Clearance distances for outdoor HVAC compressor/condenser units:
This article describes the recommended minimum (and maximum) distances to separate an air conditioner or heat pump outdoor compressor/condenser unit from building walls, other equipment, fences, shrubs, etc. In our photo at page top these two compressor/condenser units are too close together as well as too close to the building walls.
Green links show where you are. © Copyright 2015 InspectApedia.com, All Rights Reserved.
Blocking air flow through the outdoor A/C or heat pump compressor/condenser unit is a really bad idea that shortens equipment life (as the equipment runs hotter) and increases system operating costs (for the same reason - hotter operating temperature means lower efficiency during the cooling season).
Air conditioning or heat pump compressor/condenser units mounted too close to a wall, surrounded by shrubs, or multiple units located too closely together will probably not receive enough cool air flow to function properly.
And even worse, compressor/condenser units that are too close together not only have to fight for their incoming cooling air, but they may feed hot exhaust air to one another, increasing their operating temperatures still further.
The final authority on proper HVAC equipment clearance distances is the manufacturer's installation instruction manual. But here are some general rules of thumb for air conditioner or heat pump clearances that we will cite here.
[Click to enlarge any image]
In our photo at left the A./C compressor units are too close together and also suffer from airflow blocked by shrubbery. This collection of air conditioning compressors are too many too close together - they will be fighting for cooling air around the condenser unit, increasing operating cost and shortening air conditioner compressor life
A rule of thumb is to maintain at least two-feet (24") between the A./C compressor/condenser unit and any nearby obstruction such as a building wall, shrub, or fence.
If there are multiple air conditioner or heat pumps installed in the same area, and following the sense of the rule above, I'd keep the units at least 4 ft. apart from one another as well.
In our photo (left) from a home in New York, the compressor/condenser unit actually leaning against the house wall (its support pad tipped). About 1/3 of the air flow from this unit is completely blocked by the building wall.
At least the wall kept the unit from tipping over, though.
If you do not have manufacturer's installation instructions at hand we recommend following the "rules of thumb" for A/C or heat pump clearance distances given above.
But of course the final authority is the equipment manufacturer. Here is an adapted (reformatted) quote of clearance requirements from a Carrier 24ANA Infinity Series Air Conditioner of 2-5 nominal ton size A/C equipment installation manual:
Lennox® typical compressor condenser installation instructions (see REFERENCES) include these additional bits of advice about the outdoor condensing coil and compressor unit:
(Feb 19, 2015) Chuck said:
Are there any clearance requirements for condensing units and entrances?
You mean beyond what's in the article above and specific to building entries?
I haven't seen that explicit spec. beyond what's mentioned in the article above or a generic 3-foot rule to give good air circulation. Perhaps in the unit's installation guide you'll see some schematic on clearances that's different. Is this a noise complaint or an air flow concern?
In my opinion and probably the opinion of your local fire or building code compliance officials, the compressor/condenser should not be located where it forms an obstruction or hazard around building entrances. Since an exit stair or door wants at least a 3-foot landing or clearance in the direction of travel it seems to me that'd be a bare minimum and 48" or more makes more sense; imagine trying to bring a couch into a building having to lift it over the AC unit.
(Aug 4, 2015) Robert Mendez said:
Clearance space above an air conditioner compressor/condenser unit
Allow at least 48 in. (1219.2mm) above the compressor/condenser unit.
My question: what about the distance from the wall stretching out above the unit and to the sides? Any recommendation on the length? My e-mail is firstname.lastname@example.org
If you're talking about privacy walls or screens at patios or decks, say at a condo, the A/C compressor condenser side-clearance distances specified by the manufacturer (and cited above) need to be respected.
In our photo at left, from a Minneapolis MN home, these two compressor/condenser units are just about three feet apart - a little close, and that right-most larger compressor/condenser unit is too close to building walls, a clothes dryer vent, and shrubbery.
We also see that direct-vented heating appliance white PVC piping is blowing exhaust close to these units. The installation is nice-looking and neat though.
These four air conditioner compressors were found jammed into a wall niche along a street in Queretero, Mexico.
These units may have a short life before needing replacement.
Where there simply is not adequate space to provide proper air circulation around an air conditioning compressor or multiple compressors, it may be a good idea to let the building owner know that the units won't have a long life.
(Oct 19, 2015) Gary said:
Is there a specific clearance for an exterior downdraft kitchen vent on the exterior wall to the condensing unit ?
