Packaged Heat Pump System Gree Rooftop R32 4 Ton | Montreal, Laval, Longueuil, South Shore and North Shore
A 4 ton is planned in three parts: the air, the power and the roof
The Gree Rooftop R32 packaged heat pump in the 4 ton size (48,000 BTU/h nominal capacity, 47,000 BTU/h certified in cooling) heats and cools stores, offices and buildings whose load goes beyond what the 2 or 3 ton sizes cover. At this capacity, a successful installation rests on three things that are decided well before the work starts: the duct system has to carry the airflow, the electrical panel has to take the circuit, and the roof has to support the unit.
At AirGreen, we take up these three parts right at the estimate, with you, with your electrician and, if needed, with the professional responsible for the building structure. Everything is gathered in a single outdoor cabinet (compressor, coils and fan); the unit is all electric, ENERGY STAR Cold Climate certified, and connects to the duct system already in place or still to be built. We install it in Montreal, in Laval, in Longueuil, on the North Shore and on the South Shore.
Part one: air distribution
The fan on the 4 ton moves 1,350 CFM at high speed, 900 CFM at medium speed and 860 CFM at low speed. That airflow has to be able to travel through the ducts without the resistance becoming excessive, otherwise part of the unit's capacity never reaches the rooms.
Understanding static pressure
External static pressure is the resistance the air meets outside the unit: ducts, elbows, grilles, filters and dampers. Gree publishes a value of 0.50 in. for this model, within an operating range of 0 to 0.8 in. A duct system that is too restrictive cuts the real airflow, leaves rooms lukewarm in winter and areas poorly cooled in summer, and makes the fan work in poor conditions.
What we measure on site
- The cross-section of the main ducts and the branches, compared with the airflow of 1,350 CFM.
- The number and the size of the supply and return air grilles.
- The static pressure of the existing duct system, to place it within the range of 0 to 0.8 in.
- Leaks and uninsulated sections, above all those that cross an attic or an unheated space.
If the duct system was designed for a smaller unit, we tell you what corrections to plan for, grille by grille or duct by duct, before you make a decision.
Part two: the electrical circuit
The 4 ton is powered in 208-230 V single-phase, 60 Hz. That is an advantage for buildings with no three-phase service: there is no need to have one installed to take the unit. Two values published by Gree guide your electrician:
- MCA of 39.1 A: the minimum circuit ampacity, used to choose the conductor size.
- MOP of 45 A: the maximum overcurrent protection, that is the maximum rating of the breaker or the fuses.
Before installation, we check with your electrician the capacity available at the panel, the room for a new breaker, the cable route up to the roof and the location of the disconnect near the unit. When the panel is already loaded, it is better to know at the estimate than on the day of the work: a service upgrade is planned, it is not improvised.
Part three: the roof and handling
The cabinet on the 4 ton measures 44 × 44 × 49-1/4 in. (1,120 × 1,120 × 1,250 mm) and weighs 628.3 lb net. That weight is concentrated on a small area. We therefore pass on the weight and the dimensions of the unit so the capacity of the structure can be confirmed, by an engineer if needed, before the work.
We also plan the lift up to the roof, the duct run between the unit and the building, access for maintenance and the clearance around the cabinet. The published sound pressure, 68 dB(A), also comes into the picture: where possible, we keep the unit away from windows, terraces and the building's air intakes.
The control wiring
On a roof, the unit often sits far from where the control is meant to go. Gree's universal control connection offers two possibilities: two-wire communication with the GREE controller supplied, or a standard 24 V connection to a thermostat. The communication distance can reach 30 m (98.5 ft.), and polarity-free communication avoids reversed-wire errors. Central control is provided for, and remote control is possible with a gateway offered as an option.
Preparing for your estimate
So the visit covers the three parts in one go, have on hand, if possible:
- a photo of the electrical panel and its nameplate;
- the building plans or a sketch of the duct system, if they exist;
- the information on roof access (ladder, hatch or stairs);
- the details of the current unit, if there is one, and of its location.
That information lets us arrive with the right questions and give you a recommendation that takes the whole building into account: heating and cooling capacity, airflow, electrical supply and structure. If one of the parts calls for work beforehand, you know it before you commit.
Certified performance, from a heat wave to deep cold
Once the air, the power and the roof are planned, the unit can deliver the performance it is certified for. Here is the data for the 4 ton:
- Certified cooling at 35 °C: 47,000 BTU/h, with an EER2 of 11.2 and a SEER2 of 18.0.
- Heating at 8.3 °C: 47,000 BTU/h.
- Heating at -8.3 °C (17 °F): 28,200 BTU/h, certified nominal capacity.
- Heating at -15 °C (5 °F): 51,000 BTU/h at maximum compressor speed, with a COP of 2.00.
- HSPF2 of 8.5 (region IV).
- Operating range: heating down to -30 °C (and up to 24 °C outdoor), cooling from -5 °C to 52 °C.
- AHRI no. 216763053 and ENERGY STAR certificate no. 4006773.
The capacities at -8.3 °C and at -15 °C do not compare directly. The first is the certified nominal capacity; the second is measured at maximum compressor speed, under the criterion of the ENERGY STAR Cold Climate designation, hence the higher figure. The COP of 2.00 at -15 °C means the unit delivers two units of heat for every unit of electricity it uses at that temperature.
What Gree built into the unit
The "Ultra-Heat" technology combines two-stage, twin-cylinder compression with hot gas injection, for cold-weather heating performance. Gree adds to it high-efficiency DC Inverter technology, anti-corrosion and dust-proof construction, multiple protections, multi-parameter regulation, zero-wind start-up and an emergency operating mode. The refrigerant is R-32, with a charge of 204.6 oz. To compare this size with the other capacities and brands, see our packaged heat pumps page.
An estimate that covers the air, the power and the roof
We assess your ducts, your panel and your roof in a single visit, then we give you a clear recommendation for the installation of your packaged heat pump. 100% free on-site estimate anywhere in Montreal, Laval, Longueuil, the North Shore and the South Shore. Call AirGreen at 514 316-2973. AirGreen inc., RBQ licence 5645-9605-01.