LK 550 Mixing Valve


Technical Data

Working temperature              Min. +5° C/Max. +90° C (Min. 41° F/Max. 194° F)

Operating temperature                        Min. +38° C/Max. +65° C (Min. 100.4° F/Max. 149° F)

Max. working temperature     1.0 MPa (10 bar)

Material, valve body               DZR Brass EN 12165 CW602N
Material, sealings                    EPDM


LK 550 is a mixing valve for water heating with a thermostatic element that regulates the supply of cold water in order to achieve the desired temperature. Self-circulation is prevented with a check valve installed in the cold water supply – see under Accessories. Valves with male thread G ½” and 15mm compression fitting have an air vent for simple draining of smaller water heaters.


Arrows on the body valve indicate the direction of the flow:

  • KV = incoming cold water
  • VV = incoming hot water
  • BV = outgoing warm water


When fitting to a male thread connection adapter LK 373 is used – see under Accessories.


When fitted on top of boiler/storage tanks with built-in water heaters the valve should be installed with some space between boiler/storage tank and valve so as not to let the function of the valve be affected by heat radiation.


The valve knob is used to set the desired warm water temperature within the range of 38° C to 65° C (100.4° F to 149° F). The maximum temperature can be calibrated as follows:


Increasing the Maximum Temperature:

Turn the knob anticlockwise to (+). Loosen the screw and move the knob out to the side. Then turn the knob clockwise to (-) without it being engaged. Adjustments are carried out in small steps. A ¼ turn corresponds to approximately 7° C (44.6° F). Reinstall the knob and check that it engages with the teeth. Tighten the screw and then turn the knob to max (+). Max. calibration for increasing the temperature is a ½ turn.


Reducing the Maximum Temperature:

Do the procedure in reverse. Turn the knob clockwise to (-) and the disengaged knob anticlockwise to (+).


Please see video for further information. https://www.youtube.com/watch?v=nJR-DlZuYlE&list=PLCMrvBGaOplpkvlu_zIsW-YZdR_qelvxo&index=19&t=0s