Scalding Issues Associated with Low Flow Fixtures · Copyright 2010: Ron George, Ron George Design...

Copyright 2010: Ron George, Ron George Design & Consulting Services

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By: Ron George, CIPE, CPDRon George Design & Consulting Services3525 N. Dixie HwyMonroe, MI 48162(734) 755-1908 cell(734) 322-0225 OfficeWeb Site: www.rongeorgedesign.com

Scalding Issues Associated Scalding Issues Associated with Low Flow Fixtureswith Low Flow FixturesPresented to:Water EC ConferenceNewport Beach, CA March 30, 2009And ASME/CSA Committee on Low Flow Shower Heads April 22, 2009

Low Flow Showersand their effect on

Temperature Control


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Non-HouseholdUsesOutdoorHouseholdUsesToilet Use

Drinking,Bathing, Etc..

Facts About Water Use in the United States

Source: US Geological Survey, Environmental Protection Agency

The 1992 Energy Policy Act is a federal law that was enacted to save water and energy by mandating low flow toilets, showers and lavatories.

Non-Residential Water Use: Agricultural, Industrial, Commercial, Etc. = 87%

8%

Residential Irrigation = 5%

Indoor Household Use = 8%

Toilet = 2.4%

Drinking, Bathing, Washing = 5.6%

8% of all Water Use is “Residential”

87%

5%5.6%2.4%


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Health and Safety Issues– Plumbing Engineering Issues:

• Engineers and Design Professionals are concerned about product performance, user comfort/satisfaction and Safety Issues.

Flow vs Temperature control

New Low Flow Products:


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Thermal Shock & Scalding ConcernsThere is a Major Concern in Older Homes with Two-Handled Non-compensating Shower Controls.

• Thermal shock and scalding is a health and safety issue related to the restriction of flow at shower heads with non-compensating type shower valves. This is a matter of Physics.

• No manufacturer can build a low-flow shower head that will not be susceptible to thermal shock and scalding if it is connected to a two-handled or non-compensating shower valve.

• Validation needed through testing with older style shower valves.• Currently ALL WaterSense and EPA testing I have inquired about is

done with newer code compliant installations the results of the testing are skewed with respect to the risk of thermal shock andscalding.


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Thermal Shock - Definition

• Thermal Shock occurs when there is a pressure or temperature disturbance in the piping system that will cause a sudden change in the shower temperature. The sudden change in the shower temperature can cause a slip and fall injury that an lead to broken bones or a head injury from a fall. Sometimes the bather will grab the temperature controls on the way down and it can lead to a scalding incident.


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Scalding - Definition

• Scalding can occur when the skin is exposed to temperatures in excess of 120 degrees Fahrenheit. Scalding can occur in varying degrees based on the temperature of the water and the exposure time.


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Temperature/Time Burn Chart

Temp. in Deg. F111 F =113 F =116 F =118 F =120 F = 124 F = 131 F =140 F =151 F =

Time for 2nd deg. burn270 min’s.120 min’s.20 min’s.15 min’s.8 min’s.2 min’s. 17 seconds3 seconds Instant

(Source: Report prepared by Dr. Moritz and Dr. Henriques at Harvard Medical School in the 1940s for adult males. Children and elderly can receive burns in less time because their skin is thinner.)

Time for 3rd Deg. burn300 min’s.180 min’s.45 min’s.20 min’s.10 min’s.4.2 min’s.30 seconds5 seconds2 Seconds


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Definition:

• Non-Compensating Shower Control Valve– A shower valve that does not compensate for changes in pressure or temperature. This would include: Two-handled shower valves and older style Single-handle shower valves without a pressure balancing/compensating component or a thermostatic compensating component. It is estimated that over 50 percent of all existing homes have non-compensating shower valves.


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Two-Handled Shower Valves do not prevent:

Scalding or Thermal Shock

This style of shower control is probably the most common shower valve installed in older homes in the US. (About 50%) Two-handled shower valves do not compensate for changes in incoming pressure or temperature as required by the model plumbing codes. These types of valves were generally installed prior to when codes required anti-scald valves for new construction.

