How far should an AC condenser be from the house?

A central AC condenser can sit 6 to 12 in (15 to 30 cm) from the house, and a mini split outdoor unit 4 in (100 mm). Those are the makers' figures, from six installation manuals. But they are the gap at the back only. The side with the valves and the control box needs 18 to 30 in (46 to 76 cm). Anything above a central condenser should be 48 to 60 in (1.22 to 1.52 m) over its top. The building code sets no gap from the wall at all. It asks for a working space at the control side and sends you to the manual for the rest. The rest of the yard is in outdoor room dimensions.

What a condenser is, and why each side gets its own number#

Most home air conditioning is a split system. One part sits indoors and cools the air, and the other sits outside and throws the heat away. That outdoor part is the condenser, or condensing unit: a box holding the compressor, a large coil and a fan. A mini split is a split system without ducts, and its outdoor unit is a flatter box with the fan in its front face.

The two kinds move air in different ways, and that sets the clearances.

• A central condenser draws air in through the coil on its sides and blows it straight up out of the fan on top. Lennox's slab drawing marks the top as "discharge air".
• A mini split outdoor unit draws air in at the back and one side and blows it out of the front. Mitsubishi's base drawing labels the back and left side "air inlet" and the front "air outlet".

A clearance is the free space a maker asks for between its cabinet and anything solid: a wall, a fence, a shrub or another unit. Every figure here is measured from the outside of the cabinet. The service side is where the technician works. On a central condenser it is the corner with the control box and the refrigerant valves. On a mini split it is the side where the pipes connect.

So there is no single "distance from the house". Each face of the unit has its own number, and the manuals give the smallest one to the back.

Six manuals: 4 to 10 in at the back, 10 to 30 in at the service side#

These are the figures as each manual prints them. Several only draw them, so they are read here from the drawings.

Three things stand out.

Only one side gets the small figure. Carrier's words are "a 6-in. (152.4 mm) clearance on 1 side of unit and 12-in. (304.8 mm) on all remaining sides". Lennox is stricter, allowing 6 in on "the final side", 12 in on one other, 36 in on another, and 30 in "on one of the sides adjacent to the control box". So a Lennox unit can have walls close on two sides, at 6 in and 12 in, but never on three.

The mini split's front is the side that matters. Mitsubishi marks the front and top "clear", with two notes: the front can drop to 20 in (500 mm) "when any 2 sides of left, right and rear of unit are clear", and the top to 20 in "when front and sides of unit are clear". Fujitsu draws 24 in (600 mm) in front wherever a wall faces the fan. Daikin asks more than 350 mm (13 3/4 in) to a wall at the outlet, and that wall may be no taller than 1,200 mm (47 1/4 in).

Goodman says what the numbers are for. Its figures "meet requirements for air circulation only. Consult all appropriate regulatory codes prior to determining final clearances." It also says "corner installations are strongly discouraged". Fujitsu warns that less space than it shows "could cause a short circuit", meaning the unit pulls its own hot exhaust back in, and Mitsubishi says the efficiency of power usage "may fall about 10%" where poor ventilation causes it.

Where "2 feet from the house" comes from#

The figure most often repeated is 24 in, and it is in the manuals, but it is not the gap to the house. In Carrier's manual, 24 in (610 mm) is the service end and the gap between two units. In Lennox's, 24 in is also the gap between two units. Lennox's service side is 30 in (762 mm), not 24 in, which is a figure some summaries of that manual get wrong.

So both answers are in print. The smaller one, 6 to 12 in, is the back of the unit against the wall, and the larger one, 18 to 30 in, is the side a technician kneels at.

The building code: no wall gap, a 30 x 30 in working space#

The International Residential Code (IRC) does not say how far a condenser must be from the house. First, it hands the job to the maker. M1401.1 says heating and cooling equipment "shall be installed in accordance with the manufacturer's instructions and the requirements of this code". So the clearances in the manual become what the inspector checks.

Second, it asks for room to work. M1305.1 says appliances must be reachable "without removing permanent construction, other appliances, or any other piping or ducts". It adds: "A level working space not less than 30 inches deep and 30 inches wide (762 mm by 762 mm) shall be provided in front of the control side to service an appliance." That is the IRC's one figure for an outdoor unit, and it sits on the control side, not the back.

Third, it has a rule for the base. M1305.1.3.1 says equipment "supported from the ground shall be level and firmly supported on a concrete slab or other approved material extending not less than 3 inches (76 mm) above the adjoining ground." In the 2021 text that rule sits under the heading "Appliances Under Floors". The manuals ask for a firm, level base in the open yard anyway. Goodman wants "a solid, level foundation that will not shift or settle". Lennox allows its slab to slope at most 2 in per 5 ft (50 mm per 1.5 m), away from the house. Fujitsu, in snowy areas, wants a stand "at or above the anticipated snow depth".

