- Home
- Adding cooling
Three ways to cool a building that never had air conditioning.
Most older homes and plenty of small businesses around the bay were built without cooling. There are three sensible ways to add it. Which one fits depends mostly on one question: are there ducts?
Five questions, three routes.
| Question | Use the ducts you haveHeat pump or AC on existing furnace ducts | DuctlessWall or ceiling heads per room | Small-ductHigh-velocity flexible tubes |
|---|---|---|---|
| Needs existing ducts? | Yes — and they must be sized and sealed well enough. | No ducts needed at all. | No — it brings its own small tubes. |
| Disruption to the building | Low, if the ducts are usable. | Low — a small hole per head for the line set. | Moderate — tubes run through closets, attics and walls. |
| Whole-building coverage | Whole house, through every existing vent. | Room by room — only rooms with a head. | Whole house, through small round outlets. |
| What you see indoors | Nothing new — the existing vents. | A visible head on the wall or ceiling of each room. | Small round outlets, a few inches across. |
| Heats as well as cools? | Yes, if it's a heat pump; the furnace can stay as backup. | Yes — ductless systems are heat pumps. | Yes, with a heat pump or a hot-water coil; depends on the system. |
A general comparison. Costs, electrical upgrades and permits depend on the building, so we don't publish them here — the estimate visit covers them.
If you have a furnace with ducts, start there.
Many houses heated by a gas furnace already have ducts to every room. A heat pump or air conditioner can often use them. The question is whether the ducts are big enough and tight enough for cooling, which needs more airflow than heating. We measure before we promise.
No ducts? Ductless is the usual answer.
An outdoor unit feeds one or more indoor heads through a small line set. Each room with a head gets its own temperature control. It's the simplest way to cool a bedroom, an office or a shop that never had ducts.
Want every room, without the heads? Small-duct.
High-velocity systems push air through narrow flexible tubes that can be threaded through closets and walls with little demolition — often the choice for older houses where people don't want wall units.
The electrical panel matters
Adding cooling adds electrical load. Older panels sometimes need an upgrade first; we check on the estimate visit and tell you plainly, so there are no surprises later.
Most common here
Ducts from an existing furnace in post-war houses; ductless or small-duct in older ones.
Shops and offices
Ductless for single rooms and studios; rooftop or split systems for whole suites.
We'll look and tell you.
Ducts, panel, rooms — one visit, a straight recommendation.