It is estimated that close to 50% of all existing showers have two-handle non-compensating shower controls.


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Two-Handled Shower Valves do not prevent:

Scalding or Thermal Shock

When an existing shower head is replaced with a low flow shower head the low flow shower head creates a flow restriction in the shower arm. Pressure disturbances in the system become the path of least resistance when another nearby fixture is opened.

Flow Restrictor Type Shower Head

Flow Restrictor

When a near-by CW fixture is used HW will crossover through the valve and flow to the path of least resistance.


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In many Areas Water Utilities and Conservation Programs are handing out FREE Low-Flow shower heads.

• This practice is EXTREMELY DANGEROUS and exposes the entity to a liability because the low flow shower heads could lead to scalding and thermal shockinjuries if they are installed in older systems without compensating type shower valves.

• Warning labels and training are needed!


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Low Flow Shower Head Issues:There is a great need for research to determine a minimally acceptable shower flow rate that will still Provide user comfort and address several issues, including the

following:

1. Water droplet size - spray mist Legionellae Issues Small water droplet size allows inhalation of water mist with Legionellae bacteria. This also contributes to high moisture in bathrooms and can increase the possibility of mold issues.Consider a fan test to check for small water droplets.

2. Force Some models of low flow shower heads have very little force or rinsing ability.

3. Ineffective Anti-Scald Devices with LF Showerheads Showerheads @ 1.5 GPM and lower still have a full spray pattern when an ASSE 1062 Flow Reduction device trips to reduce the flow of water.Testing I have conducted shows the shower head still has a full spray pattern in lieu of the trickle when an ASSE 1062 anti-scald device is installed on the shower arm.

• Noise Aspirating type showers tend to be loud as the draw water into the stream of water it creates a whistling/roaring sound and it also create water mist inhalation hazards

• Wind chill factor – Higher usage temperaturesAspirating type shower entrain air and water and create a wind chill effect in the shower. This causes the bather to use a higher temperature setting than they would normally use. Entrained air and evaporative cooling and wind chill effect causing higher usage temperatures (hot heads and cold feet).


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Low Flow Shower Head Issues:6. Temperature from top to bottom of shower area w/ fine droplets

Preliminary testing shows fine mist shower sprays cause higher temperature settings. There is a very hot temperature coming out of the shower head and because of evaporative cooling of the small droplets the water feels very cold by the time it is near the bathers feet.

7. Additional Time Required in the ShowerLow flow shower heads cause longer showering times. Time = $ Consider testing to compare the length of showering time with various flow rates and shower head types. Consider a test of a 1 GPM shower head showering time vs a 2.5 GPM showering time.

8. Time vs Temperature control delays With lower flow shower heads and standard ½ inch risers there is a several second delay from the time you adjust the temperature control until the time the adjusted temperature water flows out of the low flow shower head. This delay can lead to over correction and thermal shock and/or scalding issues.

9. User Satisfactionshampoo rinse, time in shower

– Low flow shower heads cause longer showering times. Time = $


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1. Scalding and thermal shock – Scalding and/or thermal shock can occur when low flow or “green” products are mismatched.

Low flow with non-compensating shower valve example:

»A low-flow shower head installed with a shower valve that is non-compensating will not safely control the temperature as flows and pressures change.

Low Flow Shower Heads Health and Safety Issues:


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Two-Handle Faucet or Non-Compensating Shower Valve Flow Dynamics

Flow

Mixed Flow to shower head Flow Restrictor (Resistence)

Nearby CW Fixture Flowing

Non-Compensating Two Handle Faucet

Hot Water Crossover to Cold Water Pipe (Path of Least Resistance)

Nearby CW Fixture

Pressure Disturbance

Normal Flow

Non-Compensating Two Handle Faucet

Copyright 2010: Ron George, Ron George Design & Consulting Services16

A two-handled non-safety shower valve

Flow Restrictor

Closed ClosedClosed

No Flow

Shower Head


Flow Restrictor

Closed ClosedOpened

HW Flow only can produce scald burns

Dangerous Hot Water TemperatureA two-handled non-

safety shower valve.

