Cast Iron Radiators: Replacing Broken Temperature Control Valves without Draining Water (1970s)

Hello,
in our new apartment in a block of flats we have old cast iron radiators (block from the 1970s). There are no heat allocators on the radiators. Each temperature control valve is broken (probably due to old age) and water is dripping from them, so I wanted to replace these knobs with, for example:
http: // allegro ...
Can such knobs be inserted into old radiators? Can you replace it yourself without draining the water from the entire block?
If they cannot be replaced, what to do with the leaking knobs?

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I deleted the link to the auction
3.1.18. (10.11) It is forbidden to publish information for sources that expire after a certain time (publication of links to pages of a short-term nature).

These are thermostatic valve heads and will not fit. If you can move the valve spindle on the radiator, remove the knob and tighten the gland. If this does not help, unscrew the gland nut, pull out the gland, fill it with e.g. a string with a little grease and fold it, controlling the valve's ability to move the spindle.

First of all, it does not matter if the radiator is cast iron, Favier, aluminum or steel, as long as the SIZE of the new valve (thread diameter and length) is the same as the old one. It is a replacement of the ENTIRE valve, therefore it is NECESSARY to drain the water at least from the riser that supplies the radiator (closing the vertical valves for both supply and return and draining the water from the riser). Means that you can't actually do it yourself (unless you have access to the lift valves, but there may be a "scandal" with draining the water), except when the water is drained in the summer (some cooperatives drain the water from the installation for the summer, in case someone is doing a renovation, but in principle the water should remain in the installation permanently, because this is the case for pipes and radiators - especially steel ones - better). Leaks can be eliminated quite easily. If it is a VERY OLD valve, unscrew the cap nut tightening the gland (of course, first remove the knob and the head cover), pull out the gland with pliers (put the bowl underneath), twist the tow string saturated with thread paste around the valve's spindle, push it deep into it string (it is important that there is a lot of paste there), the gland is pressed in and tightened with this cap nut. In slightly newer (but also old type) valves there is an O-ring, but gouging out the old O-ring with an awl) can cause a strong leak (a large pelvis is necessary), which should be replaced. Valves of this type (especially the oldest ones, sealed with tow soaked in paste) should not be turned too often, because from constant manipulation, leaks form (practically it is best when they are fully turned on and not touched, but it may be in the room "Saudi Arabia" in terms of temperature).

From what you write, I concluded that you have old manual valves that have leaked (similar to this one).
This type of valve cannot be fitted with a thermostatic head, e.g. as you provided in the link. To be able to attach the head, you need to change the thermostatic supply valve (e.g. such as this one)
Unfortunately, if the valves leak, they need to be replaced. I do not know about you, but I had an order in the block to replace the radiator and it was associated with reporting it to the cooperative and obtaining a permit. Then a specialist from that cooperative came and drained the water from the installation because the apartments do not have separate shut-off valves. After my assembly, he came and turned on the water (in 2 days ...) and checked that everything was done in accordance with the notification. I would like to point out that the apartment is ownership. Well, unless it works differently for you.

So it's best to call a plumber to replace the valves in the apartment with thermostatic ones and then I can buy such heads, yes?
It is impossible to replace the entire valves with the method of freezing the pipes so as not to drain the water from the system?
Will such thermostatic heads be successful in old cast iron radiators?
What are the approximate costs of replacing valves and heads with labor? Can water shut-off valves be used to close the valve in the house and replace the radiators at a later time?
I can buy such a valve Link and then replace the head itself?

Freezing the pipes would make it possible to replace the valve without draining the water from the riser. This is done by specialized companies that have equipment for freezing pipes. I do not know whether these pipes can be frozen at all in case of frosts and, consequently, high parameters of the heating medium (the vertical valves would have to be closed). Valves with thermostatic heads are commonly used in cast iron radiators (the installation is often modernized just by replacing old valves with thermostatic ones and the radiators remain the same because they are durable) and work well, although cast iron radiators are characterized by high inertia (large amount of water and the weight of cast iron). ). As for this link, there is an ANGLE valve on it. You have to check (by eye, you can see it from a distance) whether the valve is straight (most often) or angular (they are rarely used).