Problems with air entering central heating system

Air entering central heating system and hot water pumping over into make up tank in artic when h/c control is switched on. There is no problem when only c/h is on! this situation as only occurred since replacing my Grundfos UPS2 with a UPS3
I have tried the pump on different speeds . On the box that the pump came in it stated " Model A" Is there more than 1 UPS 3 models?

Any advice would be greatly appreciated.

Regards.
James

Can you give the exact details from the label on the UPS3, also any idea of what mode/settings you have tried, also a few photos.
Also any idea of what mode/setting the UPS2 was on, did this pump also have LEDs and a setting button.?

If the below is your pump, suggest (if not already tried) CP1, bottom right or PP2, second down on right, hold the setting button for 3 secs until LEDs start flashing, then single presses to get CP1 (3M) constant pressure, or PP2 (3.8M) proportional pressure as indicated by the flashing LEDs sequence.