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Underwriters Laboratories (UL) is a not-for-profit organization, which develops, revises, and implement standards for safety. The UL 1777 Standard tests chimney liners as a system within a masonry chimney. UL 1777 was designed to test the liner to the appropriate temperatures as well as putting the liner through strength tests.

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There are many parts to the UL 1777 tests. The Temperature Tests determine whether the exterior of the chimney will stay cool enough so that combustibles touching the chimney (i.e.: floor joists, attic rafters, etc.,) won't ignite. The temperature test for solid fuels (coal and wood) simulates a chimney fire.

Similar tests, but with lower temperatures are done for oil, wood pellet and gas applications. There is also a special test, UL 1738 for condensing gas appliance flues. During this test the liner is put through an accelerated corrosion test in addition to the other tests.

Other tests that the liners must go through include the Vertical Support Test, Loading Test, Strength Test, Sweep Test, Abrasion Test, Torsion Test, Flexibility Test and Rain Test. After passing all of these tests, the manufacturer must then work with UL for approval on their written installation instructions.

Then, they must enlist in UL's Follow Up Procedure. This allows a UL representative to visit the factory unannounced, usually once every three months, to verify that the materials are in compliance with their listing.

To have a truly UL Listed product, it must be subjected to Underwriters Laboratories for testing and later for their suprise visits to the manufacturing facility, and of course, the product must bear the UL trademark . Some companies test to UL Standards by another testing laboratory. Their product can't be UL Listed because UL didn't do the test. They often advertise as "Listed to UL 1777".

Here at HomeSaver, we have maintained UL Listings for almost two decades. We are proud to promote the UL Listings that we have. Here are the following UL listed HomeSaver chimney liners:

HomeSaver GasFlex
HomeSaver Pro
HomeSaver RoundFlex
HomeSaver RectangleFlex
HomeSaver OvalFlex

Thank you for your interest in HomeSaver Chimney Liners and our UL listings.