ESBE VTC312 load valve with external G 1 thread
ESBE VTC311 load valve with internal Rp ¾ thread
Front drawing with dimensions of the ESBE VTC300 load valve
Side drawing of the ESBE VTC300 load valve

ESBE VTC300 thermostatic load valve for biomass boilers

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Regular price€248,44
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  • 4 in stock
  • Backordered, shipping soon

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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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ESBE VTC300 thermostatic load valve for biomass boilers up to 30 kW

The ESBE VTC300 keeps the return temperature to the solid fuel boiler high while it loads the accumulation tank, with no electricity and no adjustment. At Q-Tech we fit it in the pre-assembled plant room, tested in our workshop before it reaches your site.

Summary

Type3-way thermostatic load valve
Brand and modelESBE VTC300 series (VTC311 and VTC312)
UseReturn protection of solid fuel boilers and loading of accumulation tanks, according to ESBE
Boiler outputUp to 30 kW
Opening temperature45, 55 or 60 °C depending on the model
ConnectionInternal thread Rp ¾ (VTC311) or external thread G 1 (VTC312), DN 20
Power supplyNone: an internal thermostat controls the mixing
Q-Tech installationIntegrated and tested in the Q-Tech pre-assembled plant room

What is the ESBE VTC300?

The ESBE VTC300 is a 3-way thermic valve that protects the boiler from cold return water, according to ESBE. It is installed in the return pipe to the boiler and works in any mounting position.

What problem does it solve?

When water returns cold to a solid fuel boiler, combustion does not reach its temperature and tar and condensation build up. ESBE states that a high, stable return temperature gives higher efficiency, less tarring and a longer boiler life.

The VTC300 starts to open port A when the water at outlet AB reaches its opening temperature, and fully closes port B when port A exceeds it by 10 °C, according to ESBE. It regulates on two ports, so it works with no adjustment valve in the bypass.

Technical data

Pressure classPN10
Maximum differential pressure100 kPa (1 bar) mixing; 30 kPa (0.3 bar) diverting
Media temperatureFrom 0 to 100 °C
LeakageA to AB, tight sealing; B to AB, maximum 3% of Kvs
Rangeability Kv to Kv minimum100
MediaHeating water to VDI 2035, water with up to 50% glycol and water with up to 28% ethanol
ConnectionsInternal thread Rp (EN 10226-1) and external thread G (ISO 228-1)
MaterialDZR brass CW625N, resistant to dezincification
DimensionsA 70 mm, B 42 mm, C 42 mm, D 46 mm
ConformityPressure Equipment Directive (PED), article 4.3; no CE marking

Models and data by variant

ModelConnectionOpening temperatureKvs (m³ per hour)Net weightReference
VTC311Rp ¾ internal45 °C ±2 °C3.20.53 kg51000100
VTC311Rp ¾ internal55 °C ±2 °C3.20.53 kg51000200
VTC312G 1 external45 °C ±2 °C3.20.51 kg51001500
VTC312G 1 external55 °C ±2 °C3.20.51 kg51001600
VTC312G 1 external60 °C ±2 °C3.20.51 kg51001700

Compatibility and limits

  • For boilers up to 30 kW, according to ESBE.
  • Maximum differential pressure of 1 bar when mixing and 0.3 bar when diverting.
  • With 30 to 50% glycol, the maximum valve output drops by 30 to 40%, according to ESBE.
  • The circulation pump is not included; ESBE asks for it to be sized with the pressure drop of the valve and the rest of the system.
  • The opening temperature is fixed; it is changed by replacing the thermostat with an ESBE VTC931 thermostat of another temperature.
  • ESBE recommends fitting shut-off valves on the connections to make maintenance easier.
  • No CE marking: it is pressure equipment under article 4.3 of the PED.

When this product is not the right choice

ProductWhen to choose itMaximum boiler outputPump included
ESBE VTC500 load valveIf your boiler is above 30 kW150 kWNo
ESBE LTC300 load unitIf you want the valve and a high-efficiency pump in one unit50 to 90 kW depending on the opening temperatureYes, 6 m

Frequently asked questions

Which opening temperature should I choose?

The one your boiler manufacturer requires for the return: 45, 55 or 60 °C. If you tell us your boiler model, we will tell you which valve you need.

What is the difference between the VTC311 and the VTC312?

Only the connection: the VTC311 has an internal Rp ¾ thread and the VTC312 an external G 1 thread. Both are DN 20 with Kvs 3.2.

Can the opening temperature be changed?

Yes, by replacing the thermostat with an ESBE VTC931 of another temperature. The ESBE video in the Documentation section shows the change.

Does it include the pump?

No. If you prefer the valve and the pump in one unit, the ESBE LTC300 load unit integrates both.

Can I install it myself?

It is not recommended: it should be installed by a professional, 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 VTC300 in the pre-assembled plant room: assembled and tested in our workshop, it arrives ready to connect to the boiler and the tank. You can book workshop pre-assembly, an on-site hourly Expert Technician or a technical call to choose the model. See also our biomass collection 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.

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