The radiator does not heat up from the middle down

Hello, I have a problem that the radiator does not heat from the middle down, it is a new radiator and the pipes have been pulled from the radiator in another room by a plumber All the radiators in the house are warm from top to bottom only the one made by the plumber does not heat up completely Please for help what it could be

Air in the air. Has an air vent at the end of the heater?

It can even be partially curled, the heat effect is similar. If venting does not help, there is an adjustable orifice under the thermostatic head, maybe it needs to be unscrewed?

There is air in it, the vent is mounted on the top, on the opposite side of the radiator supply, depending on the type of vent installed, press the lever or loosen it until water starts flowing without air bubbles.

For deaeration to be effective, it would be necessary to turn off the inflow to this radiator, and venting to be done only when the radiator is "powered" by the drain. The point is that the water pressure to the radiator should come from the bottom and push the air up.

If the gray is completely cold only at the top and the bottom is completely cold, there is probably no air in the air (when there is air in the first 2-3 ribs - from the supply side, and the rest is cold), but too little flow. The reason for this may be either excessive clogging of the radiator (initial setting set too low or - if it were an old type valve - the use of an orifice with too small an opening), fouling of the orifice, or too small cross-section of the supply and return branches. If the other radiators work very well (too well) and this one is weak, maybe the other radiators need to be choked a bit. In any case, the problem is with the flow.

Venting, unfortunately, does not give anything, the inlet end is a new radiator at the bottom heats up but very slowly it takes him an hour, maybe more than to be slightly warm, and 2-3 and warm

PITERRR wrote:

Air in the air. Has an air vent at the end of the radiator?

When the whole mountain heats up, there is no air in it, but the flow is too low.
If the early one was fine and nothing was changed in the installation, the pipes were clogged (most often flanges) and the radiator was eventually muddy.

Close all the radiators and leave this unscrewed, it may actually be clogged.