Viessmann ViCare ZK03838 underfloor heating thermostat open, side view
Viessmann ViCare ZK03838 underfloor heating thermostat open, front view
Viessmann ViCare ZK03838 underfloor heating thermostat closed

Viessmann ViCare ZK03838 six-zone underfloor heating thermostat

Regular price€375,56
/
Tax included. Shipping calculated at checkout.

  • 3 in stock
  • Backordered, shipping soon

At Q-TECH, we apply the same clear rules for everyone: the law protects you, and when applied correctly, it protects us as well. By processing your purchase, you accept our General Terms and Conditions of Sale. If you are purchasing as a consumer (B2C), nothing stated herein limits the rights granted to you by mandatory law (RDL 1/2007, TRLGDCU): the 3-year legal warranty of conformity and the right of withdrawal under the terms and with the exceptions legally provided, which are detailed below. References to "B2B" apply only to businesses and professionals.

Your guarantees

  • Rights intact: 14 days of withdrawal from receipt for most products—subject to the legal exceptions you will see below, such as goods made to your specifications—and a 3-year legal warranty of conformity, under the terms of the TRLGDCU.
  • Conformity with the description: we guarantee that the equipment will correspond to the published technical description and what one could reasonably expect from it (arts. 115 et seq. TRLGDCU). Images and videos are for guidance only: the manufacturer may supply a more recent revision of the product or introduce minor aesthetic, packaging, or firmware changes, without this constituting a lack of conformity as long as the described characteristics and performance are maintained.
  • Traceability that also protects you: we document the condition, serial number, and seal of each piece of equipment upon shipment, and we video-record the opening of returns; this is your proof of the condition in which the goods were delivered.

Responsible use and your part

  • If you are thinking of returning it, keep it as you received it: without installing or activating it, with its seals, accessories, and packaging intact. This is how to ensure a full refund, without deductions.
  • Handling that exceeds inspection reduces value: handling the equipment beyond what is necessary to verify its nature and operation may result in a real, assessed, and case-by-case justified deduction (art. 108.2 TRLGDCU), never a fixed percentage. In particular: activating or registering the serial number, linking it to a manufacturer's account or app, circulating water through hydraulic equipment, unsealing probes, or installing software or consumables. Initial inspection of the product does not lead to a deduction.
  • The same item must be returned: withdrawal requires returning the supplied unit. Different equipment, or equipment with prior use, age, or wear prior to purchase, does not constitute a valid withdrawal.
  • Installation and cybersecurity, shared responsibility: this is technical hardware; you are responsible for correct installation, credentials, patches, and backups, while we deliver a compliant product. Q-TECH is not liable for damages resulting from poor installation, incorrect configuration, or omission of patches by the customer or third parties (in B2C, without prejudice to the legal warranty and liability for intent or negligence, arts. 86 and 130 TRLGDCU).
  • Delivery of bulky goods: delivery is made to the curb. B2C: transport risk is ours until physical delivery (art. 66 ter); we recommend noting visible damages on the delivery note and notifying us of breakages within 24-48 hours with photographs to activate the insurance. B2B: inspection and notation on the delivery note are mandatory; hidden damages must be reported within 24 hours (art. 366 CCom). Unjustified rejection or incorrect shipping information will entail the actual outbound and return costs (approx. €85-550 for heavy machinery).

Made to your measure (Advanced Pre-Assembly)

  • If your order includes equipment, racks, hydraulic assemblies, or technical rooms made or configured according to your specifications (permanent joints, custom cuts or wiring, parameterization, pressure testing), these are custom goods without the right of withdrawal from the conclusion of the contract (art. 103.c TRLGDCU; CJEU Case C-529/19), which is informed before purchasing and documented in the signed Order Note. A test you request without permanent modification retains your right of withdrawal, with only the actual loss of value caused by that test being deducted. Would you prefer to receive it tested, configured, and ready to connect, without assuming these risks? Contract our Advanced Pre-Assembly or the prior technical audit.

If you are purchasing as a business or professional (B2B)

  • The transaction is governed by the Commercial Code: firm sale, without the right of withdrawal; notification of defects within 4 days (apparent) / 30 days (hidden), arts. 336 and 342. Q-TECH acts as a distributor and excludes indirect damages, loss of profit, and data loss, limited to the price of the equipment, without prejudice to the manufacturer's commercial warranty.

