Answers and Analysis

Yes, the manufacturer’s specifications should be followed to comply fully with the UMC. UMC Section 103.0 points out that whenever there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable. It also states that the most restrictive requirement shall govern.

The UMC Section 304.1 (2003/2006/2009) and 303.3 (2012) points out that installation of appliances “shall conform to the conditions of listing.” The manufacturer’s specifications and installation instructions are provided to enable the installer to comply with the listing of the appliance.

Condensate drain line traps are not required by the UMC. However, the appliance installation instructions may require the condensate drain line to be trapped at the equipment and shall conform to the conditions of the listing of the appliance as per Section 304.1 (303.1, 2012).

Section 304.2 (303.2, 2009 & 303.3, 2012) applies to central heating furnaces and boilers not listed for closet or alcove installation. The limitation of allowing a maximum of 8 feet to calculate the space is for determining the cubic volume of the space and is not applicable to combustion air calculations. This section is commonly confused with the “confined space” requirement. Additional combustion air is required if a space is determined to be a “confined space” which is a space having less than 50 cubic feet per 1,000 Btu/h of the aggregate input rating of all fuel burning appliances installed in that space. The same 8 foot limitation does not apply when calculating for a confined space.

No, the maintenance platforms are not required. Since the fans are used to ventilate the pool chlorine vapors, the installation would be considered a product conveying system per Section 502.0. Section 503.1 states “Motors and fans shall be accessible for servicing and maintenance.” There is no mention that a platform is required, only that they be accessible. Section 305.0 refers to access for appliances. A ventilation fan does not meet the definition of an appliance in Section 203.0 (2003/2006/2009/2012); therefore a working platform is not required.

No. Section 310.1 (309.1, 2009) (312.1, 2012) of the UMC would prohibit this installation.

Yes. Section 310.1 (309.1, 2009) (312.1, 2012) of the UMC would allow this installation.

No, the roof is not an approved disposal site. One of the basic tenets of the UMC is that no operation of a mechanical system must cause injury to people or damage the building that contains it. The passage of water over any surface (including roofs) will cause erosion. Condensate allowed to pool anywhere could stagnate and allow algae growth that could be a slip hazard. This is one reason why UMC Section 310.1 (309.1, 2009) (312.1, 2012) prohibits draining condensate over a public way. In areas with intense sunshine, water magnifies the damaging effect of the sun, deteriorating the roofing material more rapidly. Condensate from fuel-efficient condensing appliances may be acidic and be deleterious to the roofing material. Any of these problems would preclude the Authority Having Jurisdiction from approving the roof as a disposal area for condensate. Even a landscaped area may not be an approved location if the area is too small and condensate flow from a large building would overwhelm the landscaped area’s ability to absorb it. The code's intent is that condensate be directed to plumbing fixtures or to a disposal area capable of containing and absorbing whatever flow rate may occur without any danger to people or damage to the building.

The main reason condensate pipes must terminate indirectly to an approved receptor is to prevent sewer gas from entering the air stream and to keep sewer and bacteria from backing up into the line which could pose a health risk if it were to contaminate the air conditioning coil. Additionally, it provides a means to verify that the condensate is running free and the unit is operating.

Section 310.1 is not referring to PVC only. Copper may be used if the by-products of the condensate are not considered corrosive to copper. Condensate from some Category II and Category IV direct vent gas-fired equipment is very acidic and could be detrimental to copper. The pH (a logarithmic measure of hydrogen ion concentration) of the condensate would have to be known to determine the proper material to use for the condensate piping if the condensate corrosiveness is questionable.

Section 814.3 of the 2009 Uniform Plumbing Code does recognize a drywell as an approved receptor for condensate waste, although the Authority Having Jurisdiction would have the final approval factoring in the geographical, topographical and climatic conditions in addition to the amount and composition of the condensate being discharged.

Yes. The secondary drain lines function is to give the occupant, where the equipment is installed, an indication that the proper operation of the system has failed. Where damage may occur from overflow, a secondary drain must discharge to a point that can be readily observed per Section 310.2 (309.2, 2009; 312.2, 2012). The secondary drain may terminate to the exterior.

1. No. Section 310.2 (309.2, 2009; 312.2, 2012) does not allow for an alternate in lieu of the required secondary pan or pan with a standing overflow and separate secondary drain.

2. The Administrative Authority can approve alternate materials and methods as long as they meet the requirements of Section 105.0 (2003/2006/2009/2012).

Yes. The intent of Section 310.2 (309.2, 2009; 312.2, 2012) is to protect the structure from damage in the event of an overflow condition. A cooling coil does not have to be concealed to be in a furred space.

Section 101.4.1.4 (2003/2006/2009/2012) of the UPC states in part, "when the requirements within the jurisdiction of this plumbing code conflict with the requirements of the mechanical code, this code shall prevail," meaning Table 8-2 (2003/2006/2009) of the UPC would prevail. However, it should be noted that UPC Table 8-2 was revised in the 2003 edition to match the UMC requirements.

Yes. Section 310.3 (309.3, 2009; 312.3, 2012) of the UMC clearly states that the waste pipe may be for one unit or a combination of units. A 1 inch pipe could adequately handle the condensate for up to 40 tons of equipment capacity.

The provisions for prohibited sources for return air that used to be in the 2000 UMC were deleted from the 2003 and 2006 UMC during the NFPA extraction process. Many people felt that the requirements needed to be added back into the code. As a result of the concern for not having the provisions in the code, a Tentative Interim Amendment (TIA) was submitted first to the Mechanical Technical Committee and then forwarded to the IAPMO Standards Council for final approval. TIA UMC-019-06 was approved by the Standards Council on November 14, 2008. This TIA adds language to Section 312.0 of the 2006 UMC that provides provisions for the installation of return air and is now part of the 2006 Code. Section 312.3 states that outside air or return air for a heating or cooling air system shall not be taken from the following locations: (5) A closet, bathroom, toilet room or kitchen.

This TIA is included in the 2009 UMC Section 311.0

1. Section 402.3 of the 2006 UMC requires that mechanical ventilation systems shall operate so that all rooms and spaces are continuously provided with the required ventilation rate while occupied. Table 4- 4 provides the minimum exhaust rates for toilets. Public toilets rooms require a minimum 50 CFM per water closet or urinal and 70 CFM for periods of heavy use such as for a theatre, school, and sports facility. This would suggest that a continuous exhaust would be required. Private toilet rooms which are intended to be occupied by one person at a time require a minimum of 25 CFM for continuous operation and 50 CFM minimum if a continuous exhaust is not provided. Therefore, a private toilet intended for one person could be controlled by a light switch if a minimum 50 CFM is provided.

2. No, the provisions for prohibited sources for return air that used to be in the 2000 UMC were deleted from the 2003 and 2006 UMC during the NFPA extraction process. Many people felt that the requirements needed to be added back into the code. As a result of the concern for not having the provisions in the code, a Tentative Interim Amendment (TIA) was submitted first to the Mechanical Technical Committee and then forwarded to the IAPMO Standards Council for final approval. TIA UMC-019-06 was approved by the Standards Council on November 14, 2008. This TIA adds language to Section 312.0 of the 2006 UMC that provides provisions for the installation of return air and is now part of the 2006 Code. Section 312.3 states that outside air or return air for a heating or cooling air system shall not be taken from the following locations: (5) A closet, bathroom, toilet room or kitchen.

