We have just had a new oil boiler installed and now we can only have hot radiators upstairs OR downstairs. If I restrict the flow on all the rads upstairs the downstairs ones heat up. If upstairs are open anything more than a couple of turns, the downstairs rads stay cold. I have bled all the radiators while hot and cold and now no air comes out. Everything worked before we changed the boiler. Is it coincidence? Or has the heating engineer done something wrong? Could the pump no longer be powerful enough.
You need to rebalance the system mate, presumably the new pump is a different spec (not necessarily wrong)
do a youtube search - hundreds of videos which will explain how to do it. Essentially just adjusting the valves on all radiators so you get even heat distribution.
Thank you. I have done that and it worked for a few days. Maybe the engineer changed them when he commissioned the boiler. I’ll do it again.
Discovered the problem - the boiler had lost pressure. For some reason I have to re pressure the boiler 2x week. I can’t see any leaks anywhere, but I guess there must be?