In general, it is not recommended for a water heater and a dryer to share the same vent. Both appliances produce exhaust gases that need to be vented to the outside for safety reasons. Combining their vents can create several potential hazards, including:
Fire hazard: Dryers produce lint, which is highly flammable. If the lint mixes with the hot exhaust gases from the water heater, it can create a fire hazard.
Carbon monoxide poisoning: Gas water heaters produce carbon monoxide (CO), a colorless and odorless gas that can be deadly in high concentrations. If the dryer vent is blocked or restricted, it could cause the CO to back up into the living space, putting occupants at risk of carbon monoxide poisoning.
Poor performance: Sharing a vent can lead to reduced efficiency and performance of both appliances, as the exhaust gases from one can interfere with the proper operation of the other.
Building code violations: Many building codes and regulations prohibit the sharing of vents between appliances like water heaters and dryers due to safety concerns.
To ensure safety and proper functioning of both the water heater and dryer, it is essential to have separate, dedicated vents for each appliance. If you're unsure about the setup in your home or need to make changes, it is advisable to consult a professional HVAC technician or a licensed plumber to assess your specific situation and provide appropriate recommendations. Always prioritize safety when dealing with any gas appliances and their venting systems.