My apologies if "help" isn't what this area is for, but I'd be grateful if you have any ideas. We've had our (solid fuel, Parkray) central heating system power-flushed by a professional local plumbing firm, a new Grundfos pump fitted, and one separate gravity feed (heat sink) radiator cleaned out. Now we get a whooshing and sound of water "bubbling up" in the radiators when we first switch on the pump, and then a slight rattling in them as bits or bubbles are shooting round. Worse, air is getting into the radiators and I am having to bleed them every morning. I suspect that air is being sucked into the system by the pump. The new pump has no bypass for "Low" operation, as did the old one - only the 1-2-3 selector, and it seems too powerful. What do you think? I have told our plumber what's going on and he sounded a bit puzzled. I have asked him to wait till after Christmas before. - Dan in UK