THERMO 2000 AltSource 70 Thermal Mass Electric Boiler | 27 kW - 240V
A 27 kW Thermo 2000 thermal mass electric boiler: six 4.5 kW elements and a 71 US gal tank to back up a renewable heat source.
Model numberALTSOURCE70-27
514 316-2973 · sales@airgreen.ca
Quick facts
Six output stages and 71 gallons of water in reserve to back up your geothermal system or heat pump
Who the 27 kW AltSource 70 is for
The 27 kW AltSource 70 delivers 92,124 BTU/h at 240 V. It belongs to Thermo 2000’s AltSource line, thermal mass electric boilers whose role is to back up a main renewable-energy system. The 70 version keeps 71 US gallons of water in its tank, versus 48 for the AltSource 50.
This model is aimed mainly at homes heated with hot water by a geothermal system or an air-to-water heat pump, when the backup must go beyond the smaller sizes in the series. It also suits a homeowner preparing a geothermal project: set to standalone electric mode, its default, the boiler heats on its own until the main source is commissioned.
Output that follows the weather
What sets this size apart is its six 4.5 kW elements spread over six stages. The T2 UltraSmart controller, linked to the supplied outdoor sensor, modulates output and water temperature based on the outdoor temperature. On a cool November day, a few elements are enough; in the middle of January, the boiler can climb to its full 27 kW. Warm weather shutdown avoids needless cycles at the start and end of the season, and Boost mode is there when needed.
For distribution, the AltSource serves radiant floors, hot water baseboards and radiators. Thermo 2000 recommends a #60 expansion tank for the first two and a #90 for cast iron radiators.
Domestic water as a bonus
The large tank can also serve domestic water. Thermo 2000 offers an optional 26.2 sq ft parallel copper coil heat exchanger, meeting the NSF 61 standard, that heats or preheats water at up to 12 gpm. It connects with 3/4 in male sweat fittings and handles a pressure of 125 psi.
What AirGreen’s installation covers
We start with a free on-site estimate. This size calls for a 150 A breaker and copper wire gauge 1 or aluminum gauge 00 at 240 V, so we check your electrical service first. If the building is supplied at 208 V, Thermo 2000 states that the boiler delivers 20.3 kW. We also look at the floor location, since the unit is 24 in in diameter and weighs 380 lb.
You receive a detailed written quote. Our technicians then install the boiler, connect it to the electrical circuit and the hot water loop, fill and purge the system, then set the controller for your main source and distribution 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.
Take the next step
Our crews travel to Montreal, Laval, Longueuil, the South Shore and the North Shore.
Book your free estimate and receive a written quote for your AltSource; financing is available.
Electric backup for renewable-energy heating
Thermo 2000 designs the AltSource as the backup source for a main renewable-energy system. The 27 kW model combines the AltSource 70’s 71 US gal tank with six 4.5 kW elements, for backup that ramps up in steps.
- Backup for a geothermal system
- Backup for an air-to-water heat pump
- Supplementing a solar thermal system
- Heating on its own in standalone electric mode until the renewable source is added
- Preheating domestic water with the optional coil heat exchanger
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, 60 Hz power supply on a 150 A breaker; suggested wire gauge at 240 V: copper 1 or aluminum 00.
- At 208 V, Thermo 2000 lists an output of 20.3 kW and a current of 97.9 A.
- Floor-standing unit, 24 in in diameter and 28 in deep with the door, weighing 380 lb: save it a spot in the mechanical room.
- Maximum working pressure of 30 psi (207 kPa). Required clearances are those in the installation manual.
- Expansion tank recommended by Thermo 2000: #60 for baseboards or radiant floors, #90 for cast iron radiators.
- The domestic water heat exchanger is an option: it is not part of the base unit.
- 30 psi (207 kPa) relief valve
- Drain valve
- Temperature and pressure gauge
- Automatic air vent
- Heating elements (6 x 4.5 kW)
- UltraSmart controller
- Outdoor sensor
Manufacturer documents
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Frequently asked questions
What do six stages change compared with four?
With six 4.5 kW elements, output is adjusted in smaller steps than with 6 kW elements. The T2 UltraSmart controller modulates output based on the outdoor temperature and shuts down in warm weather.
Does the AltSource work with geothermal?
Yes. Thermo 2000 names geothermal among the main systems the AltSource backs up, along with air-to-water heat pumps and solar.
Which breaker and wire does it need?
Thermo 2000 lists a 150 A breaker and copper wire gauge 1 or aluminum gauge 00 at 240 V. We check your electrical service before confirming the size.
What comes with the boiler?
The 30 psi relief valve, drain valve, temperature and pressure gauge, automatic air vent, heating elements, UltraSmart controller and outdoor sensor.
What warranty does Thermo 2000 offer?
The tank and coils are covered for 15 years in residential use and 10 years in commercial use; electrical and mechanical components for 2 years.
Your 27 kW backup boiler, 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.