THERMO 2000 Mini BTH 12 Electric Boiler | 12 kW - 240V
The Mini BTH 12 is the largest size in the series: 12 kW on two 6 kW elements, in the same compact wall-mounted cabinet as the smallest models.
Model numberMINI BTH 12
514 316-2973 · sales@airgreen.ca
Quick facts
12 kW of hot water heat in the same small wall-mounted cabinet
The top of the Mini BTH series
Thermo 2000 offers the Mini BTH from 3 to 12 kW, and every size shares the same cabinet: 1 US gal of water, 47 lb shipping weight, dimensions of 21 1/2 x 8 7/8 x 8 3/4 in. The Mini BTH 12 is the largest size. Two 6 kW elements, spread over two stages, deliver 40,944 BTU/h at 240 V. The aquastats bring them on according to demand, and an indicator light per element shows which one is heating.
It accepts a flow of 8.2 US gpm at a 10 °F difference, or 4.1 US gpm at 20 °F, with negligible pressure drop according to the manufacturer. Water can be set from 50 °F to 190 °F (10 °C to 90 °C), which suits radiators as well as radiant floors and hydronic baseboards. Thermo 2000 also presents it as backup for a heat pump, a geothermal or a solar system, quiet and with no GHG emissions.
An entire small house, without a floor-standing boiler
A single-storey home in Longueuil heated by radiant floor, a large plex unit in Montreal with its original radiators, a small well-insulated house on the South Shore: at 12 kW, the Mini BTH can often carry all the heating for a building of that size. Mounted on the wall, it frees the space the old electric boiler used to take. If the heat loss calculation goes beyond 12 kW, Thermo 2000 offers higher-capacity electric boilers, and we tell you so at the estimate.
The electrical panel first
This is the first thing to check. At 240 V, the Mini BTH 12 draws 50.0 A; Thermo 2000 specifies a 70 A breaker and Cu 6 or Al 4 wire. In a panel already taken up by the range, the dryer and the water heater, this load needs room. In a building supplied at 208 V, output falls to 9 kW (43.5 A): we take that into account before choosing this size. The Mini BTH has no outdoor sensor, and its maximum working pressure is 30 psi (207 kPa).
What AirGreen does
After a free on-site estimate, you receive a written quote that specifies the circulator and the expansion tank, which are not supplied with the boiler, and any panel work. Our technicians remove the old electric boiler, mount the Mini BTH, connect its four 3/4 in NPT connections to the system, install the supplied 30 psi relief valve and temperature and pressure gauge, wire the appliance and the thermostat, then fill, purge and check each zone with you.
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. Thermo 2000 warrants the tank for 15 years and the electrical and mechanical components for 2 years.
Plan your installation
We install the Mini BTH in Montreal, Laval, Longueuil, on the North Shore and on the South Shore. The on-site estimate is free, the quote is in writing, and financing is available.
The largest Mini BTH, to heat an entire small house
The Mini BTH 12 heats the water of a hydronic circuit with two 6 kW elements, brought on in stages according to demand. Thermo 2000 fits it in the same wall-mounted cabinet as the other sizes in the series.
- Small house heated entirely by radiant floor or radiators
- Large plex unit heated by radiators
- Replacing a floor-standing electric boiler with a wall-mounted model
- Backup for a heat pump, a geothermal or a solar system
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- Dedicated 240 V single-phase circuit: 50.0 A, 70 A breaker and Cu 6 / Al 4 wire, according to Thermo 2000. Panel capacity must be checked.
- At 208 V, output falls to 9 kW (43.5 A).
- No circulator or expansion tank included: they are chosen for the system.
- Aquastat control, no outdoor sensor; water adjustable from 50 °F to 190 °F (10 °C to 90 °C).
- Maximum working pressure of 30 psi (207 kPa).
- 30 psi relief valve
- Drain valve
- Temperature and pressure gauge
- Installation manual
Manufacturer documents
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Frequently asked questions
Can a Mini BTH 12 heat a whole house?
A small, well-insulated house, often. It delivers 40,944 BTU/h at 240 V. The heat loss calculation done during the free estimate confirms whether 12 kW is enough or whether a higher-capacity boiler is needed.
What happens at 208 V?
Output becomes 9 kW (43.5 A). In a building supplied at 208 V, we take that into account before choosing this model.
What breaker is needed?
A 70 A breaker at 240 V with Cu 6 or Al 4 wire, according to Thermo 2000; the appliance draws 50.0 A. That is a significant load for a panel that is already busy: we check it on site.
Is it larger than the other Mini BTH models?
No. Thermo 2000 offers the series from 3 to 12 kW in the same cabinet: 1 US gal of water, 47 lb shipping weight and dimensions of 21 1/2 x 8 7/8 x 8 3/4 in.
What warranty does Thermo 2000 offer?
15 years on the tank and 2 years on electrical and mechanical components, in Canada and the United States.
A 12 kW Mini BTH, 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.