150/250

150/250 insulated chimneys are designed specifically for higher-powered heating appliances that require strong draft and high throughput for efficient operation. This designation refers to the chimney’s two main dimensions:

150 mm: The chimney’s internal diameter. This is an ideal solution for higher-powered heating appliances, such as larger central heating boilers, industrial heating systems, or fireplaces that heat multiple rooms.
250 mm: The chimney’s external diameter. This provides sufficient space for a high-quality insulation layer, which helps keep the chimney’s outer surface safely cool and improves draft.