Sealing Leaky Radiator Flare Nut: Effective Steps for Cone Connection Repair

Hello all.
In the summer I did a renovation, so I dismantled all the radiators, after the renovation they returned to their place, one turned out to be resistant - it is the bottom flare nut that is leaking. The connections are cone, I don't know how to seal it.
I would like to add that replacement is not an option - they started to heat up.
If anyone knows, please give me solid advice.
Greetings.

If the tightening itself does not help, then it is necessary to check whether the O-ring is sometimes damaged. If it is damaged, the O-ring must be replaced.
It's best if you give a photo of this screw connection, because there are a lot of them and it is difficult to advise without knowing what type of speech is.

If it is leaking on the thread, nothing can be done without unscrewing it. If at the junction of the cone, you can try to twist tighter.

Hello again, I will try to explain in more detail what this nasty screw connection looks like after unscrewing (maybe for a professional, his photo says something, a visible bowl under it Come on, it's not funny at all) It is an ordinary cone, it does not have any gasket there, just like the screw connections on the top of the radiator do not have it either. For me personally, it is flowing on this cone in a strange way, the radiator is tightened to the maximum (I'm more afraid that I will twist the copper pipe, although I hold the bottom valve with a key while tightening) And here's a huge problem whether it is possible to seal it in some magical way cone (if necessary, I can unscrew the radiator only with which to seal the cone without replacing the entire flare nut so that it lasts, come this heating season. Regards

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here is a picture of it ....


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even a small drop of water is visible

Are you sure it is dripping from the cone?
Check if you have lost or damaged the gasket under the valve cap sometimes. Valves that are closed with an Allen key often let water through and therefore are closed with the cap with the gasket underneath. Maybe this cap is just not tightened.

I sealed it with Teflon tape wrapped around the cone.

I would leave it alone if it drips like 5 cm3 / day, then after some time the so-called The "stone" itself clogs the leak (which was once referred to, I do not know why: with the word "tighten"). Cone screw connections (lapped) are difficult to seal with a flat gasket, e.g. a textolite gasket available in stores. The best for this purpose is a gasket cut from lead sheet , natural leather, 2-3 mm thick, soaked with varnish, or twisted from tow in a secret way known to old plumbers and therefore called: a garland.

If the flare nut did not have a new gasket, the so-called the O-ring, which means that it is to ensure a "grinding" tightness, i.e. both elements are polished in such a way that if tightened sufficiently (but with some moderation so as not to break the thread), it should ensure tightness (even for gas installations). It is not known whether the cone of this flare nut has not been damaged, e.g. by falling on a stone or hitting something with steel or stone (flare fittings are generally brass, so much softer than steel). The finish coat cannot be damaged, otherwise it will not ensure tightness. Maybe (if there was any heating break) you could try to unscrew it and coat the cone with some thread sealing paste. In general, the screw unions should be stored carefully and protected against mechanical damage, because both parts are carefully ground to each other (hence they should not be interchanged with several screw connections).

Hello. What is the problem? I see that you have a return valve and there is probably a supply valve too, so turn off both, drain the water from the radiator and look at the flare nut, if it is damaged on the radiator side, replace it with a new one, and if on the valve side try to insert a thin gasket or like Colleagues Teflon markers above.

krisi3 wrote:

Hello. What is the problem? I see that you have a return valve and there is probably a supply valve too, so turn off both, drain the water from the radiator and look at the flare nut, if it is damaged on the radiator side, replace it with a new one, and if on the valve side try to insert a thin gasket or like Colleagues Teflon markers above.

It seems to me that this is the most sensible answer, unless I do not understand something ... (but if I do not understand something, then my friend also, so there are at least two of us )

Hello!
I will not start a new topic, because I have a similar problem, only with the bottom connection of the Keller V22 radiator. Namely, as in the attached drawing, the radiator started to leak at points A and B, of which I tried to tighten the A with a hexagon socket, but it did not do anything, but I have not moved yet place B. I have no idea how it is sealed and how to seal it so that it lasts until spring. The radiators are 3 years old, funnily enough, leaks often appear when the water in the CO is cold, and with hot radiators the leaks disappear, sometimes there is a leak at point A, but the one from place B is still there.
With what I could somehow seal it. Maybe someone has a cross-section of a similar valve with gaskets?
Thank you in advance for your help

I am afraid that it will not be possible without replacing it with a new one. Just buy a company one, not some trash in a supermarket.

Hello!
These flare fittings were included with the Keller V22 radiators. Which company do you recommend? I will only replace screw fittings in the spring, after the heating season. If I have a charging furnace, the temperature of which ranges between 60 and 80 degrees (on the return I try not to exceed 60-65 degrees, but sometimes it reaches 70 degrees) are there any stronger screw connections for that ??

Keller - what a radiator, such a valve ...
Place "A" can rather be sealed (either tuck the nipple with Teflon / tow, or replace the gasket on the flare nut, if there is one), the problem with place B will be a problem because the sealant has let go and it is a non-replaceable element.
The Honeywell valve will last longer.
Meanwhile, if you do not want to drain the water during the heating season, the only solution will be a bowl under a leaking valve.

Thanks for the help. Now there is actually a container under the valve all the time and it drips from it, sometimes not. You worried me a bit about Keller, because the installers praised the company, describing it as Polish Purmo. Well, I have to look around for such valves and replace in spring-summer.
greetings

There is a way (I checked it yesterday). If the leak is "on the cone" of the flare nut, it could mean that either the cone is damaged or it is not exactly concentric with the other part of the flare nut. You can do this: turn off the valve on the supply and return radiator (necessary, otherwise it will be a deluge), unscrew the nut of this leaky fitting (place a bowl), wipe the cone dry with paper (e.g. toilet paper), wrap the cone with Teflon tape (but of good quality) , professional). Tighten the nut - this will make the tape seal (it will act as an O-ring). After that, open the valves.

Wrapping with a thread does not help, because the thread simply will not fill the leak.
I dare say that in your case the joint was sealed because you cleaned the conical surfaces thoroughly or because you changed their position a bit.

As for the screw unions located at the radiator fittings, there are often delicate leaks on these flare fittings immediately after installing the radiators, because they usually do not have sealing O-rings. These screw connections have spherical surfaces so that the connection can be tight even with slight angular deviations. They often need a few days for them to settle down well and seal.

To sum up, after a few days of heating, they should self-seal and stop leaking. After these few days, you can tighten them with a wrench when they loosen and do not combine with threads or tow.

Hello, buddy, in such cases, copper washers work well. I share the opinion of my colleagues that the best thing to do is to close both valves, supply and return, and let the water out of the radiator, then put the washer and tighten. greetings.

Our colleague Zbigniew is right that most often it is the lack of alignment that makes the valve leaky. In my case, it turned out that the valves under the radiators (the so-called pants) were manufactured by Diamond, after consulting the service and presenting the case, it turned out that there was a period when Diamond had a problem with the centering machine. The service center sent me new valves and took the old ones with them. The problem is now resolved and has not recurred to date.
For my part, I respect Diamond for being able to admit he was wrong. Now I always take valves with an additional cap, which will additionally protect in the event of a slight leakage.