System: Baxi 100HE (control knob set about 2/3 of max), 9 rads with Drayton TRV4 valves, plus 1 rad (in airing cupboard) on bypass loop with lockshield valves. Grunfoss pump set to position 2. Range Tribune sealed HW system. Whole lot is brand new (except boiler, which is 18 months old). Everything works fine and heats up amazingly fast, except....
Impossible to achieve more than 6deg temperature differential between flow and return (often less, when all the rad valves are open, and boiler is going full bore), and I've read somewhere (on this forum, I thought, but I can't find posting) that for condensing boilers to work at max efficiency, the temp diff should be 10-12deg or more.
Flow and return temps are approx 51deg and 45deg respectively, both measured simultaneously with pipe-mounted bi-metallic dial thermometers.
I've tried closing the bypass rad valves right down (to reduce flow through this rad and force water around the system and hopefully cool it down a bit) but makes little difference.
Should I worry about this, or just leave it? Or is there a magic solution?
Impossible to achieve more than 6deg temperature differential between flow and return (often less, when all the rad valves are open, and boiler is going full bore), and I've read somewhere (on this forum, I thought, but I can't find posting) that for condensing boilers to work at max efficiency, the temp diff should be 10-12deg or more.
Flow and return temps are approx 51deg and 45deg respectively, both measured simultaneously with pipe-mounted bi-metallic dial thermometers.
I've tried closing the bypass rad valves right down (to reduce flow through this rad and force water around the system and hopefully cool it down a bit) but makes little difference.
Should I worry about this, or just leave it? Or is there a magic solution?