During combustion, all boilers produce gasses that need to be emitted outside of your home. The pipework for this is known as a flue.
It's time for an update
You've been using your good friend IE for quite some time now. It has been a reliable companion for probably the last 20 years.
Unfortunately, due to technology constantly evolving, we would like to kindly ask you to update your browser to one of your liking from the ones listed below. This will ensure that you're going to have good time on our site. Actually, any site really.
Farewell, Internet Explorer.