HVAC installations are characterized by the wide range of system configurations available and design decisions have a significant impact on the final cost of the project. This case study provides a detailed cost comparison for the following three options:
1. VRF HVAC (LG) system with balcony heat pump and indoor fan coil units for two zones.
2. VRF HVAC (LG) system with heat pump on the roof and indoor fan coil units for two zones.
3. Vertical packaged unit (Magic-Pak) on balcony, with electric air conditioning and gas heating.
The three system configurations described above were analyzed for three apartment layouts, resulting in nine scenarios. Therefore, we tried to take into account several options that are suitable for both wealthy families and people with a limited budget.
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The apartments considered have the following characteristics:
- One bedroom, 1,271 square feet.
- Two bedrooms, 1,426 square feet.
- Three bedrooms, 1,838 square feet.
The rooftop VRF system is the most expensive option for the three apartment layouts, followed by the balcony VRF system. The lowest installation cost is achieved with Magic-Pak M Series packaged vertical units.
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Cost Summary of the Three HVAC Options
The following table provides the mechanical, electrical, and plumbing costs for each scenario in the case study. It's important to note that the table uses actual quotes from New York contractors.
Packaged vertical units lead to more affordable HVAC installations for several reasons:
- VRF options utilize heat pumps and fan coils connected to long refrigerant lines, while the Magic-Pak unit consolidates equipment and eliminates refrigerant connections.
- The Magic-Pak unit does not require condensate drain connections as it utilizes a porch floor drain.
- VRF systems require separate electrical circuits for heat pumps and fan coils, while the Magic-Pak unit uses only one circuit. The rooftop VRF system has the highest electrical cost due to the length of the circuit that powers the heat pumps.
- Because the Magic-Pak unit uses gas heating, it carries higher gas piping costs compared to VRF options. However, these additional costs are offset by savings on all other MEP installations.
- The gas pipe is only suitable for stoves when VRF options are used, hence its lower cost.
The following sections provide an individual cost comparison for mechanical, electrical and plumbing installations in each of the scenarios considered.
Mechanical Installation: Overview and Cost
The following drawings show the location of the mechanical equipment of the VRF system with heat pumps on the apartment balconies. Outdoor heat pumps are labeled ACCU (air-cooled condensing unit), while indoor fan coils are labeled AC.
In all three apartment layouts, the VRF system uses an external heat pump and two internal fan coil units. The indoor equipment locations are the same in the rooftop VRF option, but the system becomes more expensive because the refrigerant lines and electrical circuits are longer.
Magic-Pak units result in a simpler mechanical layout, as shown in the following drawings. The system uses a single unit rather than separate condensers and fan-coils, and there is no need to install refrigerant lines:
As the Magic-Pak installation uses less equipment and is more compact, it has the lowest cost among the three options. Consider that a compact installation not only provides savings on equipment and materials, but also savings on skilled labor.
Electrical Installation: Overview and Cost
While mechanical installation represents the majority of the project scope and cost, there are also significant differences between the electrical installations in each option. The Magic-Pak system also has the lowest electrical costs, requiring only one circuit, while VRF options require three circuits.
The heat pump circuits become even longer with the VRF rooftop system, as they must reach the location indicated in Figure 03. Although the sizes of the ducts and wiring do not change, the electrical installation becomes more expensive due to the extra distance traveled.
When Magic-Pak units are used, there is no need to install separate circuits for fan-coil units. The installation uses a single circuit between the apartment's load center and the HVAC unit on the balcony. Electrical costs for all nine scenarios are compared in the following table.
Plumbing and gas installation: overview and cost
The Magic-Pak option eliminates condensate drain connections between fan coils and heatsinks, reducing plumbing costs. Since packaged units are installed on the balcony, they use a simple floor drain.
The gas piping is the only part of the project that is more expensive, as the Magic-Pak unit specified uses gas burners for space heating. On the other hand, VRF heat pumps only work with electricity in both operating modes, with the stove being the only equipment that consumes natural gas.
As indicated in the following table, gas piping is the only element that is more expensive with packaged vertical units. However, the savings on all other system components are much greater than the additional cost of the gas piping:
Final cost comparison
Vertical units are the most cost-effective HVAC option for all three apartment layouts, as indicated in the following chart:
In this case study, most MEP installations cost less when packaged vertical units are used. This happens because the mechanical equipment is consolidated, using only one electrical circuit and one drain on one floor per apartment. The only part of the project that is more expensive is the gas piping; Magic-Pak units use gas heating, while VRF heat pumps use electricity for heating and cooling.
A professional HVAC project is the first step to obtaining reliable information about a project's costs. Once a detailed design is available, contractors can provide accurate quotes for the HVAC project. Cost estimates based on rules of thumb are not recommended: they lead to oversized equipment that is more expensive than necessary, and system components are easily lost without a proper design procedure.
