The ambitious end of DIY: one precharged condenser feeding two to four indoor heads, which means routing multiple linesets through walls and joists on a weekend schedule. MRCOOL's DIY multi-zone kits make a whole-small-house retrofit possible without a contractor. Go in clear-eyed, though: every multi-zone tradeoff below applies here too (one compressor for the whole house, short-cycling when a single small zone calls), the lineset routing is 3x the work of a single, and if the condenser dies in February every room goes cold at once. Two DIY singles are often the smarter version of this project.
The catalog has 6 DIY multi-zone systems from 1 brand, priced from ~$3,104 to ~$6,631. 3 are rated to keep heating down to -13°F, the least expensive being the MRCOOL DIY 5th Gen Multi-Zone 18,000 BTU (2 x 9k).
Series photoMRCOOL · Multi-Zone DIY
~$3,104
Two small rooms, such as two bedrooms, on one 230V circuit and one outdoor unit, installed by the owner.
Series photoMRCOOL · Multi-Zone DIY
~$3,971
Two rooms now, with a third or fourth possible later, where yard space or panel capacity allows only one condenser and one circuit.
MRCOOL · Multi-Zone DIY
~$6,631
A whole-house owner install with four to six rooms where cold-weather heat output matters.
MRCOOL · Multi-Zone DIY
~$5,063
Zoning three rooms you'll install yourself, in a house cold enough that certified 5°F output matters more than the lowest kit price.
Series photoDiscontinuedMRCOOL · Multi-Zone DIY
~$3,500
Two-room setups — master plus living area — where yard space or panel capacity only allows one condenser and one circuit.
Series photoDiscontinuedMRCOOL · Multi-Zone DIY
~$4,600
Zoning three bedrooms or a whole ranch-house level without ductwork or a pro install budget.