ESBE VTS522 solar thermostatic valve with external G thread (ESBE series photo)
ESBE VTS522 with R ¾ adapters and check valves
Front drawing of the ESBE VTS522 valve from the VTA520 and VTS520 series

ESBE VTS520 thermostatic mixing valve for solar domestic hot water

Model
Regular price€358,38
/
Tax included. Shipping calculated at checkout.

  • 4 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.

You may also be interested in...

ESBE VTS520 thermostatic mixing valve for domestic hot water in solar installations

The ESBE VTS520 blends hot and cold water to deliver domestic hot water (DHW) between 45 and 65 °C when the cylinder is heated by solar collectors and can reach high temperatures. At Q-Tech we fit it on the DHW outlet of the pre-assembled plant room, tested in our workshop before it reaches your site.

Summary

Type3-way thermostatic mixing valve for domestic hot water
Brand and modelESBE VTS520 series (VTS522)
UseDHW in solar installations, with or without circulation, according to ESBE
Setting range45 to 65 °C
Water temperatureUp to 110 °C continuously and 120 °C temporarily
SafetyShuts off the hot water if the cold water supply fails
FlowKvs 3.0 to 3.5 m³ per hour
Power supplyNone: thermostatic control without electricity
Q-Tech installationIntegrated and tested in the Q-Tech pre-assembled plant room

What is the ESBE VTS520?

The ESBE VTS520 is a thermostatic mixing valve for domestic hot water in solar installations that accepts water up to 110 °C continuously, according to ESBE. An internal thermostat adjusts the mix without electricity. It is fitted at the outlet of the solar cylinder.

What problem does it solve?

In summer, solar collectors can heat the cylinder well above the temperature of use. The VTS520 adds cold water to deliver a safe temperature at the taps, from 45 to 65 °C.

If the cold water fails, the valve shuts off the hot water and prevents a scald. A conventional DHW thermostatic valve such as the VTA320 accepts up to 95 °C according to ESBE, which is why the VTS520 is chosen for solar.

Technical data

Pressure classPN10 (working pressure 1 MPa)
Maximum differential pressure0.3 MPa (3 bar) when mixing
Media temperature110 °C continuously; 120 °C temporarily
Temperature stability±4 °C, with constant pressures, a minimum flow of 9 litres per minute and 10 °C between hot inlet and mixed outlet
Safety functionHot water shut-off if the cold water fails
MediaDomestic water, closed systems and water with up to 50% glycol
ConnectionsExternal thread G (ISO 228-1); adapter version R ¾ (EN 10226-1)
MaterialDezincification-resistant brass (DZR)
ConformityPressure Equipment Directive (PED), article 4.3; no CE marking

Models and data by variant

ModelConnectionRangeKvs (m³ per hour)Net weightReferenceEAN
VTS522G 1 external45 to 65 °C3.20.86 kg317201007330193040662
VTS522G 1¼ external45 to 65 °C3.50.95 kg317203007330193040686
VTS522 with adaptersR ¾ external45 to 65 °C3.01.22 kg317205007330193040709

Compatibility and limits

  • The adapter version includes two check valves, one for hot and one for cold water, according to ESBE.
  • Below 9 litres per minute, the ±4 °C stability is not guaranteed.
  • Maximum differential pressure of 3 bar between hot and cold water, according to ESBE.
  • ESBE also makes a 50 to 75 °C VTS522 that is not on this page.
  • No CE marking: it is pressure equipment under article 4.3 of the PED.

When this product is not the right choice

If the water does not come from solar collectors and stays below 95 °C, the ESBE VTA320 and VTA520 for domestic hot water does the same job with more connection sizes.

Frequently asked questions

Which model do I need?

It depends on pipe size and flow: G 1 with Kvs 3.2, G 1¼ with Kvs 3.5 or the R ¾ adapter version. Send us your outlets and pipe size and we will tell you the model.

What is the difference from the VTA320?

The temperature it accepts. The VTS520 works with water up to 110 °C continuously and the VTA320 up to 95 °C, according to ESBE.

What does the adapter version include?

The R ¾ adapters and two check valves, one for hot and one for cold water, according to ESBE.

Can I install it myself?

It is not advisable: a professional should install it, following ESBE's instructions. Q-Tech delivers it fitted in the plant room or installs it with an Expert Technician.

What is the delivery time?

We have it in stock in Málaga and dispatch it as soon as we confirm your order.

Q-Tech installation and support

Q-Tech fits the VTS520 at the solar cylinder outlet in the pre-assembled plant room: assembled, set and tested in our workshop, it arrives ready to connect. You can book workshop pre-assembly, an on-site hourly Expert Technician or a technical call to choose the model. See also our solar thermal range or message us on WhatsApp.

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.

This site is protected by hCaptcha and the hCaptcha Privacy Policy and Terms of Service apply.