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Sleeper Sofas and Gas Appliances

January 14, 2019 by Roger Griffith Leave a Comment

Gas appliances could pose a threat to people when they are sleeping, unaware of any impending danger. The threats include oxygen depletion and elevated levels of nitrous oxide or carbon monoxide. For this reason, the fuel gas codes restrict the use of gas appliances in sleeping rooms.

The 2018 International Fuel Gas Code (IFGC), Section 303 – Appliance Location contains the following criteria.

303.3 Prohibited Locations. Appliances shall not be located in sleeping rooms, bathrooms, toilet rooms, storage closets or surgical rooms, or in a space that opens only into such rooms or spaces, except where the installation complies with one of the following:

There are six exceptions listed for paragraph 303.3. These six exceptions allow gas appliances in these prohibited locations when specific conditions are met. These exceptions are:

Exception #1 allows a direct vent appliance.
Exception #2 allows vented room heaters, wall furnaces, vented decorative appliances, vented gas fireplace heaters, and decorative appliances installed in vented solid fuel-burning fireplaces that meet the volume criteria of Section 304.5.
Exception #3 allows unvented room heaters meeting specified criteria in bathrooms.
Exception #4 allows unvented gas appliances meeting the specified criteria.

Exception #5 allows appliances to be installed in adjacent rooms that open to a bedroom or bathroom if these rooms are weather-stripped and have a self-closing door.
Exception #6 allows a clothes dryer to be installed in a bathroom if certain criteria is met.

Exceptions 1, 2, and 4 apply specifically to sleeping rooms/bedrooms. The intent from these paragraphs is clear. Gas appliances in sleeping rooms are permitted only if the appliances are direct-vent, vented, or unvented if the unvented appliances meet all of the following conditions:

The unvented gas appliance (one) is a wall-mounted room heater.
The unvented, wall-mounted, gas room heater is equipped with an oxygen depletion safety shutoff system, as required by Section 621.6.
The unvented, wall-mounted, gas room heater has an input rating of not more than 10,000 Btu/hr.
The room is large enough to provide adequate combustion air as described in Section 304.5.

Note that the IFGC limits unvented gas appliances in a sleeping room to a “wall-mounted” heater. This precludes unvented heaters that stand on the floor, fasten to a fireplace hearth, or are ventless firebox hearths.

These restrictions for gas appliances are typically applied to bedrooms. Notice though the terminology used in Section 303.3 does not restrict gas appliances in bedrooms but in sleeping rooms, which has a broader definition.

Code officials may interpret the presence of a sleeper sofa in a room as making that room a sleeping room, and I believe rightfully so. Sleeper sofas may be present in condominiums, hotels, apartments, time-shares, and other residential/hospitality occupancies.

If there are depleted oxygen levels or elevated levels of nitrous oxide or carbon monoxide present, whether someone is sleeping on a bed in a bedroom or on a sleeper sofa bed in some other room, the risks are the same.

Just be aware that, in jurisdictions where the International Fuel Gas Code is adopted, the presence of a sleeper sofa may mandate compliance with the restrictions for gas appliances in sleeping rooms/bedrooms.

Careful! The Wrong Showerhead May Scald You

January 7, 2019 by Roger Griffith Leave a Comment

If not specified and installed correctly, showerheads can cause scalding!

Currently, standard shower valves and showerheads have a minimum flow rate of 2.5 gpm. There are water-saving shower valves and showerheads available with lower flow rates. WaterSense showerheads are rated at 2.0 gpm. There are also showerheads available that have 1.5, 1.0, and even 0.5 gpm flow rates. These various options for minimum flow rates in shower valves and showerheads create an opportunity for misapplication and dangerous results.

When the flow rate of a showerhead is less than the minimum flow rate of the corresponding shower valve, the potential for scalding increases for the following reasons:

Discharge Temperature Ranges Can Increase

Shower valves provide protection from scalding and thermal shock. The plumbing codes require shower valves to conform to the requirements of ASSE 1016. To meet the requirements of ASSE 1016, shower valves are tested at their rated flow. Shower valves are not required to be tested at flow rates less than the published minimum flow rate of the valve. To comply with ASSE 1016, at the rated flow the discharge temperature of the shower valve must be maintained within a range of +/- 3.6°F when inlet cold and hot water pressures and/or temperatures are varied. When a water-saving showerhead limits the actual flow through the shower valve to less than its rated flow, the shower valve may not maintain the discharge temperature within the required temperature range. Wider ranges of discharge temperatures can contribute to scalding or thermal shock.

Less Flow Reduction Can Occur On Loss of Water Supply

ASSE 1016 Type P pressure-balancing shower valves, which are the most common type of shower valves, are tested to ensure that on a loss of cold water or hot water flow, the discharge flow from the shower valve will reduce within five seconds to 0.5 gpm or 30% of the minimum flow, whichever is less, to reduce the risk of scalding or thermal shock.

