🚨 Critical Safety Notice
Many HVAC contractors install new gas furnaces without relining the chimney. This is a code violation in most Maryland jurisdictions and creates a serious carbon monoxide risk. Always confirm your chimney is properly relined before your new furnace is put into service.
Switching from oil to natural gas is a popular choice for Baltimore homeowners looking to increase efficiency and lower their energy costs. However, many homeowners—and some HVAC contractors—overlook the most critical part of this conversion: the chimney. If you don't resize your flue for gas, you're creating a serious safety and structural hazard.
The Fundamental Difference Between Oil & Gas Exhaust
Oil Furnace Exhaust
- ▸ High exhaust temperature (350–500°F)
- ▸ Low moisture content
- ▸ Rises quickly through the flue
- ▸ Requires large diameter flue
Gas Furnace Exhaust
- ▸ Cool exhaust (80–140°F for high-efficiency)
- ▸ High water vapor & acidity
- ▸ Rises slowly — lingers in flue
- ▸ Requires smaller, lined flue
“Every oil-to-gas conversion we get called for repair—we ask the same question: did your HVAC contractor reline the flue? Nine times out of ten, the answer is no.” — Stanley Mattatall, CSIA Certified Master Sweep
Carbon Monoxide Risk
An oversized chimney flue creates a “lazy draft.” If not properly sized, the appliance may fail to exhaust gases entirely—pushing deadly CO back into your basement or living spaces.
The Liner Solution
A UL-listed stainless steel liner sized precisely for your new appliance's BTU output creates a dedicated, safely sized corridor that prevents condensation and ensures a perfect draft.
Changing Your Heating System?
Ensure your oil-to-gas conversion is safe and code-compliant. We work directly with HVAC installers to provide professional chimney relining during the switch—often same week.
