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HeatShield® Cerfractory Flue Sealant

HeatShield Diagram

HeatShield Diagram

Gaps between chimney flue tiles and missing mortar joints are potentially very dangerous and should be repaired immediately. It used to be that when gaps between tiles or cracks in the flue tiles were discovered, the only way to repair them was to completely remove the flue tiles and replace them with a stainless steel liner. Unfortunately, there was no way to just reach down inside the chimney and re-pack the missing mortar joints or repair the cracked flue tiles … until now. HeatShield® is the answer to repacking deteriorated mortar joints and resurfacing cracked flue tiles – and it can be done at a fraction of the cost of relining your chimney with stainless steel. If you live in the Sacramento area and have a chimney with cracked flue tiles or eroded mortar joints, do not burn fires until repairs have been performed by one of A to Z Chimney Service’s qualified chimney technicians. We can help you determine if HeatShield® cerfractory sealant is a good solution for your chimney.

Are There Hidden Dangers In Your Chimney?

The combustion process that occurs when you light a fire creates noxious gases that can contain creosote, soot, carbon monoxide, and corrosive chemicals. The purpose of your chimney is to safely vent these hazardous flue gases from your home.

Your chimney’s flue tiles are typically sealed with mortar to keep these gases contained within the flue. However, over time, the mixture of rainwater, heat, and chemicals can erode the mortar between the tiles, leaving potentially dangerous gaps or voids.

Cracks in the flue tiles are potentially hazardous, no matter how small. Even hairline cracks can open wide when the flue tile expands as it is subjected to heat. Flue tiles can crack for numerous reasons, but they do so most often as a result of “sudden occurrences”, such as a previous chimney fire, a lightning strike, or a seismic event. Cracks may also be caused by poor workmanship or the ongoing settling of your home.

If not repaired in a timely manner, these defects can begin a process that will further erode the chimney and create a fire hazard. This is because combustible creosote or soot can escape through gaps and cracks in your liner and build up outside the flue. If the creosote were to catch fire in this area of your chimney, serious damage would occur because the fire would no longer be contained within the flue. The gaps and cracks can also cause health risks by allowing poisonous gases to escape into your home and air supply.

HeatShield® Restores The Integrity Of Your Chimney

HeatShield® is a specially formulated “cerfractory” sealant that restores the ability of your chimney’s flue to vent hazardous flue gases from your home. Developed in Europe over 20 years ago, HeatShield®’s cerfractory technology is a hybrid (ceramic/refractory) coating that has been proven to withstand moisture, corrosive flue gases, and temperatures in excess of 2900 degrees Fahrenheit.

It eliminates the dangers in your chimney caused by gaps, cracks, and spalling for years to come. With a 20-year warranty, it has been independently tested to exceed all ASTM (American Society for Testing and Materials) and UL (Underwriters Laboratories –UL2425) standards for chimney repair and resurfacing products.


Enjoy your fireplace or wood stove with confidence this year. Contact A to Z Chimney Services today by emailing or filling out our online appointment form.


Another choice for long-lasting results with chimney relining is stainless steel. Ask us to help determine which one is best for your situation.

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I just wanted to thank you for coming to our rescue the other day. I just purchased a new home and a new washer and dryer to go with it. Understandibly, I was a very confused when my dryer suddenly began taking two or three cycles in order to dry my clothes! To my surprise, the appliance repairman who came out told me that my dryer was just fine, but that my dryer vent needed to be cleaned out! I had never heard of such a thing! Mercifully, he referred me to you guys and everything went better from there.

Your technician discovered that a bird had decided to make its nest in my vent! A lot of effort and tons of nesting material later, my vent was finally unclogged!

Thanks again for your valiant efforts! The guy that came to my house was fantastic and took everything in stride, and didn’t charge me any extra despite the fact that my vent took longer than normal to clean! I’ll be sure to tell everyone where they can get great service having the dryer vent cleaned!

~ Denise Gordon, Roseville, CA
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