A Historic Glendale Home, Planned in 3D Before Installation
Three levels, a small mechanical closet and a lot to connect. We worked the whole system out on paper and in a 3D model first, then built it to the model.
An undersized single-stage furnace and air conditioner replaced with a zoned Daikin VRV heat pump: one wall-mounted outdoor unit, three indoor units, Manual J and Manual D design, custom plenums and registers.
- Location
- Glendale, CA 91208
- Completed
- August 2025
- System
- Daikin VRV heat pump, 3 zones
- Outdoor unit
- Daikin RXTA60AAVJU, 5 ton
- Indoor units
- Daikin FXTA42, FXMA30, FXSA05
- Design
- Manual J, Manual D, 3D closet model
- Controls and air
- Daikin One Touch, Daikin One air cleaner
- Permit and testing
- City of Glendale permit, HERS verified
From the old closet to the finished system
A complex retrofit goes right when the thinking happens before the crew arrives. This project moved in four steps.
- 01
Before
An undersized single-stage system, worn ductwork with asbestos-containing sections and a small closet in a three-level historic house.
- 02
Plan
Room-by-room Manual J and Manual D, three zones on one Daikin VRV heat pump, and every placement reviewed on paper with the homeowner.
- 03
3D model
The closet modeled with the indoor units, plenums, transitions and service clearances. Two layouts compared, the second one built.
- 04
Result
Installed to the model: three quiet zones, custom plenums and registers, permitted, HERS verified and inspected.
What we started with
Some homes are easy to air-condition. This one was not. It is an older, historic home in the Glendale foothills with real architectural character. It sits on three levels, every room has a different shape, ceiling height and exposure, and none of the original construction was designed around modern HVAC. The walls have no insulation. Some of the old ductwork had asbestos-containing material. And the space set aside for mechanical equipment was a small closet.
The new owners had just bought the house and wanted it sorted out before they moved in. They first called us about old ducts that ran through the lower hallway and got in the way. When we looked closer, the ducts turned out to be the smaller part of the problem: one single-stage furnace and one air conditioner, undersized for the home, were trying to serve three levels with very different loads. Some rooms got too cold while others stayed hot.
Thinking it through before anything was built
Before we talked about equipment, we worked out the loads, the zones and where everything would go.
- 01
The math came first
A room-by-room Manual J load calculation covered the actual wall construction, window orientation, ceiling heights and the extra outside air an uninsulated historic house lets in. It came to roughly 60,000 BTU, spread very unevenly across the three levels. A rule-of-thumb sizing ("it's 2,000 square feet, so it needs 4 tons") would have been wrong here. A Manual D duct design then sized the supply and return for every room.
- 02
Zones, not dampers
One large system on dampers would have had almost no reserve on the hottest Glendale afternoons and could not have balanced the rooms well. Three separate condensers would have been bulky, hard to place and noisy for the neighbors. One Daikin VRV outdoor unit with three indoor units gave each zone its own control.
- 03
Reviewed with an architect
The homeowner is an architect and urban planner. He asked whether we could get rid of the furnace entirely, how big and how loud the outdoor equipment would be, whether each zone needed its own controls, and where the supply register should sit in the master bedroom so air moves through the room instead of straight out the door. Every placement decision was reviewed by both sides on paper before anything was built.
The closet, modeled in 3D
The mechanical closet was tight, and in an old house a few inches decide whether a layout works. Before ordering equipment, we modeled the closet in 3D with the new indoor units, plenums, transitions and service clearances in place, so we could see how everything would fit and connect.
We developed two layouts, reviewed them with the homeowner and chose the second one, because it gave the best airflow while leaving room for service access. The custom supply and return plenums were designed to fit the space and match the Manual D airflow targets.
How it looks now
The crew installed the closet to the 3D layout. The Daikin indoor units and the custom plenums sit where the model put them, with room left for service access. Returns were custom-built for each zone and painted black inside so the ductwork is not visible through the grilles.
Outside, a single wall-mounted Daikin VRV outdoor unit serves all three zones, in place of the old condenser.
One quiet outdoor unit, three zones
A Daikin VRV heat pump feeds refrigerant from one outdoor unit to three independent indoor units. Each zone heats and cools on its own schedule and its own thermostat.
Daikin RXTA60AAVJU
5-ton VRV heat pump on R-32 refrigerant, wall-mounted. One quiet outdoor unit feeds all three indoor units and handles both heating and cooling, so the furnace is gone.
Daikin FXSA05AAVJU
Compact slim-duct unit sized for the office only. It gives the room precise temperature control and takes the office load off the rest of the system.
Daikin FXTA42AAVJU
Multi-position ducted unit in the mechanical closet, with a custom-designed return placed so the open living area circulates evenly.