OPINION: While we can't anticipate every crazy installation of stuff on or around buildings (people are very creative), there are possible hazards that I can imagine, so I'd like to see 48", principally because I don't want kitchen grease accumulating on the top of the condenser;
Watch out: there could be a more subtle hazard, even a fire hazard: if the compressor/condenser unit's exhaust is upwards out of the top of the unit (as is often the case) and if it blows up into the air intake of the kitchen exhaust fan while that fan is "on" (such that that fan's outlet baffle is normally blown-open by the kitchen fan) the strong blast of upwards air out of the A/C condenser unit may either close off the kitchen exhaust fan outlet baffle or it might even blow backwards back into the kitchen, risking grease accumulation in the kitchen exhaust, backdrafts, odors, even a fire.
2015/11/06 Tom said:
what is the minimum required distance between a home A/C condenser unit and a fill valve for a home heating oil tank?
Fair question, Tom but I don't know. I've not seen a specific standard for that distance and doubt one exists. In general the condenser ought to be far enough away from the fill and vent valves that there is
- good working space around the condenser unit for maintenance and repair as well as adequate distance from the house wall so as not to obstruct air flow (shown in the article above)
All of that is subjective, but giving the delivery person several feet (3+) ought to be enough in my opinion.
- easy access for your oil delivery driver so she doesn't have to squeeze in between the condenser unit and the wall to reach the fill pipe or listen at the vent pipe; giving plenty of room here for a person to walk and drag a hose also reduces the chance of a splash of waste oil from the nozzle onto the AC unit.
(Jan 29, 2014) David Kutil email@example.com said:
is it possible that having 2 heat pumps next to the house could cause a room to be too cold or too hot? The room next to the two units is always too cold in winter or too warm in summer compared to the other rooms in the house. We were wondering if the air coming off the heat pumps against the side of the house would cause this. The heat pumps blow air up and we can see that the air hits the windows on that side of the house.
I don't think so. It's true that blocking air flow across a heat pump will limit its effectiveness, but I'd be surprised if that showed up as a difference between rooms in the home.
Your question is a good one but I'd be surprised if we could see an indoor effect from air exiting the heat pump.
Use the CONTACT link to send us photos of the installation and I may be able to comment further.
In our sketch above you can see typical air flow patterns from an outdoor central AC compressor/condenser unit. Air enters at the sides and exits at the top of this unit.
So obstructing airflow out at the unit top will also reduce air flow across the condensing coils, shortening equipment life and cutting its efficiency. A rule of thumb is to assure that there is at least 4 ft. above the A./C compressor/condenser unit.
For example, installing an A./C or heat pump compressor under an outdoor deck might block its airflow (not to mention the noise aggravation). In fact typical A/C or heat pump installation instructions recommend that you locate the unit away from windows, patios, decks, etc., where unit operation sound may disturb the customer.
(Dec 2, 2014) steve wilson said:
Will an outside compressor unit get enough air circulation if there is a deck built over it?
Maybe not, Steve. The manufacturer probably specifies a minimum number of feet of clear space above the compressor/condenser unit to avoid restricting its intake or more often outflow.
For example, Lennox air conditioner installation instructions for the compressor/condenser unit typically require 48" of clear space above the unit.
Not to mention people
The most important clearance distances to respect around an outdoor air conditioner or heat pump compressor/condenser unit are with respect to those sides of the equipment through which air is intended to flow - either "in" to the unit our "out" of the unit.
Some outdoor units use a top mounted fan that blows "up" out of the unit, drawing cooling air through the condensing coils at one or more sides of the equipment. For these units both side clearance and top clearance must be respected.
But often the condensing coil does not extend through all four sides of the unit. If this is the case, the distance clearance from the side of a unit through which no air is expected to flow is probably less critical - though you should still be careful that multiple units placed too close together are not competing for the same air.
In our photo above, air moves into this compressor/condenser through three of its sides, but its "back side" (facing the building wall) is not one through which air moves.
Moving an air conditioner compressor to a distance of about 40 feet from a building won't prevent it from working, but the installer might need to adjust the diameter of the refrigerant lines to be sure that the equipment is working at 100% of its capacity.
it's not that the air conditioner won't work at all if the compressor/condenser is located at an unusual distance from the air handler/evaporator coil, it's more that it may lose some capacity and have to work harder - meaning higher electrical bills and in extreme cases, shorter equipment life.
Some air conditioner manufacturers such as McQuay provide a refrigeration piping guide that gives complete, detailed guidance and charts on refrigerant line sizing (diameter) as a function of length of run.
