Rust inside the stove

[poohbear's helper]

In a direct vented gas stove, if someone fails to seal the vent pipes with proper sealant (ours is red and comes in a regular caulk tube) which is designed for the job, the expelled burnt gases leaving the stove through the central part of the pipe will end up instead being sucked into the outer pipe area, which should be carrying fresh uncontaminated air into the burn chamber. Those outgoing fumes, when sucked back inside the stove, will rust out the interior of the stove quite rapidly, like within a year you'll be seeing so much rust inside your main burn chamber you'll be asking what could be wrong here? I became aware of this problem after replacing a rusted out burner in a recently purchased rental house with a brand new burner and coming back after just one heating season to the sight of the new burner completely covered with rust, and the new pilot assembly as well. Getting that direct venting apart to add caulk when someone failed to seal it during the original installation... we found it extremely difficult. We purchased a strap wrench and just struggled with it.... if there's some easy way to disassemble that stuff we'd love to know. Eventually we got it apart, and it was worth the doings. We have another stove in a rental that we must do that for as well this summer, and not looking forward to the job.