Harvia WZ115120 Reducing Pipe, 4.6 in, Stainless Steel

The Harvia WZ115120 reducing pipe connects a smaller-diameter pipe to a larger one within a sauna chimney system. The stainless steel reducer gives a precise, secure joint between mismatched sections, keeping the smoke path sealed for reliable draft and safe smoke removal.

Features

• Securely joins a smaller pipe to a larger pipe
• Precise fit for a straightforward installation
• Maintains proper draft and smoke removal
• High-temperature resistant stainless steel
• Limited 2-year warranty (consumer use); limited 1-year warranty (commercial use)

What’s Included

• Reducing pipe

Specifications

Compatibility

For Harvia’s 4.6 in smoke-pipe system and the WHP steel chimney. Transitioning from Harvia’s 4.6 in outlet to a 6″ US Class A chimney instead? Use the Harvia WZ115155 Euro-to-USA adapter, also at Sauna Marketplace.

Good to Know

When do I need a reducing pipe?

When joining Harvia smoke-path components of slightly different diameters, for example, mating a stove collar or damper section to the next pipe size in the run. It keeps the joint concentric and sealed.

Is this the same as the WZ115155 adapter?

No. The WZ115155 converts Harvia’s 4.6 in (4.5″) outlet to 6″ US pipe for hybrid installs; the WZ115120 is a reducer within the metric Harvia system.

Designing a Harvia Chimney System

Every part on this page belongs to Harvia’s modular WHP steel chimney system: a 4.6 in (4.5″) smoke path inside a 8.7 in (8.6″) insulated casing, assembled with slot-and-lock joints. Here is how a complete system comes together:

1. Start with the chimney. For pitched roofs, the WHP1500 kit (59.1 in chimney plus rain cap, tilted rain flange, smoke pipe, and ceiling lead-through set) is the core of the system. For flat roofs and barrel saunas, the WHP1000500 package bundles the chimney with the symmetric roof kit.
2. Connect the stove. Bridge the stove collar to the insulated chimney with 4.6 in WZ smoke pipes (7.9 in, 19.7 in, or 3.3 ft). Add the WZ115030SP damper plate at the stove to control draft while firing, a WZ115120 reducer where pipe sections step down, or the WZ115155 adapter if you are transitioning to 6″ US Class A pipe.
3. Reach your height. Add WHP500 (19.7 in) or WHP1000 (39.4 in) extensions. Stay within Harvia’s limits: 16.4 ft total chimney height, no more than 6.5 ft above the last support, lateral supports every 9.8 ft.
4. Go through the roof. Choose the roof kit that matches your roofline: WHP-AS for tilted/pitched roofs, WHP-ASSYM for flat roofs and barrels. Replacement rain collars: WHM22 (tilted) and WHM24 (symmetric). Add a snow barrier above the chimney where sliding snow can load the flashing.
5. Seal and control. The WHM25 vapor barrier restores the vapor-tight layer where the chimney passes the sauna ceiling; the WHP270 insulated damper closes the flue after the fire is fully out so the sauna holds its heat.
6. Finish the stove side. Stone-filled covers (WL300 for Legend stoves, WL300PC for Cilindro) absorb radiant heat from the smoke pipe and significantly reduce its required safety distances.

Key clearances and rules: vertical installation only; 4 in (4″) from the insulated casing to combustibles; 19.7 in (stainless) or 14.8 in (black) from non-insulated smoke pipe unless shielded; designed for wood-burning stoves in standalone outdoor sauna buildings. Confirm your plan with your local building authority, and if you would like help speccing the system, talk to us; we design these daily.

Shop the Complete Harvia Chimney System

1. Start with the chimney

• WHP1500 Chimney Kit, 59.1 in (stainless or black), the system core
• WHP1000500 Complete Chimney Package for flat roofs & barrel saunas

2. Connect the stove

• WZ Smoke Pipes, 4.6 in (7.9 in / 19.7 in / 3.3 ft, stainless or black)
• WZ115030SP Stove-Side Damper Plate (draft control while firing)
• WZ115120 Reducing Pipe (joins mismatched pipe sections) (this page)
• WZ115155 Adapter, 4.5″ Euro to 6″ USA (hybrid Class A transitions)

3. Reach your height

• WHP500 Chimney Extension, 19.7 in
• WHP1000 Chimney Extension, 39.4 in

4. Go through the roof

• WHP-AS Roof Accessory Kit for tilted / pitched roofs
• WHP-ASSYM Roof Accessory Kit for flat roofs & barrel saunas
• WHM22 Replacement Rain Collar, tilted roofs
• WHM24 Replacement Rain Collar, flat roofs & barrels

5. Seal and control

• WHM25 Chimney Vapor Barrier (seals the ceiling penetration)
• WHP270 Insulated Smoke Damper (retains heat after firing)

6. Finish the stove side

• WL300 Smoke Pipe Cover for Legend stoves (cuts clearances)
• WL300PC Chimney Cover for Cilindro stoves (cuts clearances)