Vent Free Gas Space Heaters - Drainless Sinks?

by Jason
(New York)


In the 1996 September/October issue of Home Energy Magazine, a staff researcher from the University of California, Michael Apte, wrote an article comparing unventilated heaters to drainless sinks due to their water vapor and combustion gas emissions. At the time, there were no in-door air pollution standards for residences.


Prior to the article, research discovered that myriad emissions effected homes due to unvented heaters. Emissions such as carbon monoxide, nitrogen dioxide, formaldehyde, respirable suspended particles, and the obvious carbon dioxide were found to be products of gas combustions by the Consumer Product Safety Commission and the U.S. Department of Energy.

Unventilated water vapors can create mildew and fungus once settled on surfaces, which in time can cause further damage to air quality as well as a home. Vented heaters are withdrawn from these troubles because they come with a flue. A flue is a pipe that allows harmful exhausts to flow outdoors so they don’t linger.

In unvented heaters there is a different system meant to deter toxic gases using oxygen depletion sensors (ODS). These sensors were added to stabilize oxygen levels if they sank below 18.5% because standard clean air contains about 20.9% oxygen and more ventilation is necessary when CO2 increases.

Unfortunately, carbon monoxide (CO) can still become a hazard much before the ODS system shuts down the unit. To assist this system, improved burners were created to lower chances of carbon monoxide emissions. However, these heaters were generally more costly despite their inexpensive manufacturing and installation.

According to the article by Mr. Apte, even a small technical manufacturing error had the potential to leave many in harm’s way because an estimated ½ million units were speculated to be sold in 1996. Spokespeople said that temperatures of an area would certainly become “unbearably hot” much before any harmful gases arose, especially if the unit was used often. Unvented heaters pose a problem for many groups of people, such as pregnant women, children, those with asthma, heart disease, any individual already experiencing health issues, and the elderly- who are effected heavily because high temperatures often comfort them at home.
Mr. Apte’s concerning article on unventilated heaters is further expressed through two tables that show pollutant emission rates. The purpose of these tables is to examine how air quality can become compromised while the ODS system remains inactive. The article also states that a heater using approximately 40,000 BTUs per hour throughout the day of a cold season would make the pollutant levels rise beyond the air quality health standards set by the government for workplace air. However, that many BTUs is often a necessity in cold climates.

Mr. Apte also compares vent free heaters’ water vapor emissions to a shower, stating that a shower typically produces around 300 grams of water while in use for nearly an hour. The vapors emitted by the shower generally dissipate quickly due to a window or vent system as regulated by building requirements, but the 400 grams generated per 10,000 BTUs from an unventilated heater will effect the environment negatively if not removed. Michael Apte ends his article by stating, “Putting all this moisture in the living space, unvented gas heaters would truly seem to be like drainless sinks.”

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