What is the recommended height of the flue coming out of the chimney?
There is a screen over this chimney, for birds.

Usually 2-4 inches above the chimney cap (crown)

Are you referring to the “liner,” or an exhaust system of other sorts? That looks like an unlined masonry chimney. Can’t really tell from your photo.

Not sure if it is lined. Was unable to see from the roof. Furnace and watertank vent into this.

They don’t need to extend out of the chimney. . .

Would you recommend rain cap? Brain in post#2 says 2 to 4 inches?

I always recommend a rain/weather cap. Even here in sunny CA.

When I encounter a chimney that is not accessible from the roof (Like this one) I take a picture at the access door in the basement. (If there is one and if I can open the door) When I get home I can enlarge the photo to try to determine if there is a flue.

The chimney pictured appears to have been rebuilt at the top. They should of extended the flue so they can install a proper cap.

If higher efficiency appliances are venting up this chimney it will deteriorate again.

This chimney may require a liner & cap depending on what type of furnace is installed. This would be beyond our scope of an inspection.

I just wouldn’t want to be responsible if there was an unlined chimney.

That was for a clay tile flue liner to extend above the crown (called “chimney cap” in Canuck land); a rain cap would be at least 6-10 inches high above the flue top to allow for easy exit of exhaust gases.

Here’s a representation of a good masonry chimney:


I noticed this US org was calling the crown a chimney cap also.