Daikin DH6 Heat Pump Installation with Full Duct Replacement
Cold Cloud Mechanical completed a full HVAC replacement in Alhambra with a 4-ton Daikin DH6 variable-speed heat pump, matched ECM air handler, Daikin One air cleaner, and a full R-8 duct replacement designed and balanced room by room.
A full-system replacement designed around airflow first
This Alhambra project covered a full HVAC replacement on a single-family home: a new outdoor unit, a new indoor air handler, and a complete duct rebuild driven by room-by-room Manual D design.
The goal was straightforward but not trivial: deliver the right airflow to every room, eliminate the supply gaps the old system had, and bring the attic installation up to current code while the system was being rebuilt.
Why the duct system had to be rebuilt with the equipment
Many homes in Alhambra carry duct systems that were sized to older equipment and looser standards. A modern variable-speed inverter system cannot perform properly if it is connected to undersized ducts and a restrictive return.
The old ducts limited delivered capacity
Dropping a modern inverter system onto restrictive ductwork can prevent the equipment from modulating properly and leave the homeowner paying for capacity the rooms never actually receive.
Two rooms needed additional supply airflow
The dining room and living room were underserved, so new supply branches with takeoffs, flex runs, boots, and opposed blade damper grilles were added.
What Cold Cloud Mechanical completed
The project included full duct removal and replacement, Manual D duct design, new supply branches, return upsizing, balancing dampers, attic code corrections, air cleaner installation, and full system commissioning.
- Removed the existing duct system in full.
- Installed new R-8 flex duct throughout the attic.
- Designed the duct system to room-by-room Manual D with CFM targets at every register.
- Added two new supply branches to the dining room and living room.
- Installed new takeoffs, flex runs, boots, and grilles with opposed blade dampers for the new supplies.
- Upsized the return as part of the duct replacement to support the new system’s airflow.
- Installed manual balancing dampers at every branch takeoff.
- Strapped all duct runs to current code requirements.
- Installed a Daikin One air cleaner in the return plenum.
- Built a code-compliant attic drain pan with float switch under the air handler.
- Enlarged the attic access opening to 20"x30", reframed the opening, patched drywall, and installed a new insulated hatch.
- Installed a new fused disconnect and liquidtight whip at the outdoor unit.
- Reused the existing refrigerant lineset where serviceable.
- Removed and disposed of all old equipment and ductwork.
- Performed room-by-room air balancing and commissioning to the design targets.
Daikin DH6 inverter heat pump, ECM air handler, and R-8 ductwork
The final system pairs a Daikin DH6 variable-speed inverter heat pump with a matched ECM air handler, whole-home air cleaner, new ductwork, and airflow corrections for previously underserved rooms.
Daikin DH6VSA4810A
4-ton variable-speed inverter heat pump using R-32 refrigerant.
Daikin DFVE48CP0300A
4-ton 115V variable-speed ECM air handler, R-32 compatible.
Daikin One air cleaner
Installed in the return plenum to support whole-home air filtration.
New R-8 flex duct system
Designed and balanced room by room, with manual balancing dampers and an upsized return trunk.
A variable-speed system only works properly when the ducts can move the air
A variable-speed inverter system is built to ramp up and down quietly while holding steady conditions across the home. That only works if the duct system can move the air the equipment is asking for.
Designing the ductwork to Manual D, upsizing the return, adding supplies to the two underserved rooms, and balancing room by room after startup is what separates a clean system design from a basic equipment swap. The attic corrections also improve safety and serviceability.
Before, during, and after the Alhambra Daikin DH6 installation
The photos below show the old outdoor condenser, removed equipment, attic duct replacement, new Daikin air handler, Manual D duct installation, and completed outdoor heat pump system.
Better airflow, cleaner filtration, and current-code attic work
This project replaced the equipment and the airflow system together, giving the home a modern Daikin variable-speed heat pump, new ECM air handler, new R-8 ductwork, return correction, added supplies, and room-by-room balancing.
Room-by-room airflow design
New ductwork was designed with Manual D targets, then balanced after startup so each room receives the airflow it was designed for.
Improved system support
Upsized return ductwork and new supply branches help the Daikin inverter system move air more effectively.
Code and serviceability updates
The attic received a code-compliant drain pan, float switch, improved access opening, new hatch, and properly strapped duct runs.
Planning a heat pump and ductwork upgrade?
Cold Cloud Mechanical designs heat pump installations around airflow, duct sizing, return capacity, equipment performance, filtration, code requirements, and long-term serviceability.