Some advice please. My boiler (a recent Worcester Bosch system boiler) is more or less next to the hot water cylinder (about 3 feet of pipe). The system is an S plan, the CH is in 28mm to the first branch (upstairs/downstairs) then 22mm then 15 etc. The hot water is in 22mm to the cylinder, the 22mm return is tee'd into the CH 28mm return. The problem is, when the hot water demands then the return from the cylinder is too hot, causing the boiler to shut down, then start, then shut down and so on (cycling?). This causes the CH to not work effectively. Is there a simple solution? (someone suggested putting 15mm between the cylinder return and the common return to throttle it?) Cheers.