For example, upon a loss of cold water, an ASSE 1016 shower valve with a minimum flow rate of 2.5 gpm and a 2.5 gpm showerhead will reduce the flow to 0.5 gpm, which is 20% of the minimum rated flow. This significant flow reduction from 2.5 gpm to 0.5 gpm alerts the user, providing protection from scalding or thermal shock. But if the showerhead has been replaced with a high-efficiency, water-saving 1.0 gpm showerhead, upon loss of cold or hot water flow, the discharge flow rate may only be reduced from 1.0 gpm to 0.5 – 0.75 gpm. This reduces the flow to only 50 – 75% of the operating flow, not 20 – 30% as intended by ASSE 1016, which may not be sufficient to prevent scalding or thermal shock.

A Greater Potential for Crossflow Exists

A showerhead, with a flow rate below the shower valve’s, effectively creates a restriction in the flow stream in the line between the shower valve and showerhead causing a higher pressure in the line versus the pressure in the line when the shower valve and showerhead have matching flow rates. This higher pressure creates a greater potential for cross-flow at the shower valve from the hot water supply into the cold water supply. With crossflow, hot water can exit the cold water faucet at a nearby fixture.

Manufacturers and many in the industry are aware of this potential risk for scalding. Minimum flow rates for shower valves and showerheads are now included in the packaging and instructions for the fixtures.

The 2018 Uniform Plumbing Code (UPC) added a requirement that the flow rate of the showerhead cannot be less than the minimum flow rate of the shower valve. A similar requirement will be proposed and voted on in the upcoming 2021 International Plumbing Code cycle.

Roger W. Griffith appointed to ICC Plumbing/Mechanical/Fuel Gas Code Action Committee

January 27, 2017 by Roger Griffith Leave a Comment

The Plumbing/Mechanical/Fuel Gas Code Action Committee (PMGCAC) of the International Code Council (ICC) reviews and proposes revisions to the International Plumbing, Mechanical, Fuel Gas, Private Sewage Disposal, and Swimming Pool and Spa Codes and the International Residential Code, chapters 12 through 33. I am honored to be appointed as a member of this committee for the upcoming 2018 – 2019 code development cycle.

These important codes define how mechanical, plumbing, and fuel gas systems must be designed and installed to protect the health, safety, and welfare of the public.

Tools and Resources for Mechanical Insulation

November 26, 2016 by Roger Griffith Leave a Comment

When designing mechanical systems, engineers and designers often need help specifying the type and thickness of insulation for ducts and piping. Good resources are always valuable and welcome when time constraints leave little time for items like insulation and other accessories.

The National Insulation Association’s (NIA) new redesigned website is a helpful resource for all things insulation, from training, design helps, and specifications. Check out their new website and bookmark it for return trips. Enjoy!

Can Sprinklers Removed From A System Be Reattached?

July 12, 2016 by Roger Griffith Leave a Comment

There is much debate in the industry and within code committees about the reuse of sprinklers. A recent article on the NFPA website provides clear guidance about past and current code requirements for sprinkler reuse. They nailed it! Provided below is the article in its entirety (emphasis – mine).

BY MATT KLAUS

A hot topic over the last two revision cycles of NFPA 13, Installation of Sprinkler Systems, has been the reuse of sprinklers. Over the last 10 to 12 years, there has been a reduction in new commercial construction as many companies sought more cost-effective alternatives, including renovating or rehabilitating existing buildings. Many of these renovated buildings had automatic sprinkler systems in place when the new owners moved in. Due to the relocation of partitions, suspended ceilings, structural members, and other architectural features, however, sprinklers may need to be relocated to comply with the location and spacing requirements of the standard.

This raises a number of questions, including whether or not a sprinkler can be reused after it’s been removed from the system. In some cases, the sprinkler may be detached from the system for only a matter of hours, and in other cases it could be months. Regardless, the duration that the sprinkler is out of service is not the deciding factor in whether it can be reinstalled. According to NFPA 13, that depends on whether torque was applied directly to the sprinkler when it was removed.

During the development of the 2013 edition of NFPA 13, the Technical Committee for Sprinkler System Installation Criteria added language that said, “When a sprinkler has been removed for any reason, it shall not be reinstalled.” While this language seems cut and dried, there was a nuance to it that was brought out in the committee discussion during the second draft meeting. The intent of the committee was to prohibit the reuse of sprinklers when torque was applied directly to the wrench boss of the sprinkler during its removal, a practice that can damage the sprinkler. In situations where sprinklers are on sprig ups, return bends, drops, or other fittings, the sprinkler and its associated fitting(s) could be reinstalled provided the sprinkler was removed by applying torque to a fitting rather than the sprinkler itself. While this language was not explicit in the 2013 edition, the technical committee revised the text to the 2016 edition to spell this out more clearly.

