Our Windkat cowl was installed about a week ago, and I'm very pleased to say that it has completely cured the problems that we were having with the chimney. Previously the fire ran and drew well once burning, but was very difficult to start and would often fill the room with smoke, due to a column of cold air falling down the chimney whenever the fire was not burning and that also created a creosote smell in our lounge most days, which was particularly obnoxious on cold and wet days. We had previously taken advice from several 'HETAS technicians' to use extra newspaper to heat the chimney before lighting the fire, which just created thick smoke in the room; one told us to have the chimney relined at a cost of £2500, but couldn't explain why that would help; and finally one told us to demolish and rebuild the chimney, which we refused to consider, as again the HETAS engineer couldn't calculate, justify or indemnify that the idea would have any effect.
Conversely, your advice was well considered, you answered all of my questions quickly and informatively and it was clear that your priority was a happy customer. Your customer service and your product have been exceptional; the installation was a simple 10min task, and the flue now draws constantly. The creosote smell has gone, the fire is a dream to light, and when the fire is not lit the room is warmer than it was before as there is no cold draught.
As an added advantage, I note a recent study claimed that using wood burners triple the airborne pollution inside the home; since installing the Windkat cowl, I have measured the particulate pollution, and there was no measurable difference in PM2.5; before lighting, when using, lighting or refuelling our stove. Given the smoke issues we had previously, I believe that your product can also improve indoor air quality.
Photos below - Windkat installed in the chimney and smoke being drawn into the cold firebox from a distance: