Opus Octave 70 B box stove standing on a hearth in a stone fireplace

Opus Octave 70 B 5kW Wood Burning Box Stove

£2,125.00
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Opus Octave 70 B box stove standing on a hearth in a stone fireplace
  • Opus Octave 70 B box stove standing on a hearth in a stone fireplace
  • Opus Octave 70 B stove on a low bench with the fire lit
Opus Octave 70 B 5kW Wood Burning Box Stove

Opus

Opus Octave 70 B 5kW Wood Burning Box Stove

Customers rate us 4.9 out of 5 (103 reviews)
£2,125.00
Free delivery to England and Wales on orders over £50.

Is it right for you?

  • Room size: one room of up to about 29 m² with a 2.4m ceiling (rule of thumb). Check your room
  • Chimney: works with a lined chimney, or a twin-wall flue if you don't have one.
  • Fuel: dry logs only.
  • Smoke control: exempt, so you can burn logs in a smoke control area.
  • Fitting: must be fitted by a HETAS registered installer. Find one by postcode
What else will I need?
Free delivery to England and WalesUsually 3 to 10 working days. The courier usually contacts you to book a day. Scotland and Northern Ireland charges are shown at checkout.
  • 30 days to change your mind
  • Manufacturer's UK warranty
  • UK suppliers
  • 5kWHeat output
  • Wood BurningFuel
  • Ecodesign2022 compliant
  • Smoke controlExempt appliance
  • 80.7%Efficiency
  • 3 yearsWarranty

The Opus Octave 70 B is the Octave 70 as a standalone firebox with no legs, to stand on a bench, a raised hearth or a concrete shelf. It is rated at 5kW, runs from 3.3kW up to 12kW at 80.7% efficiency, and is smoke control exempt in England when burning approved fuel.

Why choose the Octave 70 B

  • Low 555mm profile that sits directly on a hearth, bench or shelf.
  • Wide window with primary, secondary and tertiary air.
  • Convection body spreads warm air around the room.
  • Takes logs up to 600mm long; 150mm top flue.
  • Ecodesign ready, energy class A+, smoke control exempt in England.
Full details and specifications

What you'll need

Everything to get this stove lit

A stove on its own isn't enough. Here's what comes in the box, what else you'll need, and what your installer brings.

In the box

  • Heat-resistant glove; baffle plate

You'll also need

  • A carbon monoxide alarm. Required by law in the room with the stove.
  • Stove pipe to connect it to the flue. Your installer will tell you the length.
  • A hearth for it to stand on, if you don't already have one.
  • A chimney liner or twin-wall flue. Your installer supplies this.

Your installer brings

A stainless steel liner sized to the stove and a register plate to seal the chimney, usually after the chimney has been swept and checked.

Fitting, testing and a certificate showing it meets Building Regulations. Keep it for your home insurer and for when you sell.

Ask for one quote that covers the survey, flue, fitting and certificate. Using someone who isn't HETAS registered? Your local building control must approve the work before you use the stove.

Find a HETAS installer by postcode Got your installer's parts list? Email it and we'll price what we sell How flues and installation work

How buying a stove works

  1. Check it fitsUse our size calculator, or email us a photo of your fireplace and the room size and we'll suggest stoves that suit.
  2. Book a HETAS installerThey survey the chimney, quote for the flue and fitting, and tell you which parts to order.
  3. We deliverFree to England and Wales, usually within 3 to 10 working days. It weighs 110kg, so have help and a sack truck ready. Book the fitting date once it has arrived.
  4. Your installer fits itThey fit the stove and CO alarm, test it and register it. You get a certificate to keep.

The numbers, in plain English

5kW heat output
Enough for a room of about 29 m² with a 2.4m ceiling (rule of thumb)
80.7% efficient
How much of the fuel's heat it turns into useful heat
150mm flue
The flue size your installer needs
Smoke control exempt
Legal to burn logs in a smoke control area
60cm logs
The longest log it takes
H 555 x W 695 x D 438 mm
Size (height x width x depth)
110kg
Heavy: it needs at least two people and a sack truck to move

Full specifications, clearances and the manual are further down the page.

About this product

Will it suit your space?

As a rough guide, an average room needs about 1kW for every 14 cubic metres, so its 5kW suits around 70 cubic metres. Older, draughty or high-ceilinged rooms need more, and a heat-loss check by your installer gives the right answer.

Firepower lists the 70 B at 555mm high, 695mm wide and 438mm deep. Allow 400mm to combustible materials at the sides and rear and 1500mm in front.

Specifications

Model Opus Octave 70 B (firebox, no legs)
Heat output 5kW nominal; runs from 3.3kW up to 12kW
Efficiency 80.7%, energy class A+
Fuel Wood logs only, up to 600mm long
Dimensions H 555 x W 695 x D 438mm
Weight 110kg
Flue 150mm, top outlet (centre 128mm from the back)
Outside air 120mm, with the optional direct air adaptor
Construction Welded steel convection body, firebrick lining, cast iron grate
Clearance to combustibles 400mm rear and sides, 1500mm in front
Ecodesign Ecodesign ready
Smoke control Exempt in England on wood logs up to 20% moisture
Warranty 3 years (glass, seals, grate and firebricks excluded)

What's in the box

A heat-resistant glove; the baffle plate is packed inside the firebox.

Installation and safety

Have it fitted by a HETAS-registered installer or signed off by Building Control, with a carbon monoxide alarm in the same room. The Octave is not suitable for a shared chimney.

Questions

Can I use it in a smoke control area?

Yes. DEFRA lists the Opus Octave 70B as exempt in England when burning wood logs with up to 20% moisture, with the permanent air stop the exemption requires.

How often does it need refuelling?

Opus says that to burn at its nominal 5kW it needs about 2.5kg of logs every 45 to 50 minutes.

What can I stand it on?

Opus suggests an Opus bench, a custom hearth or a concrete shelf. Whatever it stands on must be non-combustible, level and able to take 110kg; your installer will confirm it meets Approved Document J.

See the full Opus range, DEFRA approved stoves and Ecodesign stoves.

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Why buy from Glowing Flames?

  • Free delivery

    Free to England and Wales on orders over £50 (£9.99 below that). Large items come on a pallet and the courier books a day with you.

  • Real advice

    Not sure it will fit or work with your chimney? Send us a photo and we will check.

  • UK warranties

    Supplied by the manufacturer or its UK distributor, with the manufacturer’s UK warranty and spares.

  • 30 days to change your mind

    Change your mind up to 30 days after delivery, with no restocking fees and fixed collection prices for large items.