Shower Head


Flow Restrictor

Closed ClosedClosed

No Flow hot water in pipes cooling off

Shower Head

105 Deg. F Mixed Water TemperatureA two-handled non-



Flow Restrictor

Opened ClosedClosed

CW Flow

Shower Head

40 Deg. F CW TemperatureA two-handled non-



Opened ClosedOpened

Flow Restrictor

Mixed Flow

Shower Head

Turbulent flow mixes water streams

105 Deg. F Mixed Water TemperatureA two-handled non-



Opened OpenedOpened

Flow Restrictor

Mixed Flow With Pressure Disturbance Nearby CW Valve is Opened. Crossflow from no check valve on shower valve supplies

Shower HeadIllustration of A non-safety shower valve with crossover flow and a pressure disturbance

Water Flowing

Dangerous Hot Water Temperature


Open ClosedOpen

Flow Restrictor

Animation of A non-compensating faucet with crossover flow and a pressure disturbance

Mixed Flow Returned to Normal When Nearby CW Valve is Closed


ASSE Single-Handle Pressure Balancing Shower Valves


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Pressure Balancing ValveTW

CW HW

Pressure balancing piston moves back and forth with changes in pressure to maintain a constant mixed water ratio/temperature at the outlet.


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CW HW


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CW HW


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CW HW


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CW HW


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CW HW


30


CW HW

If the incoming water temperature changes this type of valve does not have the ability to sense temperature and compensate for incoming water temperature changes


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The Thermostatic Shower ValvesTwo kinds of actuators

2. Liquid Parafin Wax Filled Capsule Principle

This Design is like a clock spring. It has poor torque & it is susceptible to sticking because of scale & sediment build-up on the coil and shuttle

Only a few pounds of force to move a mixing valve shuttle.

Hundreds of pounds of force to move a mixing valve shuttle.

1. Bi-Metal Principle

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Thermostatic Valves with Parafin Wax offer swift reaction and a powerful stroke

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Scald Burns

• Scald Burns are extremely painful and life altering injuries!

• We must take every precaution to test for the potential to increase the risk of thermal shock and scalding. If there is any possibility of an increased risk we must warn consumers and building owner of the potential increased risk of scalding.

• Warnings must be included on products, packaging and in installation and maintenance literature with low flow showerheads (Below 2.5 GPM)

• Ignoring the problem and Increasing the risk of thermal shock and scalding should not be allowed.


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Shower Flow Study Testing Flow Rate vs Temperature ControlShows need for industry warning.

• A Recent Report at an ASME low flow Showerhead task force meeting in Reno NV showed: As Flows through shower control valves were reduced, the ability of the shower valve to control the temperature to ASSE limits diminished. ASSE standards are proposed for revision to address this issue. Warnings should berequired if the shower head and shower valve are not matched in flows or supplied by the same manufacturer.

1 GPM2.5 GPM AT 1 GPM MIXING VALVE FAILS ASSE TEMP CONTROL

AT 2.5 GPM MIXING VALVE PASSES ASSE TEMP CONTROL


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WARNING Labels and Education are neededWARNING! Shower valves may not work properly when low flow showerheads (restricting water flow below 2.5 gpm) are installed. Installing low flow showerheads where compensating shower valves or conventional, non-compensating shower valves are installed will increase the risk of scalding or other types of injuries, such as slips and falls due to thermal shock when the plumbing system experiences pressure changes. Make sure the low flow showerhead you wish to install is installed with a shower valve that has been designed, tested and verified to function safely at the reduced flow rate. If in doubt, consult the manufacturer of the valve before installing a low flow showerhead.

1 Thermostatic compensating valves are designed to keep bathing water temperatures in the shower fairly constant when other appliances, such as a washing machine or toilet, are in use and when the hot or cold water supply pressures change or the bathing water outlet temperature changes. The response of this type of mechanism is different to that of a pressure balance compensating valve see Note2.

2 Pressure balance compensating valves are designed to keep bathing water temperature in the shower fairly constant when other appliances, such as a washing machine or toilet, are in use and when the hot or cold water supply pressures change.

