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Gas Appliances and Flexible Connectors

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Gas Appliances and Flexible Connectors

By Skip Walker

September 2010


How many times have you seen flexible gas connectors routed through walls, cabinets, flex connectors in the crawlspace used in lieu of rigid piping, old connectors on a brand new water heater, multiple connectors daisy-chained together, etc?   When you comment on these conditions, some percentage of the time you are bound to receive a phone call or an email later from the agent.  Invariably, the plumber said “that's the way its done here”, the HVAC contractor didn't understand what was wrong or perhaps to let you know that the building inspector signed off on the permit.

The simple truth is, this is a confusing topic.  There are varying opinions as to what is “right” and what is “wrong.”  While the fuel gas code  directly addresses most common installation conditions/defects,  others require a little sleuthing work.  As we will see, the cabinet sidewall question seems to be one with no readily available, cut and dried answer.

To understand how gas connectors should be used, it is important to understand what a connector is and just as importantly – what they are not.  Flexible gas connectors must conform to ANSI Standard z21.24.  The ANSI z21.24 Standard applies to new flexible gas connectors.  Both the standard and the manufacturers installation instructions preclude re-using an old connector.

A small amount of the standard text is available on the ANSI site.  Unfortunately, this section did not answer all questions.  ANSI charges $525 for a copy of the 66 page standard.  When I checked last Sunday's numbers, I hadn't hit the Lotto, so purchasing a copy of the standard for this article was not in the budget.  Attempts to contact Dormont, one of the largest connector manufacturers, were unanswered as of the time this article was due.

The fuel gas piping sections in both the 2007 California Plumbing Code (CPC) and 2007 California Mechanical Code (CMC) are derived from NFPA 54 The National Fuel Gas Code.  The relevant sections of the CPC are in Chapter 12 Fuel Gas.  The relevant portions of the CMC are in Chapter 13.

As part of the research for this article, I requested a clarification from NFPA on NFPA 54,section 9.6 which deals with flexible gas connectors.  In the NFPA clarification,  Denise Beach, Senior Engineer NFPA, stated that A concealed space in NFPA 54 is an area that is concealed by construction, such as the hollow area inside a wall, or the area above a drop ceiling.  I have never interpreted piping or tubing passing through a floor assembly to a lower level to be a concealed space installation.  I have also never considered a cabinet to be an area subject to damage, even if it is used for storage.  To my knowledge, the National Fuel Gas Code Committee has not received any reports of damage to appliance connectors in these types of installations.” Given the NFPA position drop ceilings, the position on floor assemblies seems surprising. While this interpretation may allow the flexible material to pass through a floor, it seems prohibited elsewhere.  The cabinet issue is less clear-cut and only points to the lack of clarity in the codes on this issue. The manufacturers installation instructions could be interpreted as not allowing cabinet panel penetrations, but stop short of specifically disallowing the installation.

The manufacturers installation instructions provide useful information.  On page 4 of the Dormont manual it says, DO NOT install the gas connector so that it is concealed within or runs through any wall, floor or other partition. The gas outlet must be in the same room as the appliance.  This is so it is visible for periodic inspection and further To avoid corrosion, DO NOT allow connector to come in contact with foreign objects such as wall studs, electrical wiring, copper or iron pipe, paneling, sheet metal, etc”.

The code definition of fuel gas piping is important to better understanding the issues.  Per the 2007 CMC gas piping is defined as all the pipes, valves and fittings used to convey fuel gas withing the dwelling.  The gas piping does not include the service piping.  The CA codes do not regulate utility owned piping and components.  Those components are regulated by the Public Utilities Commission (PUC).  The gas piping stops at the gas outlet.  The gas outlet is considered to be the point of attachment for the appliance or consuming device. This is generally considered to be the appliance gas shut-off valve.  The outlet must be located in the same room as the appliance served and within six (6) feet of the appliance.

See the 2007 CPC Section Below:

2007 CPC 1203.4 Gas Piping. Any installation of pipe, valves, or fittings that is used to convey fuel gas, installed on any premises or in any building, but shall not include:

(1) Any portion of the service piping.

(2) Any approved piping connection six (6) feet or less in length between an                existing gas outlet and a gas appliance in the same room with the outlet.


In CPC Section 1203.4, the definition of gas piping excludes a flexible connector.  So the flexible connector is not service or supply piping.  This section also tells us that the connector must be in the same room as the appliance and that the maximum length is 6 feet.

CPC Section 1210 contains the requirements for connection gas utilization equipment to the gas piping system.