Daikin FXMA30AAVJU
2.5-ton concealed ducted unit in the attic above the bedrooms, with ducts designed so airflow stays quiet for the people sleeping nearby.
Every zone has its own Daikin One Touch thermostat and a Daikin One air cleaner with MERV 15 filtration.
What Cold Cloud Mechanical completed
From the load calculation to the final inspection, the whole project was designed, installed and documented by our team.
- Ran a room-by-room Manual J load calculation and a Manual D duct design for every room.
- Modeled the mechanical closet in 3D with the indoor units, plenums, transitions and service clearances, and built the second of two layouts reviewed with the homeowner.
- Removed the old furnace, the outdoor condenser and its wiring, and all accessible old ductwork, including the runs blocking the lower hallway.
- Removed the asbestos-containing duct sections under containment: plastic sheeting over every affected room, air filtration, wet methods, bagging and specialized disposal.
- Installed the Daikin VRV outdoor unit on a wall-mounted bracket with anti-vibration pads and a new disconnect, and replaced the breaker with a 35 A breaker.
- Ran a new insulated refrigerant line set (an 88 ft main run and a 16 ft branch) and trimmed the R-32 charge for the actual line length.
- Installed three indoor units: a slim-duct unit for the office, a multi-position ducted unit for the living areas and a concealed ducted unit in the attic for the bedrooms.
- Fabricated custom supply and return plenums and custom returns for each zone, painted black inside so the ductwork is not visible through the grilles.
- Built the new duct system to the Manual D design, sealed and insulated, and measured airflow at the registers after startup.
- Installed the custom architectural registers the owners chose from Pacific Register in brass, plaster and black steel.
- Installed a Daikin One Touch thermostat and a Daikin One air cleaner with MERV 15 filtration for each zone, plus a condensate pump with a sealed drain exit.
- Pulled the City of Glendale mechanical permit, completed the CF1R Title 24 documentation, had an independent HERS rater verify the system and passed the City final inspection.
Old ductwork out, new ductwork and registers in
All accessible old ductwork was removed, including the runs blocking the lower hallway. Some sections contained asbestos. We removed them under containment: plastic sheeting over every affected room, air filtration and wet methods to keep fibers out of the air. The material was bagged and sent for specialized disposal.
The new duct system follows the Manual D design: sealed, insulated and routed to keep the living spaces clear.
The owners chose the registers to match the home's character. They are custom architectural grilles from Pacific Register in brass, plaster and black steel. The floor registers are cut from heavier-gauge brass and steel, so they are rated for foot traffic. They look like they have always been part of the house.
The result
Today the house has three comfort zones that each work on their own, a quiet heat pump in place of the old furnace, cleaner air throughout, and ductwork and registers that suit the architecture. The system was sized from real calculations, laid out in 3D, built to the model and inspected by the city. That is how we approach every heat pump installation in Glendale, and it matters most in homes like this one.
- 01
Three zones, one quiet outdoor unit
The office, the living areas and the upstairs bedrooms each run on their own indoor unit and thermostat, fed by a single wall-mounted Daikin VRV outdoor unit.
- 02
Planned, then built
Room-by-room Manual J, Manual D ductwork and a 3D model of the closet meant the crew installed a layout that had already been checked, not one improvised on site.
- 03
Permitted, verified, inspected
City of Glendale mechanical permit, CF1R Title 24 documentation, independent HERS verification and a passed City final inspection.
Questions about planning a heat pump retrofit
Why model an HVAC installation in 3D?
In a tight space, a few inches decide whether the equipment, plenums and service clearances fit. A 3D model lets us and the homeowner check the layout before equipment is ordered, so the installation follows a plan instead of being improvised on site.
Can you install a heat pump in a historic home with no wall insulation?
Yes. The key is a proper Manual J load calculation that accounts for the higher air leakage of an older home, so the system is sized correctly.
What is a VRV system, and is it good for a house?
VRV (variable refrigerant volume) connects one outdoor heat pump to several indoor units, and each one runs as its own zone. It works well for multi-level homes with uneven loads and for owners who want one quiet outdoor unit instead of several.
Do I need a permit to replace my HVAC system in Glendale?
Yes. Replacing heating and cooling equipment in Glendale requires a mechanical permit, Title 24 compliance, HERS verification and a final city inspection. We handle all of it as part of our HVAC services in Glendale.
What are Manual J and Manual D?
Manual J calculates how much heating and cooling each room needs. Manual D designs the ductwork to deliver that airflow to each room. Together they prevent an oversized or undersized system and uneven, noisy airflow.
Planning HVAC for a complex or tight space?
We work the layout out before installation: a room-by-room load calculation, a duct design and, for tight spaces like this closet, a 3D layout. Then we build to the plan and handle the permit, Title 24 documentation, HERS verification and inspection.
Prefer to call? (747) 298-8580