSOURCE70-20
514 316-2973 · sales@airgreen.ca
Quick facts
A 20 kW backup with 71 US gal of water, to build into the plans of your new or renovated home
Planning the backup from the design stage
When you build or renovate from top to bottom, heating is decided early. Projects that rely on an air-to-water heat pump, geothermal or solar need a backup source, and that is the role Thermo 2000 gives the AltSource. For a good-sized home, the 70-20 version combines the AltSource 70’s large 71 US gal tank with 20 kW at 240 V, or 68,240 BTU/h. The manufacturer presents the AltSource as the only high water volume electric boiler on the market.
What the AltSource 70-20 brings
Its output is split between four 5 kW elements, controlled in four stages. The T2 UltraSmart controller, supplied with its outdoor sensor, modulates output and water temperature to the weather, 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. Water is heated from 50 °F to 190 °F (10 °C to 88 °C), which suits a radiant floor as well as baseboards and radiators.
As an option, Thermo 2000 offers a 26.2 sq ft parallel copper coil heat exchanger to heat or preheat domestic water, up to 12 gpm and 125 psi. In new construction, this is the ideal time to add it, since the piping is planned along with everything else. Thermo 2000 covers the tank and coils for 15 years in residential use, and the electrical and mechanical components for 2 years.
The data to build into the plans
On the electrical side, Thermo 2000 lists a 110 A breaker and Cu 3 / Al 2 wire gauge at 240 V single phase. In a building with a 208 V supply, output becomes 15 kW at 72.5 A. These values must be included in the sizing of the home’s electrical service.
On the mechanical room side, the unit measures 24 in in diameter and 28 in deep with the door, and weighs 380 lb before filling. It connects to the loop in 1 1/4 in male NPT and operates at a maximum pressure of 30 psi. The manufacturer recommends a #60 expansion tank with a radiant floor or baseboards, and a #90 with cast-iron radiators.
Our role in your project
Whether your site is in Longueuil, on the South Shore or elsewhere in Greater Montreal, we do a free on-site estimate and give you a written quote that specifies the boiler, the domestic water option if you choose it, the circulator, the expansion tank and the electrical work. At the installation stage, our technicians set the unit in place, connect it to the loop and the circuit, mount the outdoor sensor and supplied accessories, then fill, purge and set up the system.
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 talk about your plans
We serve Montreal, Laval, Longueuil, the North Shore and the South Shore. Ask for your free estimate and written quote; financing is available.
The backup for a new or fully renovated home
The AltSource 70-20 fits projects that rely on an air-to-water heat pump, geothermal or solar and plan a mechanical room from the design stage. It adds up to 20 kW in four stages and, with the optional heat exchanger, heats or preheats domestic water.
- New construction heated by a radiant floor and an air-to-water heat pump
- Major renovation that replaces the whole heating system
- Large geothermal home that also wants to preheat its domestic water
- Project where the electrical circuit can be planned from the start
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: 110 A breaker and Cu 3 / Al 2 wire gauge, according to Thermo 2000. At 208 V, output drops to 15 kW (72.5 A).
- Unit of 380 lb before filling, 24 in in diameter and 28 in deep with the door: the mechanical room and its floor must be planned accordingly.
- The domestic water heat exchanger is an option to specify at the quote stage.
- 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.
- 1 1/4 in male NPT fittings; 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
When should the AltSource be planned during construction?
As early as possible. The 110 A circuit, the location of a 380 lb unit and the connection to the loop are easier to plan before the walls are closed and the basement is finished.
How does the domestic hot water option work?
Thermo 2000 offers a 26.2 sq ft parallel copper coil heat exchanger that heats or preheats domestic water. It accepts up to 12 gpm and 125 psi, with 3/4 in male sweat connections (NSF 61).
What output do you get at 208 V?
15 kW at 72.5 A, according to the manufacturer. At 240 V, the unit delivers 20 kW.
How does it differ from the 20 kW AltSource 50?
The output is the same; the AltSource 70 holds 71 US gal of water instead of 48 US gal. In new construction where space is planned ahead, the larger reserve is often easy to fit.
What warranty does Thermo 2000 offer?
15 years on the tank and coils in residential use, 10 years in commercial use, and 2 years on electrical and mechanical components and accessories.
A 20 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.