THERMO 2000 AltSource 50 Thermal Mass Electric Boiler | 20 kW - 240V
The 20 kW AltSource 50 fits four 5 kW elements and 48 US gal of water in a unit 22 in in diameter, as the backup of a renewable heating system.
Model numberALTSOURCE50-20
514 316-2973 · sales@airgreen.ca
Quick facts
20 kW in a unit 22 in in diameter: the AltSource 50 for mechanical rooms where every inch counts
High output, small footprint
In many basements, the mechanical room is squeezed between the stairs, the electrical panel and the water heater. Thermo 2000’s AltSource 50-20 takes this into account: it fits 20 kW at 240 V, or 68,240 BTU/h, and a 48 US gal tank in a unit 22 in in diameter and 25 1/2 in deep with the door, for 56 7/16 in of height.
Its output comes from four 5 kW elements, controlled in four stages by the T2 UltraSmart controller. With the supplied outdoor sensor, the controller 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.
Who should choose it
The AltSource is a thermal mass electric boiler that Thermo 2000 designs as the backup of a renewable-energy heating system, and presents as the only high water volume electric boiler on the market. The 20 kW size is meant for homes with a high heating demand, for example a large property on the North Shore or in Laval heated by geothermal or an air-to-water heat pump, with hot-water baseboards or a radiant floor. It is also a good candidate to replace an existing boiler where space does not allow a wider unit.
What to plan before the work
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. At this level, the electrical service must be assessed carefully, and we do so from the estimate.
On the hydronic side, the unit connects in 1 in male NPT and operates at a maximum pressure of 30 psi. The manufacturer recommends a #30 expansion tank with baseboards or a radiant floor, and a #60 with cast-iron radiators. The unit weighs 280 lb, plus the water in the tank once filled.
What our installation covers
The on-site estimate is free and the written quote specifies the boiler, circulator, expansion tank and electrical work. On installation day, our technicians remove the old unit if needed, set the AltSource 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 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.
Take the first step
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.
Plenty of output in little space
The AltSource 50-20 is aimed at homes with a high heating demand and a small mechanical room. It backs up an air-to-water heat pump, a geothermal system or solar collectors with 20 kW split into four stages.
- Replacing a boiler in a cramped mechanical room
- Large house heated by geothermal with limited basement space
- Backup for an air-to-water heat pump feeding hot-water baseboards
- Building with a 208 V supply, where output becomes 15 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 a 110 A breaker and Cu 3 / Al 2 wire gauge at 240 V single phase: the electrical service must allow for it.
- At 208 V, output drops to 15 kW (72.5 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.
- Weight of 280 lb, plus the water in the tank once filled; 1 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
How much space is needed?
The unit is 22 in in diameter, 25 1/2 in deep with the door and 56 7/16 in high. Add the clearances Thermo 2000 requires, which we check on site.
What breaker is needed?
Thermo 2000 lists a 110 A breaker and Cu 3 or Al 2 wire gauge, at 240 V. We review your electrical service before confirming the quote.
What does it deliver at 208 V?
15 kW at 72.5 A, according to the manufacturer.
How are the four elements controlled?
The 20 kW is split into four 5 kW elements over four stages. The T2 UltraSmart controller modulates output and water temperature on the outdoor temperature, and shuts heating off in mild weather.
AltSource 50 or AltSource 70 at 20 kW?
The output is identical; the AltSource 70 holds 71 US gal of water instead of 48 US gal, in a larger and heavier unit. When space is short, the AltSource 50 is often the right answer.
A 20 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.