3 Conventional, non-compensating valves are completely dependent on the user to adjust the temperature at all times by changing the adjustment these types of controls are not recommended with low flow or flow restricted shower heads, because the possibility of scalding and thermal shock increases with the flow restriction.


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WARNING!Conventional, non-compensating valves are completely dependent on the user to adjust the temperature at all times by changing the adjustment. These types of controls are NOT recommended with low flow or flow restricted shower heads, because the possibility of scalding and thermal shock increases with the flow restriction.


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Local Jurisdictions Ignore Safety

• Local Water Jurisdictions that Pass Water Efficiency ordinances and distribute shower heads without warnings about non-compensating shower valves are putting themselves at risk. (Example: Miami Dade County Water Conservation Ordinance)

• Some Water Utilities are Passing out 1.5 GPM flow restrictors and shower heads and are unwittingly creating dangerous systems.


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The ““Stacking EffectStacking Effect”” in Un-circulated Water Heaters

T

Up to 165 FUp to 165 F

HOT WATER RISES TO HOT WATER RISES TO THE TOP OF AN THE TOP OF AN UNCIRCULATED TANKUNCIRCULATED TANKDURING PERIODS OF DURING PERIODS OF NONNON--USE. USE.

COLD WATER IS MORE COLD WATER IS MORE DENSE AND STAYS AT DENSE AND STAYS AT THE BOTTOM OF THE THE BOTTOM OF THE TANK.TANK.

THERE CAN BE A SIGINIFICANT DIFFERENCE IN TEMPERATURE FROM THE TOP OF THE TANK TO THE BOTTOM.

THE TOP PORTION OF THE TANK CAN BE EXTREMELY HOT.

THE THERMOSTAT CAN VARY AS MUCH AS 15-18 DEGREES PLUS OR MINUS THE SET POINT

THE BOTTOM PORTION IS NOT HOT ENOUGH TO BE A USEABLE TEMPERATURE.

3434--858500 FF

143 F = OFF143 F = OFF125 F Set Pt 125 F Set Pt 107 F = ON107 F = ON

165 F HW out

T-Stat Set at 125 FGraphic By: Ron George, President, Ron George Design & Consulting Services. www.rongeorgedesign.com


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The ““Stacking EffectStacking Effect”” in Un-circulated Water Heaters

T

up to 155 Fup to 155 F



THERE CAN BE A SIGINIFICANT DIFFERENCE IN TEMPERATURE FROM THE TOP OF THE TANK TO THE BOTTOM.




3434--858500 FF


T-Stat Set at 120 FGraphic By: Ron George, President, Ron George Design & Consulting Services. www.rongeorgedesign.com

155 F HW out


Typical HW System Temperature Fluctuations

Flow Test By: Ron George, CPD, President Ron George Design & Consulting Services

Circulated system with a 24 Degree F temperature swing.

Un-circulated Hot water tanks will typically see system temperatures with a wider temperature swing

Flow Rate = 2.4 GPM

120 Degree F Temp setting

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Turning Down the Thermostat Setting on a Water Heater Will

NOT Prevent Scalding!• Most Plumbing Codes will not allow the

thermostat on the water heater to be used as the final temperature control on a domestic hot water system to prevent scalding. Because the System temperatures fluctuate widely as shown in the previous slide.

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How Do We Control the Temperature Swings?Use ASSE 1017 Thermostatic Mixing Valves at the Water Heater!

120 F34 - 85 F

T

143 F143 F toto 163 F163 F


3434--858500 FF



THERE CAN BE 120 DEGREE F DIFFERENCE IN TEMPERATURE FROM THE TOP OF THE TANK TO THE BOTTOM.




ASSE 1017 Therm. Mixing Valve

143 -163 F HW

Graphic By: Ron George, President, Ron George Design & Consulting Services. www.rongeorgedesign.com


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120 F

34 - 85 F

T

125 F125 F toto 155 F155 F


107107--11011000 FF

ASSE 1017 Thermostatic Mixing Valve

125 -155 F HW

HW CIRC PUMP



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CW

ASSE 1017/ CSA B125Thermostatic Mixing Valve

T

SHOWER VA.ASSE 1016 / CSA B125

TAFR VA.ASSE 1062

TW 120 F

40 F

155 F

120 F



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The Device installed here or in tub spout shuts-off the flow of water to a drip when the temperature exceeds 115 to 117 Degrees F (46C to 47C)

Available at: http://www.cashacme.com/prod_thermostatics_HG_TAFR.phpor www.pppinc.net

A cheap solution for non-compensating valves.

