# What a typical mini split installation looks like, start to finish (an illustrative walkthrough) > An illustrative walkthrough of a typical single-zone mini split installation in a San Diego house, from the first call to commissioning. Not a real job. URL: https://mesaminisplitsandiego.com/blog/what-a-mini-split-install-looks-like/ Illustrative Walkthrough An illustrative walkthrough, not a real job: one upstairs bedroom in a made-up mid-century San Diego house, followed from the first call to the final walkthrough so you can see what happens at each stage and why. > An illustrative walkthrough > > This post describes what a typical job looks like from start to finish. It is not the record of a specific completed project. > Illustrative walkthrough > > This is an illustrative walkthrough, not a real job. The house, the room and every finding below are invented to show how a typical single-zone installation runs. Nothing here describes a specific customer or project. A typical mini split installation runs through a first call, a site visit with a load calculation, a written scope, a permit, the installation and testing, an inspection and a walkthrough. This post follows one invented project through each stage. [Mesa Mini Split San Diego](https://mesaminisplitsandiego.com/) installs mini splits across San Diego County, with the work done by licensed and insured contractors holding the California C-20 (HVAC) license. The [installation process guide](https://mesaminisplitsandiego.com/guide/mini-split-installation-process/) explains each step in technical detail; this walkthrough shows how they fit together on one house. ## The house and the problem Imagine a two-story stucco house from the 1960s in an inland part of the City of San Diego, with a wall furnace downstairs and no ducts. The upstairs main bedroom faces west, has two windows and sits under the roof. On summer evenings it stays well above the rest of the house, and the owners sleep downstairs during heat spells. They want that one room fixed. ## The first call and the site visit On the first call the owners describe the room and the house. At the site visit the room is measured, including its windows and their orientation, and the attic insulation is checked. A Manual J load calculation sets the head’s capacity. The visit also looks at the panel (a 100-amp service, in this example, with two open spaces) and walks the outside of the house to find a spot for the outdoor unit. The side yard below the bedroom is narrow. The outdoor unit goes on the opposite side, where the yard is wider and the unit can sit more than 4 feet from the property line, as the City requires for at-grade units in required side yards without sound attenuation. That adds line-set length, so the route is measured against the model’s published limits. The [placement guide](https://mesaminisplitsandiego.com/guide/mini-split-placement/) explains the trade-off. ## The written scope The scope names the indoor and outdoor model numbers, the head location above the bedroom door, the line-set route through the exterior wall and down a painted line-hide, a gravity condensate drain running inside the line-hide to a splash block, a new dedicated 240V circuit with a disconnect beside the outdoor unit, the City permit and the commissioning steps. A single-zone job of this kind falls within the typical San Diego-area range of about $3,000 to $7,500; the [installation cost guide](https://mesaminisplitsandiego.com/guide/mini-split-installation-cost-san-diego/) explains what moves a job within it. ## The permit The house is not historically designated, so in the City this is a no-plan combination permit covering the mechanical and electrical work, starting from $176.57 for the first mini-split unit. The contractors pull it and coordinate the inspection. ## Installation day The head’s mounting plate goes up first, level and anchored to framing. A core drill makes one penetration through the stucco, angled slightly to the outside. The line set, communication cable and drain pass through it, the opening is sealed, and the stucco is patched. Outside, the outdoor unit is set level on a pad with rubber isolation feet, the line-hide goes up the wall, and the new circuit runs from the panel to the disconnect. The [electrical requirements guide](https://mesaminisplitsandiego.com/guide/mini-split-electrical-requirements/) covers the circuit. ## Testing and commissioning The flare connections are tightened to the specified torque. The line set and indoor coil are pressurized with dry nitrogen and held to confirm they are tight, then evacuated with a vacuum pump until a micron gauge shows a deep vacuum that holds. Refrigerant is released and the charge set to the manufacturer’s specifications, with extra added by weight for the longer run. The system runs in cooling and heating, and water poured into the drain pan runs out at the splash block, as the [condensate drainage guide](https://mesaminisplitsandiego.com/guide/mini-split-condensate-drainage/) describes. ## Inspection and walkthrough The City inspector checks the work against the permit, and any field verification on the compliance form is completed. At the walkthrough the owners learn the remote, the quiet mode, how to clean the filters and why cooling before 4 p.m. matters on SDG&E’s time-of-use rates. If your project looks like this one, or nothing like it, the [cost estimator](https://mesaminisplitsandiego.com/tools/mini-split-cost-estimator/) gives a planning range, and a call or estimate request books the site visit for your own house. ## Questions about this post ### Is this walkthrough based on a real installation? No. It is an illustrative composite that shows how a typical single-zone job runs, built from the steps the contractors follow. The house, the room and the findings are made up. Real jobs differ in the number of heads, the routes, the electrical work and the permit path, which is why every quote starts with a site visit. ### What should a homeowner prepare before installation day? Clear access to the wall where the head will go, the electrical panel and the outdoor location, and move furniture and fragile items away from the work area. Keep pets in another room, since doors will be open and tools will be out. If an HOA or a neighbor needs notice for access along a shared side yard, arrange it ahead of time. ### What paperwork should I have once the installation is finished? Keep the written scope, the equipment model and serial numbers, the owner's manuals, the finaled permit and any field verification documents the compliance form required. Those records help with future maintenance, repairs and resale, and they show which refrigerant and line set the system uses if it is ever replaced. Want this answered for your house? Call with the rooms you want cooled and your ZIP code. ## Keep reading - Learn [How long does it take to install a mini split?](https://mesaminisplitsandiego.com/guide/mini-split-installation-process/)There is no honest single number. What sets the timeline is the scope: how many heads, how far the lines travel, whether the panel needs work and how the permit and inspections fall. Here is the sequence and what stretches each part of it. - Decision Guide [Mini split outdoor unit placement: where should it go?](https://mesaminisplitsandiego.com/guide/mini-split-placement/)The outdoor unit's location sets the line-set route, the noise a neighbor hears, how long the coil lasts near the coast and which permit path applies. Here is how to choose it, and where the indoor head should go once it is chosen. - Learn [How does a mini split condensate drain line work?](https://mesaminisplitsandiego.com/guide/mini-split-condensate-drainage/)Every indoor head makes water when it cools, and humid coastal San Diego makes plenty. Where that water goes, by gravity or by pump, decides whether a mini split stays dry for years or drips down a wall. - Learn [What are the electrical requirements for a mini split?](https://mesaminisplitsandiego.com/guide/mini-split-electrical-requirements/)How the circuit, breaker and wire for a mini split are chosen from the equipment's own nameplate, why the outdoor unit gets a disconnect beside it, and how to tell whether an older San Diego panel has room or needs a service upgrade. - Cost Guide [How much does mini split installation cost in San Diego?](https://mesaminisplitsandiego.com/guide/mini-split-installation-cost-san-diego/)Typical San Diego-area ranges by number of indoor heads, the published permit fees, the parts of a price that only a site visit can settle, and an honest look at rebates and running costs.