Central Heating Pump Air Issue: Electronic Pump Installation, 75 Degree Temperature & Radiators

I have a problem with the electronic central heating pump. Previously, the pump was installed on the return, but this system did not work well, so this year it was installed on the power supply. My problem is that at temperatures above 75 degrees on the stove, the pump airs out and slows down to the lowest power, and thus the temperature on the stove increases because only 2 radiators heat up. There is no vent at the pump, and it does not force it to work faster when there is air in it, so the only way is to loosen the screw connection behind it or try to lower the temperature on the stove. When looking for a solution, I installed a separator, but it only helped with the occasional squeaking of the pump. I have no idea what to do, so as not to wonder every time I am not at home or the pump sometimes did not want to slow down, so I am asking you for help, which may be the reason.

I had a similar problem. On the knee in front of the pump, I put a tee to which I screwed a 15 cm tube with an automatic air vent.
Until today, everything is working ok.

jaras99 wrote:

I have a problem with the electronic co pump

This is not a problem with the pump and the installation.
The installation is muddy or the filter is blocked, if there is one.
The question is, why do you keep the temperature above 70 degrees?
In an open system with the pump mounted on the supply at a temperature of about 70 degrees, this phenomenon will always occur because there is no way to completely remove the air from the system.

hemicznyali wrote:

jaras99 wrote:

I have a problem with the electronic co pump

This is not a problem with the pump and the installation.
The installation is muddy or the filter is blocked, if there is one.
The question is, why do you keep the temperature above 70 degrees?
In an open system with the pump mounted on the supply at a temperature of about 70 degrees, this phenomenon will always occur because there is no way to completely remove the air from the system.

Is it an open or closed system?

The horizontal section of the installation, where the pump is located, forms the so-called air trap. There is an unnecessary elbow behind the pump [those directed downwards.
Install an air bleed next to the pump, you can replace it with that 1/2 inch elbow with plug.

Unscrew this knee with manual air vent behind the pump and install a 10-15cm pipe and then install an automatic air vent on it should help. with the pump, we installed automatic vents if the pipes ran horizontally, if vertical, then not.

daro31ie wrote:

Is it an open or closed system?

And that's a good question, it should be an open-ended layout from the photos you can deduce that it is.
And that's not the most important thing.

jaras99 wrote:

Previously, the pump was installed on the return, but this system did not work well,

First, we need to find the reason for the fact that when the pump was on the return, the system did not work properly, or actually, as you can guess, it did not work.
If we find the cause of this condition, the problem will resolve itself, but for it to happen, more installation data is needed.
These few photos tell us nothing.

Added after 10 [minutes]:

Kraniec_Internetów wrote:

Most modern pumps have a self-venting system that only works properly when the pump is mounted vertically and the water is flowing upwards.

Unfortunately, this claim is wrong, at least in this case, because this pump does not have self-venting. Pumps with a separator have an automatic air vent.

The author probably built this installation himself. The installation is completely messed up, a book example of how it's not done.
There will always be air in the pump as the pipework creates a siphon at the highest point. Manual air vent installed inconsistently with the art (not performed on horizontal pipe sections). The automatic air vents in front of the pump proposed earlier is a mistake, because they can cause air to the system (draw air).
Same expansion vessel. A valve is installed on the expansion pipe, but there is no safety pipe.
I would also like to point out that there is no ventilation grille in the room - it must be on the ventilation chimney located in the immediate vicinity of the boiler's smoke duct, the chimney ventilation duct cannot be used to ventilate other rooms.

In your case, this air separator should be installed horizontally in front of the pump.
Move the pump to the left, the separator horizontally behind the pump.
There should be a strainer in front of the pump, there is no check valve and no shut-off valve behind the pump.

It could be cavitation. Try to reduce pump power at higher furnace temperatures.
Even at 70 degrees on the stove, water can boil around the pump due to the sudden change in pressure, steam is formed and you have a problem. It is very hard to fight. Not even a thermometer
in front of the pump / constriction / may cause this.

Thanks to everyone for the advice. Before installing the separator, the pump was mounted vertically and the effect was the same. The installation was built by some master many years ago, a manual air vent was added this winter when installing the separator, but in fact I agree that it was not a good idea. The expansion vessel has long been to be replaced and hence the valve. I sometimes increase the temperature because I have a problem with the last two heaters, which only heat up about 15 cm from the top, even after all other radiators are turned off and do not heat my rooms. Do you think that it may be a problem with too low pressure or more with fouling of the installation?

The valve is, of course, unscrewed, It is founded because it happened that the tank leaked slightly and with the stove turned off it was easy to pull it off for welding. It will be replaced, but at the earliest after winter.

Kurtka na wacia wrote:

And as for the pump that you have installed, I somehow have no conviction. A friend installed one but quickly abandoned it in favor of a standard one with rigidly defined rotational speeds. The electronic one was behaving unpredictably. The result was just underheated radiators. Apparently there were different modes of operation, but somehow it worked unreliably.

These types of pumps are good, but not in such installations, it's a shame about the pump for this installation. By the way, I am puzzled by the fact that people can afford such an expense, i.e. the purchase of a separator pump with a desilter which they cannot even install properly and cannot afford to modernize the installation that is being asked for! In this case, it is the resuscitation of the deceased, it cannot be called otherwise.
And even if a man wanted to help, it would not be possible because he does not know how many surprises there are in this installation.
I greet everyone.