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Thermocrete Ceramic Flue Sealant FAQ's
1. My chimney needs repairing; can any chimney professional use Thermocrete?
Thermocrete Ceramic Flue Sealant can only be installed by a factory trained technician and in California, must have a Masonry License (C29) Classfication http://www.cslb.ca.gov/GeneralInformation/Library/LicensingClassifications/ . Each applicant is thoroughly screened prior to being accepted into our training program. Each and every company brings their team experienced chimney professionals to our facility for three days of intensive training on specialized equipment. They each receive certification assuring you that they know when and where Thermocrete is an applicable restoration technique.
2. Can Thermocrete repair a chimney-fire damaged liner tile? When would CFS be appropriate for this?
CFS does repair heat-damaged clay tile. It fills cracks, binds tile together, closes eroded tile joints, and provides a heat-diffusing barrier that renders the total liner better than it was when it was first installed. Tests show that a CFS-repaired broken tile liner is gas-tight, remains intact during normal (sub-1200ºF) use, and is 99% less likely to crack or re-crack during elevated chimney-fire temperatures of 1200º-2100ºF. CFS will fill normal masonry joints, but for fire-damaged tile repair, we require that only liners with no more than 1/8”cracks be candidates for CFS. If tiles are broken apart, loose, or missing, you can’t use CFS. If tiles have holes in them or gaping cracks, you must not use CFS. In that case we would recommend a full relining.
3. What about the need to downsize for many gas and oil applications?
This is an occasion that would require a liner rather than CFS. Conversely, the advantage of CFS is that it does not downsize the flue substantially.
4. Is Ceramic Flue Sealant a liner?
No, CFS is not a zero clearance liner, although it does have many of the positive properties of a cast-in-place liner. Unlike a retrofit liner, it has minimal insulative qualities and disperses heat in a unique way that is not recognized by UL 1777. This is why it is tested to applicable sections. We describe it as a “Sealant,” which will accomplish desirable repairs in a situation where a whole new liner may not be necessary.
5. What about code requirements that all “masonry chimneys should be lined”?
Full liners are always desirable however many chimneys built before the advent of clay-tile liners (and the development of codes requiring liners) continue to exist in varying stages of deterioration with no prospect of ever being lined. These chimneys, on a case-by-case basis, would all benefit greatly from the application of Thermocrete™ Ceramic Flue Sealant. CFS is a far better alternative, in many cases, than an across-the-board industry pronouncement that “without a liner chimneys plainly should not be used!” We know they are being used, and will continue to be used. It is far better to seal them than ignore them. The application of CFS does not preclude lining at a future date.
6. Has Thermocrete passed any official tests or certifications? What about U.L.?
Yes. CFS was listed by Warnock Hersey in 1999 and has been rigorously tested. See Technical Data Sheet.
7. How will CFS stand up to brushing during chimney cleaning, especially with flat wire brushes?
No special care is needed during cleaning. Although CFS is 5 times harder than cast-in-place liners and it has a remarkable capability for bonding firmly to chimney walls, we do not recommend the use of rotary chains.
8. How does installation of CFS work in cold weather?
The problems you may encounter in cold weather are primarily related to the application process not the finished product. Whenever you are dealing with water in below freezing conditions, there are precautionary measures that need to be taken, but if done properly, the CFS can be sprayed in weather as cold as 20º F.
The great thing about CFS is that a few minutes after the end of spraying, many heating appliances can be fired to complete the cure! No worries about plummeting nighttime temperatures!
9. What about creosote wicking through tile liner cracks and remaining a hazard on the backside of existing tile?
Actually, the quantity of creosote that works its way through small tile cracks is inconsequential. We have never seen a dangerous quantity of creosote on the backside of minimally cracked tile, and to pretend otherwise is self-serving. With a liberal coating of CFS in place, hot gases cannot penetrate the repaired tile to reach any creosote film. CFS will provide a heat-diffusing barrier to minimize temperature rise on the back side.
10. How about eroded and spalled tile liners serving oil and gas appliances?
CFS is excellent in this situation. Since CFS is only as good as the substrate it is applied to, you should brush and peel away all loose liner materials first. The liner should generally remain, at minimum; 3/8” thick at most spots. With CFS repair, then the tile liner will be restored to its original thickness. Any holes should be backed closely by masonry walls or plugged with refractory materials. The CFS coating will then strengthen and bind together the old surface with a new acid and moisture-resistant seal.
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