This TIA is included in the 2009 UMC Section 311.0

The provisions of Section 906.6 of the 2000 UMC are not included in the 2006 UMC. However, Section 904.7 states in part “Furnace plenums and air ducts shall be installed in accordance with … NFPA 90B, Standard for the Installation of Warm-Air Heating and Air-Conditioning Systems.” NFPA 90B Section 4.2.3 Continuous Ducts is quoted as: 4.2.3 Continuous Ducts. (A) Return air shall be conducted to the appliance through continuous ducts, except as permitted in 4.2.3(B) through 4.2.3(E). (B) Underfloor spaces shall be permitted to be used as plenums for return of air from rooms directly above, provided that such spaces are cleaned of all combustible material, are tightly enclosed, and are not used for storage or occupancy. (C) Furnaces, boilers, and other heat-producing appliances shall not be installed in a return plenum. (D) Accessible abandoned materials shall be deemed to be storage and shall not be permitted to remain. (E) In a single-story residence, the return air shall be permitted to travel through the first floor living space to the return air inlet on the furnace (see 6.3.3).

Additionally, UMC Section 904.3 (2003/2006/2009) requires that a furnace shall be installed in accordance with the manufacturer’s instructions.

The provisions of Section 906.6 of the 2000 UMC are not included in the 2006 UMC. However, Section 904.7 states in part “Furnace plenums and air ducts shall be installed in accordance with … NFPA 90B, Standard for the Installation of Warm-Air Heating and Air-Conditioning Systems.” NFPA 90B Section 4.2.3 Continuous Ducts is quoted as: 4.2.3 Continuous Ducts. (A) Return air shall be conducted to the appliance through continuous ducts, except as permitted in 4.2.3(B) through 4.2.3(E). (B) Underfloor spaces shall be permitted to be used as plenums for return of air from rooms directly above, provided that such spaces are cleaned of all combustible material, are tightly enclosed, and are not used for storage or occupancy. (C) Furnaces, boilers, and other heat-producing appliances shall not be installed in a return plenum. (D) Accessible abandoned materials shall be deemed to be storage and shall not be permitted to remain. (E) In a single-story residence, the return air shall be permitted to travel through the first floor living space to the return air inlet on the furnace (see 6.3.3).

Additionally, UMC Section 904.3 (2003/2006/2009) requires that a furnace shall be installed in accordance with the manufacturer’s instructions.

Although the code is silent on the length of the rail, it would seem reasonable that the guardrail extend the entire length of the equipment as a minimum; although, extending it further would provide additional protection. The Authority Having Jurisdiction should have the final decision on what would be acceptable.

No. Section 104.2(2003/2006/2009) and 102.2 (2012) in the UMC states “Mechanical systems lawfully in existence at the time of the adoption of this code may have their use, maintenance, or repair continued if the use, maintenance, or repair is in accordance with the original design and location and no hazard to life, health, or property has been created by such mechanical systems.”

There are no requirements for permanent access on buildings less than 15 feet in height. The Uniform Mechanical Code only addresses buildings greater than 15 feet. The local AHJ would have to determine what is considered “accessible” in their respective jurisdiction.

The light should be installed on the interior of the building to provide adequate lighting for the access means leading to the roof and for the hatch itself. Some hatches have locks that may be difficult to open without proper lighting.

No. Section 311.3 (2) (2009); 314.3 (2012); 311.3 (2015) clearly states that an outside air intake cannot be located less than 10 feet above the surface of any abutting public way, driveway, sidewalk street alley or driveway. Vehicular traffic would not be a deciding factor.

No. A secured permanent ladder is not required under the access panel for maintenance to the units. Section 305.0 (2006); 304.0 (2009); 304.1 (2012) provides the general requirement that the equipment and appliances be accessible.

Section 904.10.3 (2003/2006); 904.10 (2009); 304.2 (2012); 304.3 (2015) only specifies that access to equipment and appliances located on the roof be provided with a permanent ladder if the building is over 15 feet. These sections do not apply to mechanical equipment located within the building.