Temperature Actuated Flow Reduction Valve (TAFR) ASSE-1062


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The Device installed here or in a tub spout shuts-off the flow of water to a drip when the temperature exceeds 115 to 117 Degrees F (46C to 47C)

Available at: http://www.cashacme.com/prod_thermostatics_HG_TAFR.phpor www.pppinc.net

A cheap solution for non-compensating shower valves.

Temperature Actuated Flow Reduction Valve (TAFR) ASSE-1062


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Some Ultra Low Flow shower heads still have a full spray pattern when the ASSE 1062 Device activates and reduces the flow to approx 0.5 GPM.

A cheap solution for non-compensating shower valves.Temperature Actuated Flow Reduction Valve (TAFR)

ASSE-1062

CAUTION:CAUTION:

Ultra Low Flow (ULF) Shower Heads Can Ultra Low Flow (ULF) Shower Heads Can Cause Safety Devices to Not Work Properly!Cause Safety Devices to Not Work Properly!

ASSE 1062 Temperature Actuated Flow Reduction Device

0.5 GPM ULF Shower Head


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Plumbing Engineers recommend 135 ºF - 140ºF storage temperatures

• 140ºF Water Storage Temperatures Kill Bacteria and Pathogens in the hot water such as Legionellae.

140 Deg F Storage Temp


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Legionellae and Temperature• Below 68°F Legionellae can survive but are dormant• Legionellae growth range (68°F - 122°F)• Ideal growth range (95°F - 115°F)• Above 122°F Legionellae can survive but do not

multiply• At 130°F Legionellae die within 5 to 6 hours• At 140°F Legionellae die within 32 minutes• At 150°F Legionellae die within 2 minutes• Disinfection range (158°F - 176°F)


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Why use Thermostatic Mixing Valves?

• Safety: Accurately and Safely deliver water to points of use when the water storage temperatures have been increased to:A) Store Hot water above 135 degrees F to

Eliminate Legionellae growth in hot water tanks.

B) Prevent flue gases from condensing in gas fired water heaters that are not designed for condensing operation.


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We need to develop water conservation products and programs to reduce the water demands for future generations. Manufacturers, engineers, Inspectors and plumbers need to develop water and energy conservation products that not only address water conservation, but also address:- Safety (no scalding or thermal shock)- System performance (Proper shower flow and drain-line carry)- User satisfaction. (Enough flow from fixtures to satisfy the users without wasting their time.)

Green Initiatives: LEED and WaterSense


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Quotes“Protection of the Public’s Health and Safety is Non-

negotiable!”Source: Undersecretary, Department of Environment and Natural Resources, (DENR) Brigadier General, Francisco Bravo (Philippines)Former President, Philippine Society of Sanitary Engineers

“Water Conservation is important, but not more important than bather safety!”Ron George, CPD, PresidentRon George Design & Consulting Serviceswww.rongeorgedesign.com


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Non-HouseholdUsesOutdoorHouseholdUsesToilet Use

Drinking,Bathing, Etc..

Source: US Geological Survey, Environmental Protection Agency


8%

Residential Irrigation = 5%

Indoor Household Use = 8%

Toilet = 2.4%

Drinking, Bathing, Washing = 5.6%

8% of Water Use is Residential

87%

5%5.6%2.4%


Keep focus on where the real potential is for water savings.

Summary: Facts About Water Use in the United States


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By: Ron George, CIPE, CPDRon George Design & Consulting Services3525 N. Dixie HwyMonroe, MI 48162(734) 755-1908 cell(734) 322-0225 OfficeWeb Site: www.rongeorgedesign.com

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Graphics By: Ron George, President, Ron George Design & Consulting Services. www.rongeorgedesign.com

Scalding Issues Associated with Low Flow Fixtures · Copyright 2010: Ron George, Ron George Design...

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