04 Equipment & Sizing

Mini splits — sizes & zones

Mini splits are Sunny’s preferred equipment for residential heating and cooling because they allow sectional control room-by-room.

Available sizes

Why 7K is being phased out

7K isn’t just temporarily out of stock — Sunny is deliberately moving away from it. Two reasons:

Issue	Why it matters
7K is single-zone only	It cannot be connected to a multi-zone condenser. If you sized a multi-zone system around 7K heads, you’d need extra condensers — more equipment, more piping, more time.
Only $100–$200 cheaper than 9K	The cost savings are tiny compared to the operational complexity it adds.

The math doesn’t favor 7K in nearly any real install. Default to 9K for any small bedroom, and reach for 12K only when the room is genuinely a master/suite. See Sizing rules for the full default-size table.

Five residential sizes:

Size	Status	Notes
7K	🚫 Out of stock until further notice	Multi-zone head only when available; upsize to 9K for now
9K	✅ Available	Smallest currently available size; smallest single-zone option
12K	✅ Available	Most common for standard rooms
18K	✅ Available	Larger rooms
24K	✅ Available	Open-concept living/dining/kitchen

A 30K option exists but it’s commercial-grade. We don’t typically use it in homes.

Single zone vs multi-zone

Single zone

One condenser outside, one head unit inside. Available in 9K, 12K, 18K, 24K. (There’s no 7K single-zone, and even when 7K returns to stock it’s multi-zone-head only.)

Multi-zone

One condenser outside serving multiple head units inside.

Multi-zone units cannot do heating and cooling simultaneously across zones. Every head unit on the same condenser must be in the same mode at the same time.

This is why room assignment matters when planning multi-zones.

Assigning rooms to condensers

Ask the homeowner who sleeps where. The general pattern:

Older occupants usually want heat more often
Younger occupants usually want AC more often

Group rooms with compatible needs on the same condenser. If grandma’s bedroom and a teenager’s bedroom share a condenser, one of them will be uncomfortable most of the time.

Sizing each room

See Sizing rules for the full guidance. Quick version:

Square footage × 20 = BTU needed (rule of thumb)
Small rooms: 9K or 12K
When in doubt between 9K and 12K, always go 12K (winter safety)
Open-concept living/dining/kitchen: prefer two units; 24K can cover one large open area

Brand selection

Default to Gree. See Brand selection for when Midea or Mitsubishi makes sense.

Comfort, insulation, and usage questions

Mini splits are not just a bill-reduction product. They give the homeowner room-by-room comfort, schedules, and better control than one boiler serving the whole house.

If the homeowner asks whether poor insulation will make the system ineffective, keep the comparison fair: poor insulation hurts their current boiler too. Better insulation always helps, but it is not a unique weakness of mini splits, and Sunny does not sell insulation work as an adder.

If the homeowner asks how much their electric bill will increase, do not invent an average. Usage drives the answer: setpoints, schedules, how many units they leave running, and whether they use the app/remote correctly. The install team walks them through scheduling and efficient operation before leaving.

If they previously had mini splits that did not heat or cool well, ask what brand, size, and install quality they had. Bad brand selection, poor install work, or undersized equipment are different from a properly designed Sunny install.

Electrical impact

More units = more amperage. See Electrical & sub-panel — sub-panels are often required.