Every week we will be including additional questions and informal UPC and UMC interpretations
- In the UMC regarding a room containing the refrigerant compressors for a large grocery store: 1. When the refrigerant quantities in a single system exceed the amounts in Table 11-1 for a single system, which would otherwise require a refrigeration machinery room, can the room be designed so that it is open to either the main floor or other areas that are large enough to meet the allowable quantities as shown in Table 11-1 to eliminate the need for the refrigeration machinery room? 2. Does footnote 7 of Table 11-1 indicate that this table, pounds per 1000 cubic feet of occupied space, is not applicable for determining when a refrigeration machinery room is necessary?
- 1. Anytime the amount of refrigerant in a system exceeds the allowable amount in Table 11-1, a machinery room is required. Additionally, if an A1 system having an aggregate combined compressor horsepower of 100 (73.55 kW) or more, a machinery room is required. Since the table is based on cubic volume of space, all areas that freely communicate with the space could be used to calculate the volume. The concern would be the size and location of the communicating opening which would have to be determined and approved by the AHJ. 2. No. Footnote 7 clarifies that refrigeration machinery rooms and cooling systems used for human comfort are not subject to being sized based on pounds of refrigerant per cubic foot of space.
- Does UPC require all bathtubs to be equipped with an overflow? If so, what section?
- The Standards for fixtures listed in Table 1401.1 (2009/2012), Table 1701.1 (2015) all indicate that overflows are required on bathtubs and whirlpool bathtubs. These same Standards indicate that the overflow requirements are optional for sinks, lavatories and bidets. If an overflow is provided with a fixture, section 403.0 (2009); 404.0 (2012/2015) shall be followed for proper installation. Section 409.3 is referring the installer to section 403.0 (2009); 404.0 (2012/2015) to guide the installer on how to pipe the overflow that is provided on a Bathtub or whirlpool bathtub.
- According to the UMC venting tables, the NR designation means "not recommended." Does "not recommended" mean the same as do not install venting this way?
- The NR designation is similar to the NA designation in the UMC. It indicates a configuration that is not permitted. The solution is usually substituting a double-wall connector for a single-wall. The lengths of single-wall connectors that may be used are limited due to the heat loss of this vent material. The vent gas heat loss causes excessive condensation in the vent and eventual failure.
1. Is a future gas “stub-out” required to be provided with a shutoff valve and cap? 2. Is a capped outlet without a shutoff valve considered a completed gas system?
1. No. The minimum requirement is a cap. 2. Yes.
- Is Teflon tape an approved pipe joint material for gas pipe installations?
- Yes, listed Teflon tape is acceptable when carefully and correctly applied to male threads only, since it is insoluble in the presence of fuel gas.
- In the UPC, 1. Would a 4' long drain tail piece require support for vertical piping? 2. Would the no-hub coupling installed at the floor drain on the top of the pipe provide support to the piping? 3. Would the no-hub coupling installed at the base of the pipe at the 90 degree fitting provide support?
- 1) No. A fixture tail piece is limited to 24 inches. If the fitting that connects the tail piece to the fixture is properly supported the tail piece would not need further support. 2) No. You should not rely on no-hub couplings to support the weight. 3) No. No-hub couplings are designed as a means to provide a water tight joint, not to support pipe. The 90 degree fitting must be properly supported.
- The UMC appears silent on the length of the guardrail. How long should the guardrail be? I propose it should extend at least 6 feet from any part of the rooftop equipment. What guidance can you give concerning the length of the guardrail?
- 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.
- Does the UPC allow a gas line to pass completely under a building from one side to the other if it is sleeved and vented per 1211.1.6 (2009); 1210.1.6 (2012/ 2015)?
- Section 1211.1.6 (2009); 1210.1.6 (2012/ 2015) states, “Where the installation of gas piping underground beneath buildings is unavoidable the piping shall be encased in an approved conduit…” The local AHJ shall determine if an alternate route for the gas line exists.
- UMC Section 609.0 states that, "Air-moving systems supplying air in excess of 2,000 cubic feet per minute to enclosed spaces within buildings shall be equipped with an automatic shutoff." I have a small service area open to a main display area, (i.e. no enclosing walls) that is conditioned with two heat pumps, each has a separate duct supply and return air.
- Each heat pump supplies 1,100 cubic feet per minute supply air for a total 2,200 cubic feet per minute to the service area.
- Are smoke detectors required on each heat pump supply air duct?
- Yes, the key to the code section is the definition of air-moving systems. This definition states that an air-moving system comprises one or more air-handling units being used to supply air to a common space or are drawing air from a common space. Therefore, since the units are serving a common space and the aggregate cubic feet per minute exceeds 2000 cubic feet per minute, each unit shall be equipped with smoke detectors as required in Section 609.0. The requirement for automatic shutoff may be omitted if the system meets one of the exceptions.
- Does a roof drain overflow require a strainer?
- Yes, an overflow drain is still basically a roof drain in the event a primary drain becomes plugged, and therefore, the strainer requirement of Section 1105.2 (2003/2006/2009/2012) 1102.2 (2015) applies. The only time an overflow drain would normally come into use would be due to a blockage of the strainer on the primary drain. This blockage could be caused by accumulation of debris on the roof which could enter the drainage system through an unprotected overflow, rendering the entire storm drainage system inoperative. The strainer requirement would be the same, whether the overflow were installed on either a vertical or a horizontal plane.
- Is it mandatory to comply to the present code when chillers are replaced or do the old requirements from the original installation still apply?
- Yes, as stated in Section 103.0 (101.3, 2012), "Additions, alterations, repairs and replacement of equipment or systems shall comply with the provisions for new equipment and systems..."
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