No, as required by Section 312.5 of the 2012 Uniform Mechanical Code, in order for that condensate drain line to be attached to that tailpiece the occupant of that unit must be the one in control of that unit.
The controlling person would be the end user who would have access. The intent of the UMC is that the condensate wastes connection shall be located in the area controlled by the same person controlling the air-conditioned space.

Yes, Section 304.2 of the 2012 Uniform Mechanical Code would allow the use of an exterior ladder when the building does not exceed 15 feet in height. When equipment or appliances are located on a roof that is greater than 15 feet in height permanently interior ladders shall be installed. The height of the roof above grade is the determining factor, not the number of stories or the occupancy classification of the building.

Yes, this would be correct interpretation.

This would only be applicable to gas dryers unless it is rated for flammable vapor ignition resistant. Section 305.1 of the 2015 Uniform Mechanical Code is only referencing appliances with burners, meaning it is only applicable to gas appliances.

Yes, section 304.1 of the 2015 Uniform Mechanical Code is applicable to appliances as they are located with respect to building construction and other equipment. An “Appliance” as defined in chapter 2 definitions is a device that utilizes an energy source to produce light, heat, power, refrigeration, or air conditioning therefore section 304.1 would apply. For Tankless Water Heaters that are specifically exempt under the UMC Chapter 10 section 1001.1 Exception (1) then the provisions of the Uniform Plumbing Code section 507.26 Accessibility for Service would apply.

Yes, if the kitchen is commonly connected with the living room then, the return air is allowed to be obtained from the kitchen.

No, if the kitchen is isolated from the common space return air cannot be obtained from the kitchen as described in (2015/2018/2021) UMC section 311.3 (5).

If gas appliances are located in designated rooms such as a mechanical room, return air cannot be obtained from those rooms, unlike common rooms containing gas appliances that are described in (2015/2018/2021) UMC 311.3.6 exception (1)

Yes. Although section 310.1 of (2015/2018/2021) Uniform Mechanical Code states that the size of the condensate drain line shall not be smaller than the outlet size in accordance with sections 310.3 and 310.4 where the condensate drain line from an individual condensing appliance shall be sized as required by the manufacturer's installation instructions. As long as the 1" outlet of the condensing appliance is not altered, and the manufacturer does not state that the condensate drain line needs to be 1”, it would be acceptable to reduce condensate drain line to 3/4" using the correct and acceptable drainage fittings, the proper slope and humidity requirements, that would satisfy the equipment capacity in tons of refrigeration for 18 tons using Table 310.3 of The (2015/2018/2021) UMC.

No, except where allowed under section 310.5 of the (2015/2018/2021) Uniform Mechanical Code (Point of Discharge). Prescribed discharge methods include dry wells and leach pits.

Section 315.1 of 2021 Uniform Mechanical Code was originally introduced in the 2010 UMC Report on Comments item 20, with the referenced standards being AMCA 540-2008 and AMCA 550-2009. Both standards are mentioned in Section 315.1 and 345.1.1 and 345.11.2 of the 2021 UMC . In the 2021 UMC Chapter 17 AMCA 540-2013 and AMCA 550-2015 are referenced. However the language in the specific code section was not updated since the original introduction into the UMC.

Concerning section 315.1 of the 2021 UMC, the regulation therein sets 110 and 120 as the minimum wind speed requirements. Historically because IAPMO sets the minimum wind speeds at 110 and 120 compared to the ASCE 7-16 then the louvers in those regions are required to be tested to the Air Movement and Control Association International standards notes in sections 315.1.1 and 315.1.2. It should also be noted that the requirements for Building Envelope Products in ASCE 7-16 are ‘ … typically rated for an allowable stress design wind pressure (0.6W) rather than a strength design wind pressure (1.0W)…’ and this would be more stringent then the UMC and would prevail.

