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HUUM UKU Extension Box, a white wall-mounted enclosure with the HUUM logo and cable entries along the top
HUUM

HUUM UKU Extension Box for Heaters over 11 kW

$773
$899
Save $126
+ Free Shipping Free Delivery within the Continental US
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  • Authorized retailer · manufacturer warranty
In stock — estimated delivery in 7–12 days
Usually ships by UPS or FedEx; a signature is generally not required.
Description

What is the HUUM UKU Extension Box?

The HUUM UKU Extension Box lets a HUUM UKU control run an electric sauna heater over 11 kW. The UKU runs heaters up to 11 kW on its own; with the extension box it runs heaters up to 18 kW. HUUM's wiring sheet says it is used only with the UKU Wi-Fi and UKU Local control systems.

Which HUUM heaters need the extension box?

Among the HUUM heaters Topture sells, the HIVE 12, 15 and 18 kW are over 11 kW, and the HIVE 12, 15 and 18 kW packages include the extension box. The DROP, CLIFF, STEEL and HIVE Mini are all 11 kW or less and run on a UKU alone.

How is the HUUM UKU Extension Box installed?

HUUM's wiring sheet: the extension box goes outside the sauna room, near the UKU main module, fixed to the wall with 4 screws. The main module and the extension box must each be connected to their own circuit breaker, and HUUM's wiring diagram replaces the one in the UKU manual for heaters over 11 kW. The wiring must be done by a licensed electrician.

Specifications

HUUM UKU Extension Box specifications

HUUM UKU Extension Box (HUUM wiring sheet H3283 v5)
Used with HUUM UKU Wi-Fi and UKU Local
Heater power Heaters over 11 kW, up to 18 kW with a UKU
Rating 240 V 2~, 2 × 63 A, 60 Hz
Enclosure IPX4
Location Outside the sauna room, near the UKU main module
Circuit Its own circuit breaker, separate from the UKU main module
Made in Estonia
HUUM part number H2003012

What's in the box?

  • HUUM UKU Extension Box
  • Wiring instructions
Documents

HUUM UKU Extension Box Wiring Instructions (US)

HUUM UKU 4.2 User Manual (US)

Warranty

HUUM warranty periods

HUUM's limited warranty (Limited Warranty Terms and Conditions, US, v2) covers new HUUM products bought from HUUM or its authorized dealers, such as Topture, against defects in materials and workmanship. The period starts on the date the end user buys the product.

HUUM products and warranty periods (HUUM warranty terms, US, v2)
HUUM product Private use Commercial use
Electric sauna heaters 3 years 1 year
Wood-burning sauna stoves 3 years 1 year
Control units (UKU) 3 years 1 year
Spare parts 1 year 1 year

HUUM counts as commercial use a business using the product commercially, a private owner using it commercially, or a private owner using it for more than 1,500 hours in 12 months.

What the warranty does not cover

  • Heating elements of electric heaters
  • HUUM accessories, such as rails, reflectors, flanges, protective bedding and chimney parts
  • Door glass and ash grate of wood-burning stoves
  • Sauna stones
  • All controller sensors
  • Damage from a heater that is the wrong size for the room, from unsuitable stones, or from installation, use or maintenance that does not follow HUUM's manuals

What keeps the warranty in effect

  • Inspect the product when it arrives and report any visible damage within 7 days, with photos, before installing it.
  • Install it following HUUM's manual and local building, electrical and fire codes. An electric product must be connected by a licensed electrician, with proof of the installation.
  • Report a defect within 30 days of finding it. For products bought from Topture, report it to Topture, which passes the claim to HUUM and helps with troubleshooting.

Read HUUM's full Limited Warranty Terms and Conditions (US)

REAL HOMES. REAL REVIEWS.

What Topture Customers Say

Topture is rated 4.9/5 across 462 customer reviews

We thought about buying a sauna for years and finally did. We absolutely love it, especially in the winter. It’s incredibly easy to assemble with two people the whole family uses it.

