Chimney efflorescence tells a bigger story

Home Inspector with Ryan and Son Chimneys Contractors LLC

Here in the northeast we have very unique venting situations and challenges for our heating appliances.  How many times have you seen a path of efflorescence on a chimney similar to the pattern on the right hand side of the chimney? 

This is actually an indication of a serious problem with the venting of the heating appliances.  When you can visually make out the path of an internal flue on an external chimney, look deeper.  This flue is serving 2 gas fired appliances; a fan assisted 86% efficient furnace and a 40,000 BTU Water heater.  Both appliances are creating interior flue condensation when they operated separately.

The most common repair for this issue is a PROPER chimney liner.  Proper meaning properly sized, insulated (although not required, insulating a heating appliance chimney liner on an exterior chimney is highly recommended)

Once the source of the interior water issue is resolved, the efflorescence should be removed from the chimney and the chimney should be treated with a water repellent.Chimney efflorescence

Posted by

Bill Ryan

Ryan and Son Chimneys Contractors

(973) 398-3978

Fireplace Investigation Research and Education Certified Fireplace and Chimney Inspector # FP-089

International Association of Fireplace and Inspectors Certified Professional Chimney Inspector # CPI-002

National Fireplace Institute Certifed Specialist in Wood and Gas

Residential and Commercial Structures ICC/NJ Certified Building Inspector (license pending)


Comments (3)

Harry F. D'Elia III
RentVest - Phoenix, AZ
Investor , Mentor, GRI, Radio, CIPS, REOs, ABR

Thanks for sharing this pertinent information with us this morning

Jun 03, 2010 02:05 AM
Katherine Fornale

Thanks, I'm always looking to learn new things.

Jun 03, 2010 02:16 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

William, good post about the problems with multiple appliances venting into the same flue.  I think it is bad idea because the flue will always be too big for either one----and only correct when they are both running if its sided for both.  I know it is allowed---but it would not be on my planet.

Jun 03, 2010 08:31 AM