Bleeding Radiators: Proper Venting Techniques, Screw Positions (A, B, C), & Ideal Temperature

Hello everyone,
I have never vented radiators and I want to know if I am doing it right. The photo shows one of the 4 radiators in the apartment, but the problem concerns everyone - only the upper half of the radiator is hot, the lower part is cool, summer. I unscrewed the screw (A) a little with a screwdriver, but instead of air, water started to pour in a trickle. And I am convinced that there is a lot of air in circulation there. Am I doing everything right - or maybe I should unscrew the B spot slightly with the pliers or the C spot wrench with the Allen key? And should I do venting at 50-60 degrees hot? radiators or cold? Thanks for the help

PS Can aerated radiators be the reason why they take a long time to heat up to the temperature specified on the gas furnace?

Bleeding is much better on a cold radiator, and additionally, the pump, if it is in the installation, does not move the water. Bleeding on this radiator is done using the screw (A). But you have to know that the radiator is always much warmer in the mountains than below. Aired radiators do not heat up, but with long heating, it's something wrong. Maybe there are air in the pipes at the outlet of the stove?

stanislaw1954 wrote:

Maybe there is air in the pipes leaving the stove?

Can you check it somehow?

If there is air in them at the exit of the furnace, the whole installation will rather not "start". Or maybe there are vent valves, just unscrew it to find out.

The first rule of venting radiators: close the valve on the radiator!
Bleeding works by pushing the air out through [A]. To push them out, you must prevent fresh water from flowing through the valve {red}. Air MUST BE forced out by water that enters from below [C] by opening [A] and closing the valve.



Bleeding without closing the valve is pointless, as water will always flow out and air will remain in the radiator.
You vent as long as you hear the air hissing. ONLY water must go. While venting, you can hit the radiator with your hand, or the air bubbles will break away from the nooks and crannies. You check whether it is deaerated by hand: you turn [A] and open the valve. After some time, if point [A] will be of a similar temperature as the inlet at the valve, the matter is closed. If not, continue venting. And so on.
The bottom is ALWAYS cooler than the top - this is the outlet after all.

Thank you, gentlemen, for your help. Tomorrow I will test and write if I was successful.

Wow, new venting technique. Bleeding consists in unscrewing the vent and that's it. It is important to ensure that in the open system the water level is always above the highest radiator (we also allow it every now and then), while in a closed system we keep an eye on the pressure and vent the radiators from the lowest to the highest. According to the law of connected vessels, water, either at the bottom or at the top, will flow into the radiator and replenish it. It will definitely not levitate from the red point to the A point avoiding the bottom.
Your problem is not about air in the radiators, because they warm you up, which means that the water is there. The problem is that the flow of medium through the radiator is too low. Check that the return valves, aka shut-off valves, in point C in your photo, are turned to the maximum (and they should be), then turn off the supply valves on radiators that heat well. These laggards you write about should start moving. This will be proof of my theory. If it is confirmed, send me the info, preferably with a photo of the type of supply valve next to the radiators, I will paint a solution for you. Greetings.

Polon will be experimenting tomorrow and will write tomorrow what the results will be. Thanks for writing.

Polon27 wrote:

Wow, new venting technique.

Not new, but very old. I always use it and I have never (!) Had problems with subsequent heating. In addition, you can also vent the radiator WITHOUT a vent - does your colleague know about this?
I just described how I do it and always with a positive result - you can use it, but you don't have to (if someone doesn't want to).

Well, this method is actually very old, but it was most often used in high-pressure systems and the screw connection of the supply valve was always unscrewed. Maybe I read it too quickly, but I saw no mention of it there. This can also be done with the help of an air vent, especially if someone inexperienced does it.

Hello
I tried the given methods (I had vented the radiators before)
My problem is as follows. Air vents (I have aluminum radiators with a vent as in one of the first posts) do not work, i.e. I unscrew them (even to the end) and nothing, neither air nor water escapes. I have an apartment above two apartments. On the one hand, the radiators are ok, and on the other, they have air in them (only part of the radiator heats up, but it is impossible to bleed it)
How to make it work? Thank you in advance for your answer.
greetings

Jaros12345 wrote:

Air vents (I have aluminum radiators with a vent as in one of the first posts) do not work, i.e. I unscrew them (even to the end) and nothing, neither air nor water escapes.

It may be that the openings in the valves are clogged or that the water level in the system is low.

Jaros12345 wrote:

Hello
I tried the given methods (I had vented the radiators before)
My problem is as follows. Air vents (I have aluminum radiators with a vent as in one of the first posts) do not work, i.e. I unscrew them (even to the end) and nothing, neither air nor water escapes. I have an apartment above two apartments. On the one hand, the radiators are ok, and on the other hand, they have air in them (only part of the radiator heats up, but it is impossible to bleed it)
How to make it work? Thank you in advance for your answer.
greetings

If no water is flowing from the vents then:
-check the pressure in the installation to see if you should have water at your level.
-Which part of the radiator gets hot ?.
- it is possible that the vents have become clogged, try to loosen the flare on the supply pipe (upper hot), and in this way vent.
greetings

Take a 22 mm ring spanner and gently flush the entire vent, it is on the rubber gasket and nothing should happen. Remember to turn off the pump.
It may be that the openings in the valves are clogged, or the water level in the system is low. [/ Quote]
if the water level was too low, the radiator would not heat up at all and part of the radiator would heat up.

Coming back to the first post, if the entire top of the radiator heats up and the bottom is completely cold, there is no air in it, but a poor flow through the radiator (muddy orifice, silted twig, too small orifice cross-section, incorrectly set initial setting, etc.). It is especially troublesome when the radiator is high (as shown in the photo), because then the heating is at the height of the upper body (and even the head when sitting), and it is cold from the waist down (which is why it is better to give lower and longer radiators - the heat always rises). If water flew from the vent, and not air, it also means that there is no air in the radiator (but the supply valve is always turned off for venting).

gersik wrote:

Remember to turn off the pump.

