It is some time since I installed your wonderful Windkat Chimney Cowl (April this year) but we have only recently had to start heating the home (the log burner is our only source of heating). Please find attached two pictures, one showing the fire burning with flue temperature gauge and heat powered fans and the second one taken within a minute showing how clean the burn is!
We used to have trouble with slow burning and large amounts of smoke along with our downdraft. We now have very clean burning with no problems getting things started or keeping them going. As you can see (or not) there is almost no smoke visible demonstrating how efficient how log burner has become. We are using between 2/3 and 1/2 the amount of wood we were using before your cowl was fitted and only need to empty the ash pan every four or five days instead of daily (another demonstration of how the efficiency has been improved!).
I have to say I was nervous spending the amount I did on a cowl but have absolutely NO regrets whatsoever.