AC installation and replacement in San Mateo County
Replacing your AC? Here's the plan.
A new central AC is sized to your house, installed with the ducts sealed and tested, and set up with an upgraded thermostat. A few Peninsula cities now ask for a heat pump instead of a new AC, so the first job is finding out which rule applies to you.
What an AC replacement covers
A new AC is more than swapping a box outside. The unit, the indoor coil, the refrigerant lines, the ducts and the thermostat all have to work together, and the state now has a say in several of those.
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We look at the house, not just the old unit
Sizing starts with the house: its rooms, windows, insulation and which way it faces. Copying the tonnage of the old unit is how a system ends up too big, cycling on and off and never drying the air properly.
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We set the new equipment
The outdoor unit goes on a level pad, the indoor coil or air handler goes in, and the refrigerant lines, power and condensate drain are connected and checked.
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The ducts get sealed and tested
The Energy Code ties a replacement to the ducts that carry the air. They must be sealed by the installer and checked by an independent rater.
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Thermostat, refrigerant and start-up
A refrigerant-containing part going in means a digital setback thermostat goes in too. Then we run the system through a full cycle and check the readings before we leave.
Do I need a permit to replace my air conditioner?
Plan on it. Replacing an AC outdoor unit is regulated mechanical work, and since January 2026 the new California Energy Code has covered alterations to existing homes, so a replacement is held to it.
The permit steps themselves are set by your city's building department, and they differ from city to city. Our permit guide sets out what each city we work in asks for.
Source: California Energy Commission news release, checked 2026-10-17
Does replacing only the outdoor unit still need a duct test?
Yes. The state's own compliance manual answers this exact question: replacing the outdoor unit by itself, or the indoor unit by itself, triggers duct sealing and verification.
That surprises people who expect a like-for-like swap to be simple. If your ducts leak, the cost of fixing them lands on the same visit. It is also a good time to look at the duct system as a whole.
Source: California Energy Commission, 2025 Single-Family Residential Compliance Manual (June 2025), checked 2026-10-17
Where do I have to install a heat pump instead of an AC?
In Menlo Park, Portola Valley, Mountain View and Los Gatos, replacing an AC condenser can now mean installing a heat pump instead, which cools like an AC and also heats. Each city's own rule is below, from its own page.
Elsewhere a like-for-like AC may still be an option. Ask before you buy, because the rule that applies is the one for your address.
Tell us about the system you have now
Call and tell us the address and what's failing, or book a visit online.
Tell us what it's doing. We'll take it from there.
Call and describe the problem: the noise, the smell, the room that never warms up. Or book a visit online.
