PLEASE VIEW THE INFOGRAPHIC BELOW
If at all unsure then purchase the fitting pack with 2x 45 degree elbows. The elbows can be used to create an offset to move the stove away from the back wall if required. You might not need the elbows. No problem… at end of job just send them back and we will refund (not scratched and in original box please).
Liner does not bend over short distances. If your chimney enters the opening "off the vertical" then also purchase 1x 30 degree vitreous elbow (it is always 30 degree trust me). You can always send it back! See image underneath the infographic.
If your liner enters your cavity at an angle a single extra 30-degree elbow may be required. See image below:
It might be the case that you have 3x elbows: two to make an offset to move the stove away from the back wall and a third to point in the direction of the incoming liner.