[Solved] Replacing Broken Heater Knob: Step-by-step Guide, Finding Replacement & DIY vs. Plumber

Hello. I haven't been able to regulate the temperature on my heater for a while.
The knob is broken. Generally it turns about 300 degrees, but the temperature doesn't change. The mushroom is cracked / broken somewhere. I would like to know how to replace it and where to find a replacement. I was looking on the Allegro but there I found some knobs with thermostatic valves.
I would ask for instructions on replacing such a knob as in the photos and a link to the Allegro with such a knob because I did not find it myself.

do you need to call a plumber to replace such a knob?

please help me step by step what to do.

Thank you very much in advance.

This knob of yours looks like a thermostat to me too.

unscrew this nut and the head will come off


enter thermostatic head - on Allegro and there is resistance to it. If you have a company written somewhere on the head, look for this name. Or, unscrew the mentioned nut, take the head to the store and buy the same or similar. Replacing the head itself may not be enough. It's best to swap the heads between the radiators, if you have two of the same, of course, and you'll see what will happen. In the event that another head (normally good) will still not regulate, unfortunately you need to replace the entire valve, and this involves draining the water from the radiators, unless you have additional valves on each radiator, so you only drain the water from one.

and if I unscrew only the indicated cap, I do not have to drain the water? will the water leak anyway?

The water will not leak out. Because you only unscrew the thermostatic head. The valve remains in place.

you helped me thanks a lot. subject to close