Thread: Minimum clearance between air-cooled condensing units

Does anyone know if there is a code that defines the minimum clearance between residential size air-cooled condensing units? I know most manufactures will publish minimum recommended clearances; however, I have a client who was told that the condensing units at his multi-family property were not "code" cause they were too close together. Thanks in advance.

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Originally Posted by Michael Choffin

Does anyone know if there is a code that defines the minimum clearance between residential size air-cooled condensing units? I know most manufactures will publish minimum recommended clearances; however, I have a client who was told that the condensing units at his multi-family property were not "code" cause they were too close together. Thanks in advance.

It is going to be a manufacturers requirement for each unit, it is not a code requirement unless the AHJ has one. You do need a working clearance area of 30"x36" for the electrical, that is a code..

I know that some require side clearances of 18", 24" and even 30". It all depends on the units. You can contact the manufacturer and they will be glad to tell you.

Ask the person to cite the code if they say it is!

Originally Posted by Michael Choffin

Does anyone know if there is a code that defines the minimum clearance between residential size air-cooled condensing units? I know most manufactures will publish minimum recommended clearances; however, I have a client who was told that the condensing units at his multi-family property were not "code" cause they were too close together. Thanks in advance.

As you likely know the manufacturer's requirement IS code. As such it will vary according to the brand and model of unit as to air clearance.

I find that some people tend to throw the word "code" around rather loosely. I'm aware that each manufactures publishes their recommended clearance. Most tend to be between two to three feet depending on the size of the unit and what direction the air is discharged. I was looking for a reference such as International Mechanical Code, International Building Code or Uniform Mechanical Code.

Thanks for the help.

The most common clearance requirement is 12" between one condenser unit and anything that blocks or restricts the air, and that twice that (24") between to units.

There have been some installation instructions which have allowed that 24" between unit to be reduced to 12" as long as there was at least 12" on all other sides (which means the 112" is not applied to the center unit of 3 condenser units installed side-by-side-by-side.

I have also seen installation instructions which stated 12" on one side, 9" on another side, 6" on the third side, and no clearance stated on the remaining side (by a little thinking about the drawing showing the clearances reveals that the remaining side is the 'service side' and requires 36" for working space ).

The greatest clearance I have seen in installation instructions has been ... 80"!

NEC (2005 Ed. with Batavia special ammendments), which the listing standards and listed manufacturer's instructions in Chapter one; depending on location of local shut-off and fuse/circuit breakers access clearances to same, Clearances not only for operation, but for cleaning and servicing the units (all sides) and local (Batavia, IL) zoning code, set-off and set-backs, and required screening all occupancies (even roof installations multi-family). Other than 1-2 family, according to Batavia's web published code, IBC 2006 with Batavia ammendments would apply, IMC 2006 with Batavia ammendments, and possibly Illinois Plumbing Code.

While Mfg. recommedations should be followed and clearances cited ring true, regarding space between units, other factors should be considered. Does placement disrupt the efectiveness of other building components

Avoid backdrafting at exhaust vents. - All to often I see placement under dryer vents, thru the wall water heater vents etc. When condensing units are running a push back into exhaust vents may occur.

Energy efficiency - unit A is running, discharging -heat- toward unit B. Unit C is running, discharging -heat- toward unit B. How much more work -energy- does it take for unit B to do it's job?

Related topic on clearance issues - Have you observed the results of placing an outdoor gas barbeque grill, very close to a wall clad in vinyl siding?

Clearance required for sevice to the condenser controls is 24" , since most condensers have a service panel on the corner of the unit it's safe to say that with multiple condensers at least 1 access would be between the units requireing a 24" space. Most mini split systems also require a 24" clearance.

Originally Posted by David Bell

Clearance required for sevice to the condenser controls is 24" , since most condensers have a service panel on the corner of the unit it's safe to say that with multiple condensers at least 1 access would be between the units requireing a 24" space. Most mini split systems also require a 24" clearance.

The working space required for service to the condenser controls is ... 36".

The mechanical code only requires 30", however, if the condenser unit has electric wiring to it of any type then the condenser unit is also "electrical equipment" and the required working space for "electrical equipment" is 36" in front of the service area.