Relief Air is not defined in Chapter 2 of the 2021 Uniform Mechanical Code. However, relief air is referenced in ASHRAE 62.1-2016 (see Chapter 17 of the 2021 UMC). If the Authority Having Jurisdiction classifies the relief air as Class 1, then that air that could be returned to the air-handling unit from the occupied spaces. Under these circumstances the relief air is being discharged to the outdoors to maintain building pressurization (such as during air-side economizer operation).

If however the relief air is classified as Class, 2, 3, or 4, then Table 5.5.1 of ASHRAE 62.1 would be applicable, along with footnote a of the Table: ‘This requirement applies to the distance from the outdoor air intakes for one ventilation system to the exhaust outlets and relief outlets for any other ventilation system.’ Relief air may be contaminated as it exits the building and it is considered “outside” air as noted in this section of the UMC.

Therefore, relief air outlets should shall be located so as to avoid recirculation into the building though relief air is not specifically called out or prohibited in the UMC. If it is Class 2 exhaust air it would be required to be 10 feet away. Relief air classified as Class 3 would need to be separated by 15 feet. Relief air classified as Class 4 would need to be separated by 30 feet.

A mop sink is a plumbing fixture and is generally considered to be a trapped and vented receptor. However, it is the AHJ who would review the listing and certification of the mop sink and determine if it can be approved as an indirect waste receptor for condensate waste.

The 2015 Uniform Mechanical Code does not include a definition for plumbing fixtures. However under section 302.1 of the 2015 UMC, the Authority Having Jurisdiction would approve any appurtenances to the mechanical system.
• The 2015 Uniform Plumbing Code under section 218.0 defines a plumbing fixture as: An approved-type installed receptacle, device, or appliance that is supplied with water or that receives liquid or liquid-borne wastes and discharges such wastes into the drainage system to which it may be directly or indirectly connected. Industrial or commercial tanks, vats, and similar processing equipment are not plumbing fixtures, but may be connected to or discharged into approved air gaps or plumbing fixtures where and as otherwise provided for elsewhere in this code.
• The 2015 UPC under section 220.0 defines a receptor as “An approved plumbing fixture or device of such material, shape, and capacity as to adequately receive the discharge from indirect waste pipes, so constructed and located as to be readily cleaned.”

For the mop sink to receive the waste from AC coils the following conditions must also be met:
1. It has a proper air break or air gap.
2. It does not interfere with the use and function of the mop sink.
3. It does not violate any adopted local codes or ordinances.
4. If there were multiple AC appliances going to mop sink, you would need to have the proper size trap as regulated by the Uniform Plumbing Code.

1. Yes, the intent is to be able to remove the largest component of the equipment such as a fan, motor etc. An “Appliance” as defined in Chapter 2 Definitions is a device that utilizes an energy source to produce light, heat, power, refrigeration, or air conditioning therefore section 304.1 would apply to the fan coil. The access panel would not need to be sized allowing for the whole Fan Coil, but enough to service it and remove components (e.g. blower motor), but sized for the largest component to be removed and replaced, or if size of the largest component was less than the size of an individual suspended ceiling panel access could be provided at that point. Removal of the suspended ceiling main tees and cross tee do not meet the intent of the 2015 Uniform Mechanical Code. The suspended ceiling main tees and cross tee are considered permanent construction.

You must be able to access any part or component and be able to service and maintain the unit or appliance without obstruction. Service implies preventative maintenance and emergency repairs. It does not mean full replacement. A fan coil unit is not installed with the intent that it should be replaced completely without disturbing aspects of the building.



2. Cutting a hard lid is not acceptable. You would need a access panel. A hard lid would be considered permanent construction therefore concealing the unit. See “accessible and readily accessible in section 203 in chapter 2 of the 2015 UMC.

No, unless the distance from the environmental exhaust termination opening is a minimum of ten feet from the outside air intake opening.Section 502.2.1 of the 2021 Uniform Mechanical Code provides the requirements for the termination of the exhaust ducts for Environmental Air; exception 1 section 311.3 addresses the outside air for the heating system specifically.