We had professionally installed kitchen exhaust vent, venting outside. We had 300cfm and we were having smell issue in the house even after venting outside. We replaced the fan with 900 cfm and still having issue with smell in the house. Our new fan will run for few minutes and then shuts off. We called the guy back who installed our 900 cfm fan and he said there is leaking from the pipe that was installed for venting out.
What kind of pipe should we use? Why we are still having smell in the house when we cook even with 900 cfm fan?