Goodman adds one more point about the pad. To cut sound carried into the house, "the foundation slab should not be in contact with or be an integral part of the building foundation."

Worked through: one side yard 48 in wide#

Take a side yard 48 in (122 cm) wide, from the house wall to a fence. Walk a central condenser and then a mini split through it.

The condenser. Suppose it is a Lennox ML14XC1-036. Its manual gives the cabinet as 28 1/4 in (718 mm) across and 33 1/4 in (845 mm) tall. Suppose it is square in plan.

1. The back. Set it 6 in (152 mm) from the house, the "final side" Lennox allows at 6 in.
2. The fence side. The front face then sits 6 + 28 1/4 = 34 1/4 in from the wall. That leaves 48 - 34 1/4 = 13 3/4 in (349 mm) to the fence. Lennox needs 12 in on one side, so this passes by 1 3/4 in.
3. The two ends. They run along the yard, so they can take the 30 in (762 mm) and the 36 in (914 mm), and the IRC's 30 x 30 in fits in the first. The control box has to face one of the ends. If it faces the fence, the 30 in cannot fit and the plan fails.

So along the wall the unit claims 30 + 28 1/4 + 36 = 94 1/4 in (2.39 m).

The mini split. Now swap in a Mitsubishi MUZ-GS24. Its base drawing gives the body as 33 1/16 in (840 mm) wide and 13 in (330 mm) deep.

1. The back. 4 in (100 mm) from the house wall.
2. The front. It sits 4 + 13 = 17 in from the wall, which leaves 31 in (79 cm) to the fence. Mitsubishi asks 20 in (500 mm) when two of the left, right and rear are clear, and here the left and right are open, so this passes.
3. The ends. 4 in (100 mm) at the left and 14 in (350 mm) at the valve side, on the right.

Along the wall that is 4 + 33 1/16 + 14 = about 51 in (1.30 m).

Above the unit: 48 to 60 in, and why a deck is the usual problem#

A central condenser blows its hot air straight up, so the space above it matters as much as the space beside it. Carrier and Lennox both ask 48 in (1,219 mm) "above unit". Goodman asks for the top to be "completely unobstructed" where possible. Where something must be overhead, it wants "a minimum of 60 inches between the top of the unit and the obstruction(s)".

That is a real height. Take the Lennox ML14XC1-036 at 33 1/4 in (845 mm) tall: with 48 in on top, the lowest thing above must be 81 1/4 in (2.06 m) over the pad. A deck with its joists 7 ft (2.13 m) up passes, and one at 6 ft (1.83 m) does not. The joist and beam depths that set that height are in deck sizes and railing heights.

Mini splits blow sideways, so their top figures are smaller. Fujitsu draws a roof 24 in (600 mm) or more above the unit, with the front left open, and Daikin asks 300 mm (11 13/16 in) of work space below a ceiling.

Eaves bring a second rule. Carrier says to place the unit "so water, snow, or ice from roof or eaves cannot fall directly on unit". A unit tucked under a gutterless roof edge can meet every clearance and still fail that one.

Two units side by side: 10 to 24 in#

A house with two systems needs a gap between the outdoor units as well.

Where two different makes sit side by side, use the larger of the two figures. That is the site's rule, since neither manual covers the other unit. Mitsubishi adds one case: never set a unit where it takes in the "outlet air discharged by other units directly". So two mini splits should not face each other across a narrow gap.

Where these figures stop applying#

The figures here are for the six models named, from the manuals linked. Other models print other figures, so read your own. The IRC text is the 2021 edition as Colorado adopted it. Your state or city may adopt another edition or add rules of its own, which this page does not cover. Where your inspector or installer asks for more than a manual does, that governs.

This page is about airflow and service space. It does not cover the electrical disconnect, the refrigerant line run, rooftop units or units on wall brackets.

Other things near the unit keep their own rules. A propane cylinder's relief valve stays 5 ft (1.5 m) from exterior sources of ignition, and the fire code does not say whether a condenser counts as one, so ask your gas supplier; the rules are in how far a propane tank has to be from the house. A standby generator sets its own gaps to the wall and to openings, in how far a generator should be from the house. Lennox asks that exhaust from dryers, water heaters and furnaces be "directed away from the outdoor unit", because condensation from it on the steel cabinet will "diminish unit performance and longevity". Dryer vent terminals are placed in dryer venting dimensions and clearances.

Noise has no figure in any manual read here. Carrier says to keep the unit away from "windows, patios, decks, etc." where its sound may disturb people, Lennox prints "Install unit away from windows", and Daikin says to avoid places "near bedrooms". So plan the unit before the seating in patio sizes and layouts, not after. Metric figures are the manuals' own where they print them, and conversions otherwise, as imperial and metric dimension systems explains; check your own with the unit converter. Terms such as clearance are defined with others in the glossary, and the codes this site uses are listed under standards and codes.