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Thermostatic Valve Insert for Standard Flows VS1200SX

Thermostatic Valve Insert for Standard Flows VS1200SX

Product Description

The VS1200SX is a thermostatic valve insert for valve bodies with the AT-Concept interface.

It has a presetting device enabling the hydraulic balancing of circuits in which these valves are installed. The AT-Concept is a valve/insert interface used by MNG, Honeywell and Honeywell Home thermostatic valves produced by Resideo and its predecessors since 1974. The VS1200SX mechanically fits in all of these legacy valve bodies. Resideo has developed the SX insert and amended the ATConcept interface, to enable higher nominal flows with thermostatic controls as required by modern heating systems with low temperature setpoints. A perfect mechanical cross-fit of legacy and new inserts and housings is guaranteed. However, only valve housings produced after September 2020 feature the augmented nominal flow. The SX insert is designed and tested for operation in both flow directions. When used in the AT-Concept valves, it operates with low noise in both directions.

Technical Properties

Medium type water or water-glycol mixture according to VDI 2035
Body-head connection M30 x 1,5
Nominal pressure PN10
Max. delta P 1 bar
Pre-settable yes

Insert catridge and plunger made of brass. Return spring, spindle and spindle cap made of stainless steel. O-rings and plunger seal made of EPDM 70. Orifice casing and setting screen made of PPS GF40. Retaining bushing and setting dial made of PBT GF30.

  • Flow rates easily adjustable by a setting key (see Accessories)
  • Proportional flow control characteristic with maximum flow limited to max. 130 % of nominal flow to prevent misbalance during heating of cooled down rooms
  • Quiet operation, including in reversed flow direction
  • Strong restoring spring, which is not immersed in water, ensuring durability of the valve
  • Double O-Ring seal for maintenance-free operation
  • Standard 19 mm hexagon interface
  • Enables valve shut-off with the protection cap (see Accessories)
  • Valve insert fitting the Honeywell Home AT- Concept design, ensuring housing and insert cross compatibility with MNG, Honeywell and Honeywell Home thermostatic valves produced by Resideo and its predecessors since 1974
Closing dimension 11,5 mm
Stroke 0,45 mm
Max. media temperature 130 oC


Product Type Dimensions (mm)
With original AT-concept interface


Single pack in polybag


210 x 150 x 100 mm

Cardboard box of 200 pcs

Accessories and replacement parts


Image Description Product Type Downloads
Metallic presetting key with chrome plating for PI, SX, FX and LX type valves VA8201PI04  
Plastic presetting key for PI, SX, FX and LX type valves and Verafix lockshields VA8201TRV01