Harvia Onni Infrared Sauna: One or Two Person
The one cabin here that draws less than a kettle and needs no electrician.
From £3,978.00
Free standard delivery on orders placed by 30 September 2026
Delivery from £250 on orders placed after that
Exact cost confirmed for your postcode before dispatch.
Typically 8 to 10 weeks, depending on availability and the season. Email us for a current date, or we confirm yours when you order.
- About 7.8A at 230V, so an ordinary socket rather than a dedicated circuit
- Full spectrum radiators and carbon heating plates, dimmable
- 46mm abachi cabin with an 8mm toughened glass door
- Cabin
- Abachi element cabin, 46mm walls, black aluminium front frame
- Size
- 1000mm wide for one, or 1300mm for two, both 1043mm deep and 2000mm tall
- Heat
- Full spectrum infrared radiators plus carbon heating plates, dimmable
- Power
- 1400W in the Mini or 1800W in the Small, on one circuit
- Supply
- About 7.8A at 230V, so a normal socket rather than a dedicated circuit
- Inside
- Colour light, temperature display, a heating period limiter and an MP3 player
- Glass
- 8mm toughened door, 1808 by 600mm, hinged on the right
Infrared is not a smaller sauna, it is a different thing: no steam, no stones, no warm up, and a session that costs pennies. This is where the range starts, and for a lot of houses it is the only one that will actually fit.
Delivery & installation
Delivery is available across the UK and the charge is confirmed for your postcode in writing before anything is dispatched. Offshore and some remote postcodes cost more, and we tell you the figure before you commit rather than after.
The cabin arrives flat, as elements. It is the smallest thing in this range and the easiest to get into a house, but the package count and weights are being confirmed with the distributor and are not published here until they are.
Installation can be arranged where you would rather not build it yourself, although this is the one cabin in the range most people will put together themselves.
Warranty
Two years on the cabin against manufacturing defects, and two years on the radiators and the control, under Harvia's published warranty terms.
One thing we will not claim. Harvia give an extra year on registered electrical sauna heaters. Their terms do not say whether an infrared radiator counts as one, so we do not state that the extra year applies here. Register it anyway when it is installed; it costs nothing and the question is Harvia's to answer, not ours to assume.
Harvia name the exclusions plainly, and they are the parts that wear: heating elements, timers, relays and light bulbs. Anything caused by not following the installation, use or maintenance instructions is excluded too. This cabin plugs into an ordinary socket, so the commonest cause of trouble on a traditional sauna, the electrical supply, does not arise here.
The warranty runs from the date of purchase. Harvia's own terms allow a claim to be made to the seller, so claims come to us. One email, and we deal with the distributor and Harvia on your behalf rather than handing you a phone number.
Returns
Until the order is placed with the supplier you can cancel and be refunded in full, with no reason needed.
After that the cabin is on its way from the factory, and our returns policy sets out exactly where that leaves you. Check the packages against the parts list on the day they arrive; anything that arrives damaged or faulty is ours to put right either way.
Who this is actually for.
Every product here is described with the honest opposite beside it: who it suits, and who should be looking at something else.
1800 watts is about 7.8 amps at 230 volts, so this runs from an ordinary socket. Every other sauna on this site needs a dedicated circuit and an electrician's certificate. This one needs a plug and a wall.
Worth confirmingyou want a Finnish sauna. This does not make steam, there are no stones and you cannot throw water. It warms you, not the room, and people who wanted the other thing are always disappointed.
There is no warm up to wait for and a session costs a few pence, so it gets used on a Tuesday evening rather than saved for the weekend. That is the honest case for infrared: not that it is better, but that it is used more.
Worth confirminga sauna is an occasion for you. If the ritual is the point, the heat of a traditional room is the point with it, and a 3.6kW cabin is the smallest one that delivers it.
The product that gets used is the one worth recommending, and it is not always the largest one.
The measurements that decide it.
Read this before anything else. This is the smallest cabin in the range and the one most likely to fit, but it still has to get through the door and stand up in the room.
Both sizes are 2 metres tall and 1.043 metres deep. The difference between them is width alone, 1 metre against 1.3.
From order to first use.
Here is each stage, and who does what. Before you order, email hello@tarnfell.com and we will confirm the current lead time and the delivery cost for your postcode in writing.
- Week 0
Size and room check
One seat or two, and where it stands. The door is hinged on the right and cannot be swapped, so which way the room opens matters more here than on the bigger cabins.
- Before it arrives
A socket, and that is all
No dedicated circuit and no certificate. Check the socket is on a circuit that is not already carrying something heavy, and that it is not on the far side of the room from where the cabin will stand.
- Delivery day
To the door, in elements
Check the packages against the parts list on the day they arrive and tell us about anything damaged or missing straight away.
- Build day
Two people, a couple of hours
Element cabins go together with clips and screws rather than trades. This is the one product in the range most people will build themselves without regretting it.
- First use
Plug it in
Set the temperature, set the time limiter, and give it about fifteen minutes. There are no stones to stack and no water to add.
What owning one actually involves.
The handful of things that decide whether this is still in use in year three.
Harvia's data sheet lists an EU power cord, which is normal for a cabin built for the European market. A UK cabin needs a UK plug, and we settle that with you in writing before anything is dispatched rather than leaving you to find out on the doorstep.