Product warnings v1.0 · June 2026. Information summary; the complete and binding conditions are those published at q-tech.es.

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ViCare underfloor heating thermostat to control up to 6 zones from your phone

The ViCare ZK03838 underfloor heating thermostat from Viessmann drives the actuators on your underfloor heating manifold and controls each zone from the ViCare app. Q-Tech wires it at the manifold, pairs it with the sensors and completes the configuration and pre-commissioning check through an Expert Technician.

Summary

TypeZone controller for underfloor heating with low-power radio
Brand and modelViessmann ViCare, reference ZK03838
UseRoom-by-room temperature control for underfloor heating
ZonesUp to 6 zones and 18 thermal actuators at 230 V
SensorsOne ViCare climate sensor per zone, sold separately
Compatible withViessmann heat generators with One Base and built-in communication module (for boilers, Vitodens 200-W B2HF, B2KF, B2HG and B2KG) or the Vitoconnect OPTO2
Power supply230 V, 50 Hz, 4 W
Q-Tech installationOn-site hourly Expert Technician: wiring, pairing and zone-by-zone test

What is the ViCare underfloor heating thermostat?

The ViCare underfloor heating thermostat from Viessmann is a zone controller that drives up to 18 actuators according to each room's temperature. It receives that temperature by radio from the ViCare climate sensors. It mounts on the wall, next to the manifold.

What problem does it solve?

Underfloor heating without zone control heats the living room and an empty bedroom alike. The ViCare thermostat opens and closes each circuit according to its sensor and schedule, with zone control from the app.

Viessmann states that with ViCare thermostats on every emitter connected to the heat generator, hydraulic balancing is automatic, with TÜV certification.

Technical data

Power supply230 V, 50 Hz
Power consumption4 W
Outputs6 outputs for thermoelectric valves, 230 V relay, 2 A continuous (max. 6 A)
Additional output1 volt-free contact for pump or valve, max. 6 A
Compatible actuators230 V thermal, normally closed
Radio2.4 GHz, encrypted
RangeUp to 14 m through walls, depending on thickness and structure
Dimensions (width × height × depth)312 × 99 × 60 mm
ProtectionIP22D, class II
Operating temperature+5 to +50 °C
Box contentsThermostat, external antenna with 1.3 m cable, contact sensor with 1.8 m cable, 1.2 m cable with connector, tool and fixing kit

Compatibility and limits

  • Needs a gateway: Viessmann heat generators with One Base and built-in communication module (for boilers, Vitodens 200-W B2HF, B2KF, B2HG and B2KG) or the Vitoconnect OPTO2.
  • One climate sensor per zone: the ViCare ZK03839 sensor is sold separately.
  • 230 V thermal actuators, normally closed; Viessmann sells the 7750202 actuator.
  • Includes frost protection and an anti-scale function for the valves.
  • The 230 V connection must be done by a qualified professional.

When this product is not the right choice

  • Radiator heating: room control is done by the ViCare radiator thermostat.
  • You only need a room control for a Vitocal 150-A or 250-A heat pump: the Vitotrol 300-E or the Vitotrol 100-EH.
  • Underfloor heating from another brand with its own control system: keeping that brand's control is advisable.

Frequently asked questions

How many sensors do I need?

One per zone. With 6 zones, 6 ViCare climate sensors.

Does it work with my current actuators?

Yes, if they are 230 V thermal actuators, normally closed. If you are not sure, send us a photo of the manifold on WhatsApp.

Does it work without a Viessmann boiler?

Yes, with the Vitoconnect OPTO2 as the gateway, even with no heat generator connected.

Can I install it myself?

Only if you are qualified to work on 230 V. Q-Tech wires it, pairs it and tests each zone with its hourly service.

What is the delivery time?

It is in stock at our warehouse, as the note at the bottom explains.

Q-Tech installation and support

A Q-Tech Expert Technician carries out the installation and pre-commissioning check: mounts the thermostat next to the manifold, wires the actuators, pairs the sensors and leaves every zone working in ViCare. Book it with the on-site hourly Expert Technician service; for prior questions, use the remote technical call. See the other components in Viessmann ViCare and Control.

Documentation

Availability and lead times: this item is in stock at our warehouse. Occasionally, depending on the time of year, the stock update may contain an error. If no units are available when you place your order, we will order it urgently and inform you immediately of the updated delivery time.

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