I'm unsure of how to remove the head of this old TRV. It looks like part of it has been removed already. I haven't tried removing or unscrewing anything yet.

front side above


It appears to me that the power head is held on to the valve body by the union nut just beneath the head. Water pump pliers should be able to loosen that nut. Be sure to use back pressure. To loosen turn CCW. Good Luck.

  • Good answer, but you might explain "back pressure"; I presume you mean "if you're applying lots of torque in one direction, you need to support the T with a wrench pulled the other direction". – Daniel Griscom Feb 12 at 0:18
  • Yes, hold the body of the valve with a second pair of pump pliers. Apply equal pressure in both directions until the union nut breaks free. – Paul Logan Feb 13 at 23:51
  • ... with 5k+ reputation, you surely know it's best to include this info in the answer body, don't you? – Daniel Griscom Feb 14 at 1:29

It best to open the valve fully before undoing the union below the actuator. This is a thermostatic valve and upon reaching temperature pressure is applied downward to the valve concealed in the 90° fitting. It will be easier if the radiator set point is set high, allowed to warm and then just before removal set to the lowest setting. You can often undo the union by hand by using this method.

Nut and direction enter image description here

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