Harvia WHP1000 Sauna Wood Stove Chimney Extension, 39.4 in, Stainless or Black Steel

The Harvia WHP1000 chimney extension adds 39.4 in (39.3″) of height to a Harvia WHP steel chimney. Its grooved slot-and-lock joint winds the smoke pipe and insulated outer casing together, so the assembled chimney resists movement caused by rapid temperature changes. Choose stainless steel (WHP1000) or black powder-coated steel (WHP1000M) to match your chimney kit, and install it indoors or outdoors.

Features

• Adds 39.4 in (39.3″) of insulated chimney height
• Grooved joint mechanism locks smoke pipes in place and prevents movement from temperature changes
• 8.7 in (8.6″) insulated outer casing with 4.6 in smoke path, matches all Harvia WHP chimneys
• Available in stainless steel or black powder-coated steel
• Suitable for indoor and outdoor installation
• Designed, engineered, and made in Finland
• Limited 2-year warranty (consumer use); limited 1-year warranty (commercial use)

What’s Included

• 39.4 in insulated chimney extension module
• Installation manual

Specifications

Compatibility

Fits the Harvia WHP1500 / WHP1500M chimney kit and all Harvia WHP steel chimney modules. Need less height? The Harvia WHP500 19.7 in extension adds half as much. A damper, roof accessory kits, and 4.6 in smoke pipes are also available in the Harvia chimney family at Sauna Marketplace.

Planning note: Harvia’s WHP steel chimney system installs vertically only and is designed for wood-burning sauna stoves in standalone outdoor sauna buildings. Keep at least 4″ (4 in) of clearance between the insulated outer casing and any combustible material, and confirm your installation with your local building authority before you build.

Good to Know

How tall can a Harvia steel chimney be?

Harvia limits the total chimney height to 16.4 ft, with no more than 6.5 ft of chimney above the last lateral support. One WHP1000 extension plus a WHP1500 kit stays comfortably inside those limits for most single-story sauna buildings.

What is the difference between WHP1000 and WHP1000M?

They are the same 39.4 in insulated extension; WHP1000 is stainless steel and WHP1000M is black powder-coated steel. Match the finish of your existing Harvia chimney kit.

Can I install this extension at an angle?

No. Harvia steel chimneys are approved for straight, vertical installation only. Offsets and elbows are not part of the Harvia WHP 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)
• 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 (this page)

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)