The logic behind this requirement is that applying torque to the sprinkler itself could lead to damage to the threads, seat, bulb, or other critical components. In many cases, this damage is imperceptible to the naked eye, so a visual inspection would not be sufficient to determine if the device has been compromised. A damaged sprinkler that is reinstalled could lead to an accidental discharge during a hydrostatic test or when the system is placed under working pressure.

During the development of the 2016 edition, the committee further developed this concept by including a new allowance for dry sprinklers to be put back into service after being taken down. Dry sprinklers are more expensive than a standard spray sprinkler installed in a wet system, and the manufacturers and other committee members were sensitive to forcing owners to buy new dry sprinklers simply because they needed to be relocated. The standard now has language that allows dry sprinklers to be put back into service where they were taken down in accordance with the manufacturer’s instructions.

This issue has been the subject of some intense discussion by the technical committee, which is trying to find a balance between cost and safety. The committees are preparing for the development of the 2019 edition of the standard, so if you have any input on this topic, share your opinion by using the public input/comment process on the NFPA 13 document information webpage.

How To Design Plumbing Systems To Minimize Legionella

August 28, 2015 by Roger Griffith Leave a Comment

The recent outbreak of legionnaires’ disease in New York City has brought renewed attention to the inherent risks from legionella bacteria in HVAC and plumbing systems. There are several things that plumbing engineers and designers can do to minimize the risk of legionella colonizing and growing in plumbing systems.

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Thermal Expansion Tanks: Part 3

August 24, 2015 by Roger Griffith Leave a Comment

Selection and Installation of Thermal Expansion Tanks

Using the calculated acceptance volume and total volume for the tank, select an expansion tank from the manufacturer’s data that meets these requirements.

Be aware that in most states, unfired pressure vessels larger than a certain volume must have an ASME stamp. Check your state’s requirement for this limit. If the expansion tank you need is larger than this limitation, it must be constructed in accordance with ASME Section VIII requirements. ASME rated vessels are much higher in cost than non-ASME vessels. Installing multiple smaller tanks, which are below the volume limitation for ASME tanks, is also an option. Most tank manufacturers offer both ASME and non-ASME thermal expansion tanks.

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Thermal Expansion Tanks: Part 2 – Sizing

July 31, 2015 by Roger Griffith Leave a Comment

How To Size Thermal Expansion Tanks For Hot Water Systems

Referring to sizing tables in an expansion tank manufacturer’s catalog is the easiest method, although not the best method, for sizing thermal expansion tanks. Sizing tables provided by the manufacturers, give the tank model number and size based on the water heater’s volume and the system supply pressure. These tables, however, are based on three important assumptions that designers need to be aware of.

First, for most manufacturers, the tables are based on a maximum allowable line pressure of 150 psi. This is the maximum allowable working pressure of most water heaters and thermal expansion tanks. It is also the setting of the water heater relief valve. In other words, the thermal expansion tank, if selected by the tables, could accommodate the thermal expansion up to a system pressure of 150 psi, which is the relieving point for the water heater relief valve. Remember that the purpose of the thermal expansion tank is to avoid the relief valve from relieving. Sizing the thermal expansion tank for a maximum allowable pressure of 135 psi, which is 10% below the relief valve set point, is a better alternative.

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Tankless Water Heaters and Thermal Expansion Tanks

June 21, 2015 by Roger Griffith 4 Comments

Thermal expansion tanks are typically installed in conjunction with storage water heaters, but what are the requirements for tankless water heaters and thermal expansion tanks? This scenario is sometimes overlooked. Let’s look at the specifics.

Section 607.3 of the 2012 International Plumbing Code (IPC) provides the requirements for controlling pressure from thermal expansion. The requirements contained in paragraphs 607. 3 and 607.3.1 do not specifically distinguish between thermal expansion from a storage water heater, a tankless water heater, or other system equipment. Paragraph 607.3.2 does specifically require a device for controlling pressure “when there is a backflow prevention device, check valve or other device installed on the water supply system utilizing storage water heating equipment such that thermal expansion causes an increase in pressure.”

The IPC does not specifically require a thermal expansion tank or other device be installed with a tankless water heater. However, if a storage tank is used in conjunction with a tankless water heater in a closed system, which is sometimes the case with recirculation, then a means of controlling thermal expansion must be provided.

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Thermal Expansion Tanks: Part 1 – The Need

June 20, 2015 by Roger Griffith 2 Comments

When heated, water expands. We know that. When water is heated in a water heater, the water expands, if possible. But what happens when water is heated in a water heater and there is no hot water usage?

This can occur after a period of showering/bathing during peak times followed by a period of no hot water usage. For example, evenings are a time when there is hot water usage for showering followed by a period of no usage while people are sleeping during the night.

During peak usage times, hot water stored in the water heater is distributed to the end users, and cold water fills the water heater. The cold water in the tank is then heated, but when there is no subsequent hot water usage, the heated water has no room for expansion. If there is no place for the expanded water to go, the pressure in the system increases significantly. This leads to one of two possible scenarios:

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