Details about refrigerant piping diameters, distances, and effects on equipment operation are
at REFRIGERANT PIPING INSTALLATION.
Continue reading at COMPRESSOR / CONDENSER INSTALLATION ERRORS or select a topic from the More Reading links or topic ARTICLE INDEX shown below.
Or see COMPRESSOR / CONDENSER REPAIR - topic home
Green link shows where you are in this article series.
OR use the Search Box found below at Ask a Question or Search InspectApedia
(Mar 14, 2015) Anonymous said:
What is the minimum distance for a ac condensor from building?
You will see several building clearance distancesd for A/C compressors, beginning at CLEARANCE DISTANCE, HVAC. There is not one "right" number since as Mark Cramer says, " ... it depends" - in this case clearances are different for the condenser top, sides, and other building features. The smallest of any of these is 6"
Oct 8, 2015) Dick said:
How high off the grounds does a mini split ductless heat pump have to be?
I'm sorry to say, Dick that I have not found anyone specifying a minimum ground clearance distance; for example, a builder can if she wants, set the A/C condenser unit on a concrete slab that happens to be level with the surrounding soil - though that'd be odd. Most pre-fab condenser unit support pads and site built support slabs I've seen put the unit at least 2" above grade, thus reducing the rate of rust and water entry into the bottom of the unit.
(May 13, 2015) Carmen said:
Is there any radiation from it? there is one sitting outside of the master bedroom where there is a wall in between it and the bedside. I wonder how hard and the cost to change it to the kitchen side.
If you are asking about electromagnetic fields created by the electrical equipment in an air conditioner compressor/condenser unit, sure there are modest electrical fields around just about any electrical equipment. The strength of the field falls off with the square of the distance - in other words rather quickly. Unless you're sleeping or spending many hours a day with your head atop the air conditioning compressor, I'm doubtful that there's a measurable electromagnetic field where you are.
Search InspectApedia.com for EMF ELECTROMAGNETIC FIELDS & HUMAN EXPOSURE to read more explanation of this topic.
It is not at all likely to be cost-justified to move an outdoor A/C compressor unit across to the other side of a home to escape its normally-operating electromagnetic field.
(Mar 1, 2015) Mike said:
It is 40 degrees outside and the fan on my packaged heat pump is frozen. This is the first winter since this unit was installed. I've been out two mornings (3am to 9am) defrosting the fan which is frozen to the sides and the fan guard on top of the unit. The coils are not frozen up but there is a solid layer of ice in the bottom that covers the lower 2 inches of the coils and the drain holes which were completely clear the night before.
The ice begins and is thickest nearest the wall. I have to gently melt the ice off the guard, the fan and out of the bottom to uncover the drain holes with a water hose. This unit replaced another package. This unit was supposed to be more efficient because it has a fan discharge on the top. The old unit had side discharge on three sides away from the house. The new unit was placed only 10 inches from the wall which puts the fan under the drip line of the roof. The old unit had 24 inches of clearance and no drip line issues.
The roof rain diverter only extends to cover the width of the old unit plus a foot on either side. The new unit is longer and the end not covered is (of course) where the fan sits. So that is something that must be addressed. However, even if water is not dripping on the unit but there is significant moisture in the air, ice crystals will form from the fan to the side of the fan housing very quickly and will soon freeze up enough to prevent the fan from moving at all.
This only started the end of February and it was been below twenty several days earlier this winter (even though I live in SC). We even had several inches of snow in November. I had no problems until now. As I said earlier, it is 40 degrees this morning. Any ideas?
Is the lack of clearance enough to have it moved to where the old unit was? Will the rain diverter cure the problem or is there more going on? Is the ice conducting the temp of the coils to the sides of the unit dropping it below freezing? Why did it just start now? (I took photos of the configuration and placement)ANY help is great!
I agree that we don't like dumping roof spillage atop an A/C unit and it's also possible that the thicker ice nearer the buiding wall is an effect of differences in air circulation - or perhaps that's where more freezing water is falling from above.
Best: fix the roof drainage and ice dam problems so you're not draining onto the A/C unit.
Search InspectApedia.com (using the on page search box at page top or near the More Reading section at article end) for ICE DAMS and for GUTTERS to see how these problems can be avoided.
You might also construct a protective shed roof over the unit if needed - keep it no less than 48" above the compressor/condenser unit at the roof's lowest point.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
From Google's Contributor website: Contribute a few dollars each month. See fewer ads. The money you contribute helps fund the sites you visit.