HVAC Systems: Rooftop, Residential, Mini-Splits & Commercial
Just what you need to know before you call a pro.
1. What all HVAC systems have in common
Every system moves heat out of your home in summer and in during winter.
| Component | What it does | Sign it’s failing |
|---|---|---|
| Evaporator (indoor) | Absorbs heat from room air | Vents blow warm air / ice on indoor pipes |
| Condenser (outdoor) | Dumps heat outside | Fan not spinning / loud buzzing |
| Compressor (inside outdoor unit) | Pumps refrigerant | Clicking + no cooling + outdoor unit runs briefly |
For interns: Anchor content to these three terms. They’re the most-searched diagnostic keywords.
2. Residential setup (what 90% of homes have)
Split system = outdoor condenser + indoor air handler (furnace or fan coil).
Where to find it: Big metal box outside (condenser). Basement/attic/closet indoors (air handler).
Common issue: Clogged filter freezes the indoor coil → “air blowing but not cold.”
Ductwork = metal or flex tubes that carry cold air to each room.
Leaky ducts = high summer bills but no single room is truly cold.
3. Mini-splits (ductless)
Best for: Additions, garages, sunrooms, or old homes without ducts.
Outdoor unit (1 compressor) connects to 1–4 indoor heads mounted high on walls.
No ducts = no filter-in-the-furnace confusion. Each head has its own washable filter.
Key homeowner tip:
If one head blows warm but others are cold → that head’s refrigerant valve failed (pro repair).
If all heads blow warm → outdoor unit problem.
For interns: “Mini-split” + “ductless” + “heat pump” overlap. Write “mini-split heat pump” for search volume.
4. Rooftop units (RTUs)
Common in: Mobile homes, some townhouses, commercial buildings. Rare in standard single-family homes.
Entire system (evaporator + condenser + compressor) sits on the roof.
Looks like a large metal box with a service panel.
Homeowner reality: You cannot DIY a rooftop unit. Access requires a ladder + safety gear.
For interns: RTU content targets commercial HVAC keywords, not residential. Use “rooftop HVAC” only if your client serves apartment complexes, commercial malls, and other commercial buildings.
5. Commercial HVAC (what you see on stores & offices)
Larger versions of residential systems but with key differences:
| Feature | Residential | Commercial |
|---|---|---|
| Location | Ground/attic | Roof (RTU) or mechanical room |
| Thermostats | 1 per home | 3–20 zones |
| Filter type | 1” disposable | 2–4” or electrostatic |
| Repair cost | 800 | 5k+ |
Why homeowners see this: You don’t own it, but if you run a business from home, your residential system won’t handle the load.
One decision tree for homeowners
My system is blowing but not cold →
Go outside: Is condenser fan not spinning? → Book a tech (capacitor/compressor)
Check indoor filter: Dirty? → Replace first, wait 2 hours
See ice on the thick copper line at indoor unit? → Turn off cooling, call a pro (leak)
For SEO interns: Terms to map to content
| Term | Points to this page section | Search intent |
|---|---|---|
| “split system HVAC” | Section 2 | Homeowner learning basics |
| “ductless mini split not cooling” | Section 3 | Troubleshooting one head |
| “rooftop HVAC unit” | Section 4 | Commercial or mobile home |
| “what is a condenser” | Section 1 (table) | Diagnostic search |
| “HVAC for small business” | Section 5 | Commercial transition |
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