Square to Round Chimney Adapter
RENOFAST Stainless Steel Rectangular to Round Flue Adapter
Product Description
The RENOFAST "Rectangular-to-Round" adapter is a specialised shaped component designed to connect the outlet spigots of heating boilers or fireplace inserts, which have a rectangular or square cross-section, to the main round chimney system.
The product represents a complex geometric structure (a truncated pyramid transitioning into a cone), which ensures a smooth aerodynamic transformation of the flue gas flow from one cross-sectional shape to another without creating excessive resistance or turbulence.
Custom Manufacturing and Features
Since the dimensions of outlet spigots vary significantly between boiler manufacturers, these adapters are manufactured primarily to order based on the client's individual dimensions. The production time is 3–10 working days.
- Any Configuration: We can manufacture both symmetrical adapters (centres of the rectangle and circle coincide) and complex offset (eccentric) adapters if required by the boiler room geometry.
- Connection Types:
- Rectangular side: Overlap fit onto the boiler spigot or flanged connection (according to customer drawings).
- Round side: "Male" socket connection (narrowed, fits inside pipe) or "Female" (expanded, fits over pipe).
- Material: Only acid-resistant stainless steel AISI 304L / 316L is used (thickness from 0.6 mm), capable of withstanding high temperatures and aggressive condensate.
Drawings and Configurations
Technical Specifications
| Element Type | Custom Adapter (Rectangular-to-Round) |
| Material | Stainless Steel AISI 304L / AISI 316L |
| Steel Thickness | from 0.6 mm (upon agreement) |
| Certification | CE (material and welding technology) |
Required Ordering Data
To manufacture the item, please provide a sketch indicating the following parameters:
- A x B (mm): Internal or external dimensions of the rectangular/square spigot (specify fit type).
- D (mm): Diameter of the round part and connection type ("Female/+" or "Male/-").
- L (mm): Total installation length of the adapter.
- T (mm): Length of the straight rectangular section (if needed).
- FL (mm): Flange dimensions and parameters (if a flanged connection is required).
- Offset: Specify if the centres of the openings do not align (eccentric adapter).






