VENT-FREE GAS HEATING APPLIANCES FOR HOMES

WHAT EDUCATORS NEED TO KNOW

The Vent-Free Gas Products Alliance has partnered with the Home Safety Council (HSC) to provide fire and life safety educators with important facts about supplemental vent-free home heating appliances. 

Used in homes since the early 1980s, more than 17 million vent-free gas heaters are estimated to be in use in U.S. homes today.  All major national building codes and every state except California permit the sale and installation of the appliances for residential use. 

It’s likely that residents of your community have these heaters in their homes. If you aren’t fully familiar with the vent-free technology, this fact sheet can provide useful information. 

How is vent-free technology different?

Vent-free heating appliances are similar to other space heaters used in the home – they provide a supplemental heat source, such as fireplaces, gas stoves and heaters, and log sets.  The difference is that vent-free gas appliances are designed to be installed and operated without a chimney, flue or vent.

They can be powered by natural gas or propane. The products range from 5,000 to 40,000 Btu. Bedroom products, which include fireplaces, range from 8,000-10,000 Btu units. Bathroom units are 6,000 Btu.

Vent-free safety

Supplemental Heat Source:  Vent-free gas heating appliances are designed and intended for supplemental use only.  However, in the case of a power outage, these units may be used to heat the home.  In most areas of the country, wall-hung, permanently installed vent-free supplemental heaters that do not exceed the required Btu limit are permitted in bedrooms and bathrooms, including 10,000 Btu fireplaces with a mantle and screen. 

Certification:  The American National Standards Institute (ANSI) maintains the voluntary standard Z21.11.2 for vent-free gas heating appliances.  The ANSI Standard defines the safety, performance and construction requirements for the products.

Safety Sensor:  Every vent-free heating unit sold in the U.S. must have a tamper-resistant, precision-engineered oxygen detection safety sensor (ODS).  Just as a circuit breaker monitors electrical current and shuts off the flow if it gets too high, the ODS works to automatically shut off the vent-free gas appliance should the optimal oxygen level near the unit begin to drop.  The ODS shut-off point minimum is defined by ANSI Z21.11.2.

Pressure regulator:  Certified vent-free gas appliances are fitted with an internal, non-adjustable pressure regulator that prevents over-firing in the event of increased gas pressure.

Installation:  Vent-free gas appliances must be installed by a licensed installer, in accordance with local code requirements and properly sized for location, with appropriate clearance from combustibles.

Additional Safety Features:  All vent-free gas appliances are permanently installed and have defined distances to combustible surfaces. Safety grills are installed on heaters, and fire screens and hoods are standard for gas logs and fireplaces.

Safety Record

Indoor Air Quality:  Certified vent-free gas appliances meet emission requirements of nationally recognized guidelines for indoor air quality.

IMPORTANT: There is no need to open a window to ventilate a vent-free gas heating appliance. In 1999, language recommending an open window for ventilation was removed from the ANSI standard.

According to the U.S. Consumer Product Safety Commission (CPSC), there is no record of a documented incident in CPSC’s In-Depth Investigation Database of fatal carbon monoxide (CO) poisoning associated with an ODS-equipped vent-free gas heating product.

Vent-free Gas Appliance Safety Recommendations

Supplemental Heating:  Vent-free gas appliances should be used as supplemental space heaters. They should not be used as the primary source of heat, except for a limited period of time during a power outage.

Open Flame: Safety screens should be used in front of appliances with open flames.

Safety Standard Certification: Before purchasing vent-free gas products, confirm the product is certified compliant with ANSI Z21.11.2.  Check product packaging for the certification symbol of a nationally recognized testing laboratory.

Follow safe-use and maintenance practices for all types of home heating equipment. Read these safety guides from the Home Safety Council to learn more:

Home Heating Safety

Home Fire Safety

Additional vent-free gas product resources:

Safety features

Indoor air quality research

Vent-Free Gas Products Alliance Slide Presentation

The Vent-Free Gas Products Alliance is a coalition of members of the Vent-Free Gas Products Division of GAMA, a national trade association representing appliance and equipment manufacturers.