Improving the Performance of Wall Furnaces in California Homes

Institute of Gas Technology dba GTI Energy


Des Plaines, IL

Recipient Location



Amount Spent



Project Status

Project Result

The recipient completed the first
baseline heating season in the demonstration homes in Southern California. The baseline report showed low usage of gas and low levels of NOx, CO, PM2.5 and PM10. The team installed submeters in the retrofit wall furnaces to allow for remote monitoring of gas use and to quantify/compare efficiencies. The double-sided wall furnace was installed in Oakland and testing will start in October 2021. The self-powered version of the gravity wall furnace will be tested starting in October 2021. The recipient is testing the old furnaces from Southern California in the laboratory.

The Issue

Property owners bear the cost of energy upgrades, and tenants bear monthly energy costs. Heating equipment purchases are primarily driven by low equipment first costs. Therefore, low-cost, ductless natural-gas powered gravity wall furnaces and floor furnaces have commonly occurred to heat small apartments, and even single-family homes. These devices typically have standing pilot lights and lack fans, requiring only a gas line and an exhaust vent. They are atmospherically vented, drawing in combustion air from conditioned space and expelling combustion by-products through the exhaust. These units are inefficient and could pose indoor air quality issues.

Project Innovation

This project will determine the prevalence of wall and floor furnaces in California homes, and characterize baseline emissions and energy efficiency. The project develops and demonstrates retrofit packages for wall furnaces in existing homes, with payback on incremental costs that is within the life of the technology. The research includes market outreach and technology transfer with property owners, installers, manufacturers, and utilities to accelerate the adoption of more efficient wall furnace retrofit options in California.

Project Benefits

This project hopes to overcome barriers for wall-furnace retrofits by demonstrating two different solutions that increase efficiency while reducing installation costs: The solutions include: 1) A self-powered drop-in replacement for existing unpowered gravity furnaces, offering improved efficiency up to 75-80% AFUE, without requiring electrical service, and 2) A direct vent solution with an efficiency of up to 90% AFUE, but requiring electrical service and building modifications.

Lower Costs


A self-powered drop-in replacement for existing unpowered gravity furnaces, will offer improved efficiency up to 75-80% AFUE, without requiring electrical service. The increased efficiency will reduce natural gas use and costs.

Key Project Members

Project Member

Rob Kaminsky




Frontier Energy, Inc.


Match Partners


Southern California Gas Company (SoCalGas)


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