Verified buyer

Ordered this sauna fall 2024 and we love it. No better feeling during a Minnesota winter. Lastly, I have to mention the customer service for this purchase has been like no other. Any questions or requests I had were addressed immediately by Topture. I got more than I expected from them and have already recommended them to several people looking for saunas. SO if you're thinking about it, JUST DO IT already..

Verified buyer

Thanks for the great service - greatly appreciated.

Verified buyer
462 Customer Reviews

Product and store reviews from Topture customers, collected by Judge.me.

Lifetime Expert Support

Same team before and after the sale, from sizing to warranty support.

Authorized HUUM Retailer

Sold by Topture, with the applicable manufacturer warranty.

Full-Value Freight Protection

Freight damage? We help coordinate the claim and replacement process.

STILL UNSURE?

Frequently Asked Questions

General Topture Questions

Where are you located, and where do you ship from?

Topture is an online retailer serving customers in the contiguous United States. The company is Topture LLC, a Wyoming limited liability company, and its registered business address is 30 N Gould St, Ste N, Sheridan, WY 82801.

Orders ship from manufacturer and distributor warehouses in the U.S. and Canada, and some products ship directly from the manufacturer in Europe. Each product page shows its estimated delivery time.

How much is shipping?

Orders over $200 ship free within the continental United States. Orders under $200 carry a small shipping fee.

Two exceptions: SaunaLife and ThermaSol products carry a freight charge at any order value, and sauna stones ordered without a heater ship at $60 per box because of their weight.

Every charge is shown at checkout before you pay.

Do you provide financing?

Absolutely! To view your financing offer, simply select Shop Pay Installments as your payment method at Step 3 of checkout.

You'll need to enter a debit card to receive your offer, but don’t worry—you can still back out before completing the purchase.

How long will it take for my items to arrive?

If your order is in stock, most orders ship within 2–7 business days of purchase. Transit time then depends on the distance from the warehouse and, for freight, on booking a delivery appointment.

For custom, pre-order or made-to-order items, the estimated delivery time frame is listed on the product page. Delivery dates are estimates, so please don't book installation labor until your order has arrived and been inspected.

What happens after I place my order?

As soon as you place your order, you'll receive a confirmation email with your order details—be sure to keep it for your records. Once your order ships, you'll receive another email with tracking information.

For freight deliveries, the carrier will call or text you to schedule an appointment once the shipment reaches their local terminal. Someone needs to be there to inspect the shipment and sign for it. Smaller parcels arrive by UPS or FedEx without an appointment.

Is there a warranty?

Yes. Products purchased through Topture include the applicable manufacturer’s warranty, subject to the manufacturer’s terms. You’ll find the warranty details for each product under the "Warranty" tab on its product page, and we help with troubleshooting and warranty coordination if an issue comes up.

Do you have a showroom?

We don’t have a showroom — we sell online. Our team is available by phone, email and chat to help you compare models, sizes and heaters, and we can send dimensions, installation manuals and electrical requirements before you buy.

Where do you deliver to?

We deliver throughout the 48 contiguous states, with curbside freight delivery for large items. Free shipping and standard rates apply there only. Alaska, Hawaii, Puerto Rico, other U.S. islands and Canada are quoted separately, depending on the brand and model. We can't ship freight or oversized items to P.O. boxes.

Do you ship internationally?

International Shipping

For many products, yes, including to Canada, by custom quote. Email contact@topture.com with the product and your address before you order; availability and cost depend on the brand and model. Any duties, taxes and customs fees are your responsibility.

Shipping to Hawaii, Alaska, and Puerto Rico

Free shipping applies to the continental United States only. Shipping to Alaska, Hawaii, Puerto Rico and other U.S. islands is quoted separately and depends on the brand and model. Email contact@topture.com for a quote before you order.

HUUM UKU Extension Box, a white wall-mounted enclosure with the HUUM logo and cable entries along the top

Your sauna heater wiring and power, done the right way.

  • Secure checkout
  • Authorized retailer · manufacturer warranty