And Jaros12345 mentions something about the pump? Is it at all? It would be good if he wrote something more about his installation, or showed some photos, especially from the part with which there are problems.

Thank you so much for the fact that in fact there is not much water in the installation, so I let it be warmer for everyone in the block. Thank you and best regards.

Hello,

I will dig out the topic because I have an additional question.

I bought a flat in a 30-year-old block, the last - 15th floor. When I bleed the radiator, first the air comes out, and then the mixture like a turbulent Coca Cola from a slightly unscrewed bottle. I have already dumped the amount of 0.5L twice and each time the operation helps for half a day. After that, the radiator becomes noisy and cooler. Bleeding according to the instructions. This applies to two heaters from the apartment.

I read that the water should run in a calm stream, not under such high pressure, and should generally run until the water calms down. My question is, since I cannot refill the water in the system, what is the risk of draining liters of water?

Of course, I will report it to the administration, but they will probably not give a shit before Christmas

kauczukwwa wrote:

My question is, since I cannot refill the water in the system, what is the risk of draining liters of water?

In extended installations (let's call it, for example, block installations), the water loss is usually replenished automatically, so you risk nothing.

stanislaw1954 If you usually type, write that you USUALLY risk nothing. In the block where I lived, gentlemen had to come and replenish.

FOSGEN1 wrote:

gentlemen had to come and replenish.

A strange side. I always vented many times myself, I even drained a few liters before it started to heat up and somehow nobody added anything. In any case, I don't know anything about it, and it always ended up heating the radiators properly.

FOSGEN1- that's why I wrote it usually, because exceptions do happen, an example of which is even your block.

Gentlemen, I will step up not to do a new topic: can replacing manual vents (such as a key) on old, cast iron radiators with newer, automatic ones, somehow negatively affect anything? A lady from the cooperative today advised me against this operation, warning me that the manual ones are better and "wished patience" in everyday running with a cloth and a bucket while venting. I live on the top floor of a large, 15-story block of flats.

m1ch wrote:

can replacing manual air vents (such as a key) on old, cast iron radiators with newer, automatic ones, somehow negatively affect anything?

It won't. It happens that with time they may not stick, i.e. leak.

stanislaw1954 wrote:

It won't. It happens that with time they may not stick, i.e. leak.

Thank you for your answer. Mr. Stanisław, maybe that's what the woman from the cooperative meant ...? "Safety" of residents of lower floors and minimizing the risk of flooding at the expense of someone else's living comfort. Is there a real risk of flooding or is it just a small amount of water being spewed out with the air?

m1ch wrote:

Is there a real risk of flooding or is it just a small amount of water being spit out with the air?

Rather dripping, small amounts.

Hello. I have a problem with heating in the apartment on the top floor (3) I have the same heaters as in the first post. The water supply pipe for heating the apartment is warm, but all radiators are cold. I vented. There is something of this air that comes down from everyone, but still nothing warms up.

I presume you have community / district heating.

The heaters suddenly stopped heating? How much time do you live in this apartment?

Do the radiators have thermostatic heads?

Have you changed anything recently on radiators / heaters?

Are the radiators cold all the way up or is the top warm and only the bottom cold?

I am asking because there can be many reasons. Found a thermostatic valve that does not open despite opening the head itself. Central heating pump run too low for the entire block. Too little water in the system (and you live the highest). Twisted returns on radiators or muddy.

If there was not enough water in the system, you might also hear a hiss while venting, but the air being sucked in through the vent.

As you can see a lot of guesswork, without more information, we can only fortune.

The block was renovated a few days ago. Pipes were replaced from what I live for a long time, the heads were ok and all at once would not break. Yesterday I was venting and the water came out just like from loose champagne and on both sides of the heater you could hear gurgling. I poured an average of 600 ml of water from each radiator and nothing still cold. Feed tube slightly warm at the inlet, cold at the outlet. Valves open. Today I called the cooperative in the morning. You can see something happened in the morning because there is a hot pipe at the exit of the cold at the entrance to the apartment. I started to drain again, I dropped 600 ml and nothing is pouring water and I can hear a hiss, from time to time it shoots like a geyser and continues to fly normally with a hiss under quite high pressure. I'm not sure how much water I can pour so I don't make a comedy. Could thermostatic heads be broken by flushing the water? Yesterday, at the first discharge, I started too quickly and forgot to turn on one radiator. Whether to drain the water all the time on the closed head or to drain the cup. Unscrew it for a moment and let it run again until it hisses no more.

This bubbling like champagne shows the presence of air, which probably goes from the entire riser to this radiator (it is the most in the top floor, because air is lighter than water and goes up). It is not known whether all tenants had the valves on the radiators unscrewed when filling the installation after renovation (it could have been hot, they turned off and, as a result, when filling the installation, the air was not removed because the closed valves blocked them). Then it cooled down, they turned on the valves and the air could go to the radiator on the top floor from the air in the radiators. If the radiator is cold despite venting (and the supply pipe hot), there may be very little (almost zero) flow through the radiator (so little that the water cools down immediately). You have to see what is available after removing the thermostatic head. As this is the top floor, setting a larger preset will not affect the heating of other floors. If the thermostatic valve is Danfoss, no special tools are needed (worse when it is Herz, as changing the setting requires special service tools). Is it in Krakow (KrK written)? Which street. Maybe close to me (possibly I would come and see - I do not have this special instrument for Herz setting, but I have the basic tools used by installers).