CCF10162010_00000.jpgThis is what I see out there for the most part.

My opinion: when the issue is the required clearances for cooling, always check the MII, I've sometimes been surprised by the required clearances (usually, because they were tighter than expected).

Originally Posted by David Bell

CCF10162010_00000.jpgThis is what I see out there for the most part.

And this is what you should be installing by MINIMUM:
From the IRC:
- M1305.1 Appliance access for inspection service, repair and replacement. Appliances shall be accessible for inspection, service, repair and replacement without removing permanent construction, other appliances, or any other piping or ducts not connected to the appliance being inspected, serviced, repaired or replaced. A level working space at least 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. Installation of room heaters shall be permitted with at least an 18-inch (457 mm) working space. A platform shall not be required for room heaters.

From the NEC:
- 110.26 Spaces About Electrical Equipment.
- - Sufficient access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment.
- - - (A) Working Space. Working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (A)(2), and (A)(3) or as required or permitted elsewhere in this Code.
- - - - (1) Depth of Working Space. The depth of the working space in the direction of live parts shall not be less than that specified in Table 110.26(A)(1) unless the requirements of 110.26(A)(1)(a), (A)(1)(b), or (A)(1)(c) are met. Distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed.
- - - - - Table 110.26(A)(1) Working Spaces specifies the minimum clearance in front of the equipment to be 36 inches, and the clearance goes up for some conditions where the voltage to ground is 151-600 volts to ground (not seen in the typical residence).

So now you have:
a) Manufacturer's installation instructions which state 24 inches.
b) IRC which states 30 inches in the mechanical section.
c) NEC (and its equivalent in the IRC requires the same thing) which states 36 inches.

Q. So which *are you supposed to* go by?
A. (from the IRC): R102.1 General. Where, in any specific case, different sections of this code specify different materials, methods of construction or other requirements, the most restrictive shall govern. Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable.

Note that manufacturer's installation instructions are 'code by reference' and therefore fall under "the most restrictive shall govern", i.e., *IF* the manufacturer's installation instructions specified 42 inches clearance, that would be the requirement as it would be "the most restrictive", however, lacking that, "the most restrictive" applies - the NEC working space requirements.

I'm not trying to get in a code war with you, but 110-26a 1, 2 and 3 all seem to deal with interior installations. I'm probably wrong (and I'm sure I'll hear about it). But it does seem that way. Enlighten me!

Originally Posted by David Bell

I'm not trying to get in a code war with you, but 110-26a 1, 2 and 3 all seem to deal with interior installations. I'm probably wrong (and I'm sure I'll hear about it). But it does seem that way. Enlighten me!

David,

(bold and underlining are mine)
- ARTICLE 110 Requirements for Electrical Installations
- - I. General
- - - 110.1 Scope.
- - - - This article covers general requirements for the examination and approval, installation and use, access to and spaces about electrical conductors and equipment; enclosures intended for personnel entry; and tunnel installations. (Jerry's note: Nothing in there about interior installations.)
- - - 110.26 Spaces About Electrical Equipment.
- - - - Sufficient access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment.
- - - - - (A) Working Space. Working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (A)(2), and (A)(3) or as required or permitted elsewhere in this Code. (Jerry's note: Nothing in there about interior installations.)

Now, when you get past 110.26(A) and get down to 110.26(F), in (F) "Indoor" and "Outdoor" do have different requirements - but, (S) is "working space", and (F) is "dedicated space", which are different animals.

110.26(A) is just as applicable to service equipment "outdoors" as it is to service equipment "indoors", and it is applicable to all "electrical equipment" which is "likely to require examination, adjustment, servicing, or maintenance while energized".

Thus, one would need to know what electrical "equipment" is defined as in the NEC:
Equipment. A general term, including material, fittings, devices, appliances, luminaires, apparatus, machinery, and the like used as a part of, or in connection with, an electrical installation.

Notice that electrical "equipment" also includes "material, fittings", however, "material, fittings" are unlikely to be require examination, adjustment, servicing, etc., "while energized". I.e., one would typically turn the power (breaker/fuse) off before pulling wire out of a raceway to replace a broken fitting or broken section of the raceway. Agreed?