Chimney flue height?

This chimney appears to have been rebuilt and a new crown installed. The flue is now lower than the crown. I seem to recall that the flue needs to be higher than the crown but cannot find any reference to this. This chimney is for a gas boiler and water heater. Any help with a reference will be appreciated.

Up here in Canada the recommended height is 6" above the crown. Not sure the exact location in the text though.

Good info here.

If connected to gas fired appliances should it not also have a metal liner?

It’s a nice funnel for rainwater as well. Would love to see what happens during a torrential rain.

Ugly swimming pool…oh wait that’s a Chimney ?

2" minimum as recommended by

Had no idea re the height but a rain hat and spark arrestor couldn’t hurt!

In Ontario it’s 2" min. - 4" max. height above the chimney cap.
O.B.C. Section

Yes, metal liner for gas appliances. Over time the acids produced by gas appliances tend to eat away at the inside of a masonry chimney, which can compromise the safety of your family and home.