2007 CPC 1212.1 Connecting Gas Equipment. Gas utilization equipment shall be connected to the building piping in compliance with Sections 1212.4 and 1212.5 by one of the following: [NFPA 54: 9.6.1]

1. Rigid metallic pipe and fittings.

2. Semi-rigid metallic tubing and metallic fittings. Aluminum alloy tubing shall not be used in exterior locations.

3. Listed flexible gas connectors in compliance with ANSI Z21.24, Standard for Connectors for Gas Appliances. The connector shall be used in accordance with the terms of their listing that are completely in the same room as the equipment.

4. CSST where installed in accordance with the manufacturer's installation instructions.

5. Listed nonmetallic gas hose connectors in accordance with 1212.2.

6. Gas-fired food service (commercial cooking) equipment listed for use with casters or otherwise subject to movement for cleaning, and other large and heavy gas utilization equipment that can be moved, shall be connected in accordance with the connector manufacturer's installation instructions using a listed appliance connector

7. complying with ANSI Z21.69, Standard for Connectors for Movable Gas Appliances.  [NFPA 54:]

8. In 1212.1(2), (3), and (5), the connector or tubing shall be installed so as to be protected against physical and thermal damage. Aluminum alloy tubing and connectors shall be coated to protect against external corrosion where they are in contact with masonry, plaster, or insulation or are subject to repeated wettings by such liquids as water (except rain water), detergents, or sewage.


In Section 1212.1, flexible connectors that conform to ANSI z21.24 are specifically allowed as a method to connect utilization equipment to the gas piping system.  Corrugated Stainless Steel Tubing (CSST) is also allowed when installed per the manufacturers installation instructions.  It is important to note that flexible connectors are not CSST and vice versa.  They are distinctly different products.  CSST is an engineered gas piping system.  The NFPA 54 committee is considering a clarification to NFPA 54 Section 9.6 that specifically requires that when CSST is directly connected to the utilization equipment, that it meet both the requirements of the CSST specifications and z24.21.  This does not appear to have been adopted into the code as of yet.


2007 CPC 1212.4 Equipment Shutoff Valves and Connections. Gas utilization equipment connected to a piping system shall have an accessible, approved manual shutoff valve with a non-displaceable valve member, or a listed gas convenience outlet [NFPA 54: 9.6.4], installed within 6 feet of the equipment it serves. Where a connector is used, the valve shall be installed upstream of the connector.  A union or flanged connection shall be provided downstream from this valve to permit removal of controls.  Shutoff valves serving decorative gas appliances shall be permitted to be installed in fireplaces if listed for such use. [NFPA 54:]


Section 1212.1 requires that there be a dedicated appliance shut-off valve installed upstream of the flexible connector.  It also requires either a union or flanged connector between the valve and the appliance.  The flexible connector includes a flanged connector and fulfills this requirement.


The exceptions in 2007 CMC Section 1312.4 allow gas shutoff valves to be located inside or under an appliance only when the appliance can be removed without removing the shutoff valve.  The exception also allows shutoff valves to be located inside wall heaters and wall furnaces listed for recessed installation where necessary maintenance can be performed without removal of the shutoff valve.


Per 2007 CPC Section 1212.7, a sediment trap is not required where a trap one is not incorporated as a part of the gas utilization equipment.  The sediment trap should be be installed as close to the inlet on the gas utilization equipment as practical at the time of equipment installation. The sediment trap can be either a tee fitting with a capped nipple in the bottom or another device recognized as an effective sediment trap.  Illuminating appliances, ranges, clothes dryers, decorative vented appliances for installation in vented fireplaces, gas fireplaces, and outdoor grills are not  required to have sediment traps installed.


What can we take away from this discussion?  It seems that most of what we call in a typical gas installation is fairly well defined between the codes and the manufacturers installation instructions.  The issue of a flex connector through a cabinet sidewall is less clear and subject to interpretation.  In my market area, most jurisdictions do not allow the practice.  However, one does.  They are all looking at the same document and yet draw different conclusions.  What about us as general property inspectors?  What we do is not  a code compliance inspection.  You may feel that this issue poses a safety concern.  If that is your opinion, then it is a reportable condition.  Local jurisdictional interpretations may or may not concur.  I will be updating this article as more information becomes available.  Please check the eNews section on the CREIA for updates.



About the author:

Skip Walker lives in the SF Bay Area and has performed approximately 2,700 paid inspections since becoming a CREIA member in 2003.  Skip is both a CREIA Master Inspector and an ASHI Certified Inspector.  Skip is an ICC Certified Residential Combination Building Inspector and a F.I.R.E. Certified Inspector.  Skip is the current CREIA Region Three Director, current CREIA State Secretary and past Education Chair and ASHI President at the Silicon Valley ASHI/CREIA Chapter.  He also holds a California Real Estate Appraisal Trainee License. Skip may be reached at



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