Water heater vents generally are of two types; metal, single wall and double wall. Note – some modern high efficiency water heater may have PVC vents.
Metal vents that are too close to wood or combustionable materials may cause the wood to burst into flames. Single wall vents should have a minimum of 6 inches of clearance and double wall, sometimes called a “B” vent, should have 1 inch minimum clearance. The manufacture even stamps this into the vent.
Cut away the wood that’s too close
The fix for this condition is often to cut back any wood that is too close to the vent pipe so that there is proper clearances. Should the vent be a single wall vent, then either cutting back the wood or switching the single wall to a double wall may make this task easier. Occasionally the vent can be moved or shifted over a little, to give it the proper clearance.
Photo’s of two types of vents. Single and double wall metal vents.
Water heater vents have other requirements
In addition to metal vent clearances, there are installation requirements for both metal and PVC vents. These requirements have clearance requirements to windows, the ground and the roof. It is also important that the vent installation to be installed per manufactures recommendations as well as code requirements. Checking the water heaters manufactures website will often provide drawings and requirements. Also, tankless water heaters have specific installation requirements that should be followed.
Consulting a properly qualified plumbing contractor can help provide installation and code requirements.
Who to consult? Plumbers and qualified handymen.
Home owners can generally create the proper clearances for their water heater vents themselves. Plumbers, some carpenters, as well as, qualified handymen can do this type of work quickly and inexpensively.