Old Cast Iron Radiator Valve: Replacing Heads, Types, Venting Radiators Without Valves

Hello, during the occasion, as I have drained the water from the radiators, I want to replace the heads in the valves, but they are 2 types and the question is whether I will buy them? because I don't want to unscrew and replace the whole valve.

And another question, if I have a radiator without a valve, how to vent it?
CO gravitational

Loosen the screw connection connecting the radiator to the valve.

I'm afraid that there may be a big problem with buying heads for these valves (unless at TOMEX marketplaces - if in Krakow). I see 2 different heads in the picture. One of them can be up to 50 years old (very old model) - the other - certainly 30 years old. I would replace the entire valve. The replacement is simple - you only need to select the size of the valve (the picture shows that these are large diameters - the one on the left picture is probably 1'', on the right it looks like 3/4'' - you need to check it - the valve is always stamped dimension). Gravitational heating requires large cross-sections of pipes and valves.

but I'm afraid that if I move this valve, there will be other threads or cus and pale ass
and what about venting it without a shut off valve?

Air is vented automatically thanks to proper pipe slopes (between the riser and the radiator).

maciekchn wrote:

but I'm afraid that if I move this valve, there will be other threads or cus and pale ass

You take the new valve in your hand and try it on where the old one was. You will need additional elements such as nipples (maybe reducing ones), muffs or reducers. Maybe just an "extension" with the same thread is enough - different lengths are available every 1 cm. There should be so-called black, and if smaller dimensions (lengths) of these elements are required, brass ones must be used.
You twist it "dry" to match the dimensions and thread sizes, and if everything is OK, you mount it on tow and paste. A valve with a half union makes it easy to assemble.
Here I would recommend valves, e.g. herz 3/4 "or 1" with increased flow. In addition, any M30 (M28)x1.5 head.
A challenge for the inexperienced in this matter can be just unscrewing these threaded connections. Maybe it's cheaper and better to hire a professional?

What is the reason for replacing the heads?
If they leak, just clean them of paint and replace the seals.
Just ordinary valve maintenance, why go to the expense and "turn the porches for the worse".

saskia wrote:

What is the reason for replacing the heads?
If they leak, just clean them of paint and replace the seals.
Just ordinary valve maintenance, why go to the expense and "turn the porches for the worse".

These old-style valves tend to leak when you turn them because the gland packing wears off very easily (so they should hardly be used for temperature control). The repair is trivial - unscrew the gland, remove the used gasket, put on a new one (if there is none, it's a string made of tow, saturated with thread paste or tovot), push in, tighten the gland. New types of valves (those for thermostatic heads) almost never leak.

They leak, and I don't know whether to fix it or replace it, I don't use them at all, only when I vent them 1-2 times a year

If it's gravitational CO, then what kind of fungus do you vent the radiators for.
If they actually air, it means that something is wrong in the installation, so remove the cause of the air.

The paint on the unions is intact, so how did you bleed it?

in the ones that I have, I have vent valves at the back, I screwed the heads and vented them and you move the heads a few times and it leaks, already dismantled, and to dismantle it, you have to remove the radiator, for now I have a problem with the purchase, they do not have such a length anywhere.