Converting to Variable Refrigerant Flow (VRF) from an existing Carrier Rooftop Packaged DX unit has been made much easier with the Toshiba Carrier 40QQ VRF Rooftop Packaged Unit. The Carrier 40QQ VRF units come in 3, 4 and 5 ton capacities.
You can replace the existing old curb mounted rooftop Carrier packaged unit with a new Variable Refrigerant Flow (VRF) rooftop unit that fits on the same old curb. This saves the hassle of tearing up the roof and removing the curb, while providing you with the benefit of using the existing roof penetration and ductwork for the new VRF system. Just rig off the old Carrier DX packaged unit and rig onto the existing curb the new VRF packaged unit.
The new Carrier 40QQ VRF rooftop unit will weigh less than the existing DX Packaged unit because the new Variable Refrigerant Flow (VRF) rooftop unit doesn’t contain the compressor and outdoor coil. You will need to find a separate location for the outdoor unit, preferable on ground level. This will help in most jurisdictions that will be looking to see if you have increased the weight that the structure must support. In some jurisdictions the structural codes have gotten more stringent which would require reinforcing the structure to support a new DX unit. This could add additional cost to your project.
You will need to run ACR copper piping from the location where the outdoor unit will sit up to the new Toshiba Carrier 40QQ VRF Rooftop unit.
Carrier 40QQ Advantages & Disadvantages
- Cost Savings & Advantages
- Can be used with existing Carrier Packaged Unit Curb (3 to 5 Tons)
- Avoids possible structural upgrades because VRF unit weighs less
- Allows the use of the existing ductwork without modifications
- More efficient direct drive ECM motor
- Can convert a downflow (vertical) to a horizontal supply & return duct configuration
- Selector box for heat recovery systems can be mounted inside rooftop unit
- No need to hang fan coils inside building, avoiding disruption to tenants
- Optional economizer (T-24 Compliant) Honeywell Controller
- Optional electrical heater (not an advantage in some states due to electrical rates)
- Diversity factor possible where total indoor tonnage is greater than outdoor unit size
- Additional Cost & Disadvantages
- New electrical to new Outdoor Unit
- New ACR Copper piping from Outdoor Unit to Rooftop VRF unit
- Requires a concrete pad or platform for new Outdoor Unit
- Initial cost is more than direct replacement of existing packaged DX unit
The Toshiba Carrier 40QQ is available in 208/230v 1-ph or 460v-1ph power
Carrier 40QQ Performance Data
- 3-Ton Unit (40QQ – 036AAA3 – 0A0)
- 36,000 Btuh – Cooling Capacity
- 38,000 Btuh – Heating Capacity
- 1,050 CFM – Cooling & Heating
- Weight – 364 Lbs, add for economizer & curb weight
- External Static Pressure (Max) 1.65 WG (Factory set at 0.15)
- 4-Ton Unit (40QQ – 048AAA3 – 0A0)
- 48,000 Btuh – Cooling Capacity
- 52,000 Btuh – Heating Capacity
- 1,350 CFM – Cooling
- 1,750 CFM – Heating
- Weight – 385 Lbs, add for economizer & curb weight
- External Static Pressure (Max) 1.38 WG (Factory set at 0.20)
- 5-Ton Unit (40QQ – 060AAA3 – 0A0)
- 60,000 Btuh – Cooling Capacity
- 66,000 Btuh – Heating Capacity
- 1,750 CFM – Cooling & Heating
- Weight – 394 Lbs, add for economizer & curb weight
- External Static Pressure (Max) 1.15 WG (Factory set at 0.20)
For installation of the Selector Box in a Heat Recovery system within the Carrier 40QQ VRF Rooftop unit, you will need to mount it, connect the electrical and control wire harnesses provide in addition to brazing in the piping connection. Most of the parts you need are provided with the Heat Recovery Selector box kit.
Get a copy of the Toshiba Carrier 40QQ VRF Engineering manual.