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Measuring temperature at the hot air inlet of a Maytag LP gas clothes dryer (C) Daniel FriedmanDryer & Dryer Vent Temperatures
Safe & Unsafe Temperatures in the Clothes Dryer & its Vent

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Clothes dryer temperatures:

This article on clothes dryer temperatures gives the normal operating temperature at different points inside the clothes dryer appliance and its venting system. We include also unsafe temperatures that might be reached during various dryer faults or conditions and temperatures that could cause a dryer fire.

Page top image: the author [DF] measuring the approximate surface temperature of the hot air inlet of a Maytag LP gas fueled residential clothes dryer. With the dryer heat set to high and the gas burner on and stabilized the temperature was approximately 140 °F (60 °C).

This article series describes good practices for clothes dryer vent installation, lint traps, wall vents, filters, and screens.



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Clothes Dryer & Dryer Vent Temperatures & Fire Hazards

Dryer vent installation, sloppy (C) D FriedmanThis discussion gives the various temperatures found inside of clothes dryers, in and at the clothes dryer tumbler or drum, heater, and in the dryer exhaust vent during both normal safe operation and during unsafe conditions that risk a dryer fire or building fire.

We include a table of the temperatures that occur inside of clothes dryers at different places in the equipment and in its venting system and we describe unsafe dryer operating temperatures.

The two principal contribution made by clothes dryers to building fires are

  1. High operating temperature inside the dryer
  2. Lint accumulation on the dryer blower or elsewhere in the dryer's air path - (Hall 2005), slowing air movement, blocking heat exhaust, causing abnormally-high & unsafe temperatures in the dryer or its venting system.

75-80% of U.S. clothes dryers are electric, 20-25% are fueled by natural gas or LP gas (Bonaccorso 2012), (Energy Star, 2011). The number of clothes dryer fires is distributed approximately in these same percentages. - (CPSC Residential Fire Loss Estimates (Miller, 2012))

The US CPSC estimated an annual rate of 6100 clothes dryer fires, 20 deaths, 190 injuries & property loss of about $80 million between 2008-2010. - CPSC Residential Fire Loss Estimates (Miller, 2012)

The NFPA estimated an annual rate of 16,800 fires, 51 deaths, 380 injuries & property loss of about $236 million - NFPA Annual Fire Loss Report, Home Fires Involving Clothes Dryers and Washing Machines (2010).

High clothes dryer operating temperatures may also contribute to failure of the electric motor operating the tumbler-drum.

Other dryer failures that can lead to high temperatures include the humidity sensor, temperature control system, blower motor/fan, timer control, shutoff control switches.

Table of Clothes Dryer Temperatures

Clothes Dryer Location / Condition Normal Clothes Dryer Temperature Abnormal / Unsafe Clothes Dryer Temperature Comments / Source
Air inlet to the clothes dryer & into dryer heating element

18 °C (64 °F) to 24 °C (75 °F)

 

  Building indoor ambient temperature, conditioned space, comfortable temperatures for sedentary adults3
Air temperature at an electric clothes dryer heater element 120-200°C (250-400 °F)   Varies by dryer heat source such as electric vs gas. (Marks, 2012) cited in (Bonaccorso 2012)1
Air temperature entering the clothes dryer tumbler / drum 80 °C (175 °F)   (Marks, 2012) cited in (Bonaccorso 2012)
Air temperature inside the clothes dryer drum / tumbler 50-57 °C (125-135 °F) > 200 °C (392 °F) Some sources claim 65 °C (150 °F) - informal search 2017/07/17
Air temperatures in the clothes dryer exhaust vent at the dryer 50-57 °C (125-135 °F) > 200 °C (392 °F) (Marks, 2012) cited in (Bonaccorso 2012) 1
Estimated clothes dryer exhaust vent surface temperature at interior surface of exterior wall 45-55 °C (113-130 °F) > 200 °C (392 °F) Author's IR temperature measurements 1,2
Estimated clothes dryer exhaust vent interior surface temperature at exterior wall vent outlet 37-62°C (100-145 °F) > 200 °C (392 °F)

Author's IR temperature measurements 1,2

Dryer vents that pass through hot roof cavities may reach the elevated temperature at the high end of this range.

Pyrolysis temperature range   90 - 150 °C (200-300 °F) PYROLYSIS EXPLAINED (Kim 1994) in (Bonaccorso 2012) warns of pyrolysis hazards at clothes dryers.
Maximum safe temperature inside a clothes dryer <= 200 °C (392 °F) > 200 °C (392 °F) 232°C (450 °F) is the combustion point of paper - in a clothes dryer could initiate a lint or other fire "... no location inside the cabinet can achieve this temperature throughout the seven hours of performance testing" - (Bonaccorso 2012).
       

Notes:

Watch out: potential fire hazards associated with clothes dryers are discussed at CLOTHES DRYER SAFETY CHECKLIST

Watch out: clearance distances between the wall exhaust point and other equipment are explained at CLOTHES DRYER VENT CLEARANCES

1. Scholarly and accurate clothes dryer temperature measurements using direct-contact temperature sensing devices were performed by Bonaccorso (2012) cited at CLOTHES DRYER FIRE RESEARCH.

2. Poughkeepsie NY July 2017- D Friedman (2017) Field measurements of clothes dryer and dryer vent actual on-site measurements conducted by the author [DF] are described at CLOTHES DRYER TEMPERATURE MEASUREMENTS

3. Höppe (1999), Wikipedia (2017)

Gas Clothes Dryer Temperature Measurements

In July 2017, using an Exergen infrared thermometer, I [DF] measured surface temperatures at key locations inside of a gas fueled clothes dryer where I was surprised to find vent temperatures at the building exterior wall were higher than temperatures measured in and close to the clothes dryer itself.

Details are reported at are described at CLOTHES DRYER TEMPERATURE MEASUREMENTS

Clothes Dryer Exhaust Vent Installation, Dryer Temperatures, Dryer Fires Research

Citations mentioned in this article as well as additional clothes dryer operation, temperature, fire hazard research material has moved to CLOTHES DRYER FIRE RESEARCH

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