Thread: Masonry chimney damage

Four years ago the heating unit was replaced with a high efficient system in this 35 year old single family home. This upgrade left the water heater orphaned. As you can see the local building official approved this installation. Could the damage to the chimney structure and flue happened within the past 4 years?
Is there anything in the NFPA or Flue gas code that does not permit this type of installation?

Originally Posted by Richard Roshak

Four years ago the heating unit was replaced with a high efficient system in this 35 year old single family home. This upgrade left the water heater orphaned. As you can see the local building official approved this installation. Could the damage to the chimney structure and flue happened within the past 4 years?
Is there anything in the NFPA or Flue gas code that does not permit this type of installation?

I think most of the wear was likely already there or unrelated to the lack of a liner. If the flue was less than 7" by 7" (49 square inches) it likely did not require a liner - if it is more than that size it would have been required. It likely would have been best to reline 4 years ago when the furnace was done. Now with the extreme flaking at the clay flue and the worn, poorly installed crown it would be best to reline and replace the crown.

Originally Posted by Richard Roshak

Four years ago the heating unit was replaced with a high efficient system in this 35 year old single family home. This upgrade left the water heater orphaned. As you can see the local building official approved this installation. Could the damage to the chimney structure and flue happened within the past 4 years?
Is there anything in the NFPA or Flue gas code that does not permit this type of installation?

The codes will allow the interior of the flue to be up to 7 times the area of the outlet of the gas appliance. It looks like there is a condensation problem in this flue causing the tile liner to spall. When the flue is larger than the outlet of the appliance it has a greater residence time and ability to cool and condense. I would say that the orphaned water heater is easily capable of creating this type of damage over a period of 4 years. It often takes much less time. The clear risk here is in having the flakes obstruct the flue and prevent the exhaust from venting out of the home.

Ashley Eldridge
CSIA Director of Education
Chimney Safety Institute of America (CSIA) | Plainfield, IN

That chimney has been in bad shape for many years, who know how long it has been in that condition. The fact that the AHJ approved it is really a moot point, they chimney liner and crown are toast.