04 Equipment & Sizing

Central air

Central air is appropriate when ductwork already exists. For new installs without ducts, lead with mini splits instead — they give the homeowner sectional heating and cooling room by room.

Brands

Brand	Notes
Gree	Default
Mitsubishi	Available; same warranty caveats as mini split Mitsubishi

Warranties (central air)

Brand	Warranty
Gree	10 years
Mitsubishi	10 years (not 12 — that 12-year term is for mini splits only)

Ductwork policy

Sunny generally does not do ductwork. Try to stay away from selling jobs that require new duct runs.

Exceptions:

New builds where the homeowner is willing to pay for it — ductwork can be arranged

For everything else: lead with mini splits. They give sectional heating/cooling and avoid the ductwork problem entirely.

Sizing rules

Job type	Tonnage rule
Decommissioning	Default to 5 tons to cover full-home BTU for Con Edison
Non-decommissioning replacement	Stay at existing tonnage. A 3.5-ton replacement can become a 3-ton if appropriate

See Sizing rules for context.

Multi-fuel setups (gas heat + heat pump AC on same thermostat)

Some homeowners ask whether they can keep their gas boiler for heat and use a heat pump only for cooling, all controlled by the same thermostat.

Sunny does not do this setup. It is technically possible but we don’t dabble in it.

What we do support

If the homeowner already has separated thermostats for heating and cooling (their existing setup), they can:
- Use the new central air only for cooling
- Keep their existing heating thermostat untouched
One thermostat per unit is the standard

See Hybrid: keep gas + add heat pump for the broader scenario.

Situation	Recommendation
Existing ducts in good condition	Central air is fine
No existing ducts	Mini splits
Homeowner wants room-by-room control	Mini splits
Multi-family with isolated units	Mini splits (single-zone per unit often)
New build with budget for ducts	Either; mini splits still preferred