Packaged Heat Pump System Tosot Rooftop R32 4 Ton | Montreal, Laval, Longueuil, South Shore and North Shore
Backup heat and electrical supply: preparing for a 4 ton
With the TOSOT TK-H04TC/NhA-D(U) model, rated at a nominal capacity of 48,000 BTU/h, two decisions are made well before installation day. The first has to do with backup heat, since the 4 ton accepts the four electric kits TOSOT offers: 5, 10, 15 or 20 kW. The second has to do with the electrical panel, which has to feed the heat pump and, where applicable, the kit selected. This page covers those two subjects, then the duct connection, vertical or horizontal.
First, a reminder of what this unit is. This fully electric Rooftop R32 packaged heat pump gathers the compressor, the coils and the fan in a single outdoor cabinet, connected to the building's duct system. It heats and cools, uses no gas and runs on R-32 refrigerant. TOSOT, a brand of the Gree group, calls it a "DC Inverter Rooftop Ultra Heat Fully Electric Heat Pump".
What the heat pump delivers before any kit
A backup heat kit is sized against what the heat pump delivers on its own. The certified data for the 4 ton is as follows:
- 47,000 BTU/h in heating at 8.3 °C, with a published range of 14,250 to 62,700 BTU/h at that temperature;
- 28,200 BTU/h at -8.3 °C (17 °F), the certified nominal capacity;
- 51,000 BTU/h at -15 °C (5 °F), with a COP of 2.00, measured at maximum compressor speed;
- heating down to -30 °C outdoor (operating range from -30 °C to 24 °C) and ENERGY STAR Cold Climate certification, with an HSPF2 of 8.5.
The value at -15 °C is higher than the one at -8.3 °C, and even higher than the one at 8.3 °C. These figures do not compare directly: the values at 8.3 °C and at -8.3 °C are certified reference capacities, while the value at -15 °C is measured at maximum compressor speed, under the ENERGY STAR Cold Climate criterion. In the same way, the 62,700 BTU/h represent the top of the modulation range published at 8.3 °C, not the certified value. To size backup heat, we therefore look at the capacity the heat pump holds at the design temperature for your area, then at the gap with the building's heat loss. The COP of 2.00 means that at -15 °C, the unit delivers 2.00 units of heat per unit of electricity it uses.
Four backup heat kits offered on the 4 ton
The 5 and 10 kW kits exist across the whole TOSOT range, from the 2 to the 5 ton. The 15 and 20 kW kits are reserved for the 4 and 5 ton models. On the TK-H04TC, the choice is therefore among four options, all sold as options:
- 5 kW: a modest reserve, for a well-insulated building where the heat pump covers most of the heating needs;
- 10 kW: a middle margin, often chosen when the building envelope is average or when you want a safety margin during deep cold;
- 15 kW: for a space whose heat loss in deep cold is well above the capacity of the heat pump;
- 20 kW: for very exposed buildings or when the owner wants a large reserve, provided the electrical panel allows it.
It is worth keeping in mind what these kits are: electric heat strips. They turn electricity into heat without the effect of the heat pump, which draws its heat from the outdoor air. Backup heat therefore acts as a supplement during deep cold, not as the main source, and every kilowatt added is one more load on the panel. That is why we never choose a kit without first looking at the building's electrical service.
The heat pump circuit: MCA 39.1 A and MOCP 45.0 A
The TOSOT specification sheet gives, for the 4 ton, an MCA of 39.1 A and an MOCP of 45.0 A, in 208-230 V single-phase (1 phase, 60 Hz). The MCA, or minimum circuit ampacity, is used to determine the conductor size. The MOCP is the maximum rating of the breaker or the fuses protecting that circuit. Those two values let your electrician plan a compliant circuit for the heat pump itself.
The single-phase supply is an advantage for many small commercial buildings and multiplexes in Montreal, Laval and Longueuil that have no three-phase service. It does not, however, remove the need to check the total capacity of the electrical service, above all if a backup heat kit is added to the project.
Planning the panel with your electrician
Here is the process we follow with the project's electrician before confirming the choice of kit:
- take stock of the capacity of the electrical service and of the loads already connected: water heater, baseboards, kitchen or workshop equipment;
- reserve the heat pump circuit according to the MCA of 39.1 A and the MOCP of 45.0 A;
- add the load of the kit under consideration, 5, 10, 15 or 20 kW, according to the manufacturer's data;
- account for the circuits freed up if the heat pump replaces electric baseboards;
- if the available capacity is not enough, choose a smaller kit or plan an upgrade of the electrical service;
- coordinate the order of the work between the electrician and our installation crew.
That planning avoids ordering a kit the panel could not feed, or having to rework the connection once the unit is set on the roof.
Connecting the 4 ton to vertical or horizontal ducts
The TK-H04TC connects to the ducts in two ways, which leaves room to adapt to the building rather than the other way around. The choice affects where the cabinet goes, the work on the roof and the length of duct to add.
From underneath, on a roof curb
In a vertical connection, supply and return air pass under the unit, through a roof curb whose dimensions TOSOT publishes. The cabinet measures 44 × 44 × 49-1/4 in. (1,120 × 1,120 × 1,250 mm) and weighs 629 lb net, 650 lb gross; it holds 205 oz of R-32 refrigerant. We check the roof structure and the existing curb, if there is one, before confirming this connection method.
From the side, in a horizontal connection
In a horizontal connection, the ducts attach to the side of the cabinet. This option suits cases where the ducts run along the roof or pass through a wall, or where the opening in the roof is not under the chosen location. In both cases, we respect the installation clearances published in the specification sheet and we take the published sound pressure of 68 dB(A) into account so as to keep the unit away from neighbouring windows where possible.
Airflow and static pressure
The centrifugal indoor fan on the 4 ton delivers airflows of 1,350, 900 and 860 CFM (high, medium and low speeds). External static pressure is 0.5 in. as standard and can reach 0.8 in. at most. A short connection, with few elbows, preserves that margin; a long run or a narrow existing duct system uses it up quickly. We measure the duct system before choosing between the vertical and the horizontal connection. The air passes through an aluminum air filter before it is distributed.
The certified data for the TK-H04TC
- AHRI certificate 218795634 and ENERGY STAR certificate 4706809, with the Cold Climate designation.
- SEER2 of 18.0, EER2 of 11.2 and HSPF2 of 8.5 (region IV).
- 47,000 BTU/h in cooling at 35 °C, with a published range of 14,000 to 58,800 BTU/h.
- Cooling at outdoor temperatures from -5 °C to 52 °C.
- High-efficiency DC Inverter technology, vapour injection (EVI) Inverter rotary compressor and electronic expansion valve.
- Control by a standard 24 V thermostat from another manufacturer or by a TOSOT RS485 thermostat; standard XE7C-23/H controller.
To compare this model with other capacities or with the other brands of the Gree group, see our packaged heat pumps page: there you will find the Rooftop R32 models we install, from the 2 to the 5 ton.
Have your panel and your ducts assessed
We install the 4 ton TOSOT packaged heat pump in Montreal, in Laval, in Longueuil, on the North Shore and on the South Shore, and we plan the backup heat kit, the electrical circuit and the duct connection with you. 100% free on-site estimate anywhere in Montreal, Laval, Longueuil, the North Shore and the South Shore: call us at 514 316-2973. AirGreen inc., RBQ licence 5645-9605-01.