TL;DR
Get backup power and energy gear delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
A builder planning a small North Texas granny flat says they are leaning toward four single-zone mini-splits instead of a central ducted HVAC system. Their reasons include room-by-room temperature control, possible duct losses and redundancy, but the post describes a proposal and personal reasoning, not measured performance or a completed installation.
A builder planning a 1,120-square-foot granny flat in North Texas says they are more persuaded by a system of four single-zone mini-splits than by a central ducted HVAC unit, reopening a practical design debate for small, high-performance homes. The GreenBuildingAdvisor post describes the builder’s plan and concerns, but does not report a final installation or performance results.
The proposed home has two bedrooms and an 800-square-foot conditioned attic. The poster estimates its heating load at about 21,000 Btu on the coldest design day. Their contemplated layout assigns one mini-split to each bedroom, one to the living room and kitchen, and one to the attic. They say they are considering four 9,000-Btu units, which they estimate could be bought and installed for about $500 each. The post also says 6,000-Btu models are available, with prices starting at $1,400, but does not clarify whether those figures use the same installation and cost assumptions.
The poster says other people in a separate group favored a central system. In response, they question whether ducted equipment would offer meaningful advantages in this particular house. They argue that separate indoor units could let occupants cool a bedroom at night without cooling the whole home, and that multiple units could provide some conditioning if one unit failed.
Other concerns raised include duct heat loss or gain, cleaning ducts over time, and how a single thermostat would respond to the home’s planned south-facing living area and north-side bedrooms. The poster expects passive solar gain through the living-room windows could leave that space warm while bedrooms remain cold. They also say they plan to use an ERV—an energy recovery ventilator—for ventilation and air filtration, rather than relying on the HVAC system alone.
Room-by-Room Control Versus Central HVAC
The debate matters to homeowners because equipment choice affects more than the heating and cooling load. Room-by-room control can suit occupants with different schedules or temperature preferences, while a central system can distribute conditioned air through a shared duct network. Whether either approach works well depends on the building layout, equipment sizing, climate, controls and installation quality.
The poster’s reasoning also highlights trade-offs rather than settling them. A ductless setup may avoid long supply and return ducts, but multiple indoor units bring their own equipment, controls and maintenance needs. A central system may offer different filtration or humidity-management options, but those benefits depend on the specific design. The post does not include a modeled comparison, bids from contractors or operating data, so its cost and performance points remain the builder’s expectations rather than verified outcomes.
For a small, efficient home, load matching and distribution are especially relevant: equipment that is too large or poorly controlled may not behave as intended. The post raises questions for a design review, but does not establish that ducted systems are generally unsuitable or that four mini-splits will perform better in this house.
A Small Home With Separate Zones
The source is a first-person question posted to GreenBuildingAdvisor about a home still being planned. The poster describes a small residential project with distinct spaces, including an attic intended to be conditioned. Their interest in separate indoor units follows from that layout and from the difference they anticipate between sunny common areas and cooler north-facing bedrooms.
The post also refers to arguments made by others in another group: that a central unit would be better, could control humidity, might avoid short cycling and could provide stronger filtration. The poster challenges those points, including by asking why some high-performance homes in the same climate zone use whole-house dehumidifiers alongside central HVAC. No specific homes, system specifications or measured humidity data are named, so that observation cannot establish how common the practice is or why each system was selected.
In the proposed design, an ERV would provide ventilation at a stated target of 0.35 air changes per hour and would be used for filtration. The source does not provide a ventilation calculation, filter specification or detailed HVAC design. Those details would be needed to assess how the proposed system would meet the home’s ventilation, comfort and air-quality requirements.
“I’m more convinced than ever that DUCTED hvac is not the way.”
— The builder, in a GreenBuildingAdvisor post
Performance and Cost Remain Untested
The source does not say whether the builder has selected equipment, received contractor bids or installed any of the proposed units. The $500 and $1,400 figures are presented without a detailed breakdown, and it is unclear whether they cover comparable equipment, installation scope, controls, electrical work or other project costs.
It is also unclear how the four units would be sized and controlled, whether each could operate efficiently at the home’s actual loads, or how the attic would be served. The post does not include cooling-load estimates, humidity measurements, equipment specifications, duct-design comparisons or filtration test data. The claim that one or two units could condition the whole house is the poster’s expectation, not a demonstrated result.
No independent expert response or final decision appears in the provided material. The concerns about duct cleanliness, filtration, humidity and redundancy are therefore points raised for discussion; they are not confirmed defects in the proposed central-system alternative.
Design Decisions Before Installation
The next step is for the builder to settle the system design with project-specific load calculations and equipment details. A meaningful comparison would account for installed costs, ventilation and filtration plans, humidity control, room-by-room loads, sound, controls and maintenance. The source does not state when that work or construction will be completed.
Until the system is installed and monitored, there is no reported evidence about comfort, energy use or whether the proposed units can meet the home’s needs. Any later update would need to distinguish the original estimate and expectations from measured results.
Key Questions
Has the builder installed the four mini-splits?
The source does not say. It describes a planned system for a granny flat that is being built, not a completed installation.
What is the proposed layout?
The poster is considering four single-zone units: one for each of the two bedrooms, one for the living room and kitchen, and one for the conditioned attic.
Why does the poster prefer separate units?
They point to room-by-room temperature control, concerns about duct losses and cleaning, possible thermostat problems with passive solar gain, and backup capacity if one unit fails. These are the builder’s arguments, not verified findings about the proposed system.
Does the post show that ductless HVAC is cheaper or more efficient?
No. The post gives equipment-price figures but does not provide a comparable installed-cost estimate, energy model or measured operating data. It does not establish which option would be cheaper or more efficient for this home.
Source: rss
Halloween Picks
halloween
As an affiliate, we earn on qualifying purchases.
