I moved into my house last year. Snow fell and the two main radiators in the lounge and kitchen/diner just reach heat best described as warm. They have been bled. I had the boiler replaced and this works beautifully. All the remaining radiators heat up quickly and are very hot but not the two in question. I have now had three engineers in and the general opinion is that I have small bore pipes which is a problem. A power flush has not been recommended as it may dislodge a blockage and make matters worse. Could try some sort of inhibitor but this also may make matters worse. The only other solution is to dig up my floors (solid) to try and find a blockage but this may create chaos and still be difficult to solve. Balancing the radiators has been attempted without any resolution. The engineers just leave shaking their heads. I am therefore at a loss as to what I can do as the rooms are so cold despite the temperature being as high as it can go.