Full spectrum radiators at the front, carbon plates around the sides. There is no warm up to speak of and the air never gets hot the way a Finnish room does. Some people love that and some people miss the steam.
No stones, no water, no filter, no chemistry. Wipe the benches down, keep the glass clean, and that is the whole list.
A bathroom, a spare room, a home gym or a garage that stays dry. It needs no plumbing, no drainage and no ventilation work.
The running costs, with the working shown.
The purchase price is public; the running cost rarely is. Ours are published with the assumptions stated, so you can check the arithmetic and change it for your own tariff.
about 24p
1800W for half an hour is 0.9 kWh at 26.11p. There is no warm up, so this is the whole cost of the session.
about £49
208 sessions at 24p. For comparison, the same frequency in an 8kW traditional cabin comes to roughly £600.
none on a schedule
No stones, no filter, no pump and no chemistry. The radiators and heating plates are the only consumable parts and they are not on a service interval.
Assumptions: electricity at the Ofgem price cap unit rate of 26.11p per kWh, 1 July to 30 September 2026, including VAT. Figures are calculated from the rated total output, 1400W for the Mini and 1800W for the Small, and assume the radiators run continuously, which overstates the real figure once they start cycling.
What you have to do, and what the rules require.
Everything you have to do, and how often.
| Job | How often | Who |
|---|---|---|
| Check the plug and the socket Total load is 1400W or 1800W, about 6.1A or 7.8A at 230V, so an ordinary 13A socket carries it. Harvia list an EU power cord, so confirm the UK plug arrangement before first use. | Once, before first use | You, or an electrician for the plug |
| Wipe the benches and the glass A damp cloth and warm water. Nothing film forming on the timber. | Monthly, or after heavy use | You |
| Leave the door open after use There is no steam, but there is perspiration. Airing it keeps the abachi clean and dry. | Every session | You |
| Set the heating period limiter The cabin has an adjustable limiter built in. Use it rather than relying on remembering. | Once, then as you like | You |
Where this comes from.
Regulation and guidance, linked so you can read it yourself. None of it is our opinion.
- Onni Mini is 1400W total, one seat; Onni Small is 1800W total, two seats, individually dimmableHarvia data sheets, articles 1-053-078 and 1-053-079
- Both cabins are 46mm abachi element cabins with an 8mm toughened glass door, supplied with an EU power cordHarvia data sheets, Onni Mini and Onni Small
- Electricity unit rate of 26.11p per kWh, 1 July to 30 September 2026Ofgem energy price cap
- Plugs and sockets in UK domestic installations are rated 13ABS 1363
Every figure the makers publish.
- Warranty
- 2 year cabin and radiator warranty
Figures are from Harvia's own data sheets for the Onni Mini, article 1-053-078, and the Onni Small, article 1-053-079. Where a figure is ours rather than theirs, it says so.
What arrives, and what does not.
- The cabin as abachi elements with the black aluminium front frame
- The 8mm toughened glass door and glass element, with a wood and wood handle
- Every radiator and heating plate: 1400W in the Mini, 1800W in the Small
- The control with its temperature display, dimming, colour light, MP3 player and heating period limiter
- The power cord, supplied as an EU cord
- Assembly, unless you ask us to arrange it
- Delivery. It is quoted for your postcode and confirmed in writing before dispatch
Reasons to buy something else.
This is not that and it never will be. If throwing water is the point, buy a traditional cabin and be happier for it.
One seat or two. There is no larger Onni in the range we can order, and squeezing a third onto a bench 1.3 metres wide is not a plan.
Harvia hinge this door on the right and do not offer it the other way. On a cabin this size in a small room, that is a real constraint, not a detail.
There is a timer on the cabin and nothing beyond it. Harvia list this model as not bus compatible and not compatible with their own app.
If any of these apply, say so and we will point you at what does suit you, including when that is a cheaper product or one we do not sell.
What we know, and how we know it.
Not a rating. A record of where every figure on this page comes from: what we have checked against a published document, what a maker states and we have not yet checked, and what is still open.
- Dimensions, construction and output
-
Verified
Sizes, wall thickness, timber, seat count, glass sizes and every wattage are taken from Harvia's own data sheets for articles 1-053-078 and 1-053-079.
- Current drawn
-
Information not yet published
6.1A and 7.8A are our own arithmetic from Harvia's rated total output at 230V. Harvia do not publish a current figure for these cabins.
- The UK plug
-
Information not yet published
Harvia list an EU power cord. Whether the distributor supplies these with a UK plug fitted is being confirmed in writing before this page becomes buyable.
- Weight, packages, warranty and lead time
-
Information not yet published
None of these appear on Harvia's data sheets. All four are being confirmed with the distributor.
- The Sienna and Onyx models
-
Information not yet published
Harvia's media library carries a newer Onni Sienna and Onni Onyx. The distributor has told us they are not yet launched and are new for next year, so they are not offered here and no figure from them appears on this page.
These states move as the evidence does. When a figure is measured on an installed cabin, by us or by an owner who will let us, it moves from stated to verified and this section says so.
Weighing this against another sauna? Let us do the homework.
Choosing between two saunas takes evenings of research, so let us carry it. Name the other one you are considering and we will send a straight comparison, including where the other one wins.