Dribbling hot water

[Twinkle]

Grateful if somebody could help.

I have a gravity fed DHW system (cold water tank/indirect vented cylinder) with a Worcester system boiler. No FE tank.

My trouble is with the hot water from all taps/showers-its at a trickle (about 1litre/min!!), the cold water outlets are all fed from the mains and are fine. The cylinder is about 10-13 years old. The pipework from the cylinder to the 1st upstairs outlet is about 12m long in 28mm, mostly running horizontally. The dramatic decrease in flow has happened quite suddenly over the past few weeks. The water although at a trickle does heat properly (some consolation!!). The problem goes away for about a week if we drain the whole system but comes back after about a week.

any suggestions?!

 

[croydoncorgi]

If the feed INTO the cylinder from the cold tank is OK, there's almost certainly an airlock in the flat-running pipe you describe, especially if all the Ts on it run downwards. If you have a mixer tap in the bath, turn both valves on full and put you hand over the spout to stop the flow for 30 seconds or so. The idea is to lmake the cold water push the air back towards the HW cylinder and out of the vent pipe. Might work. Draining the system is not likely to work because filling the system with fresh aerated water will just re-form the airlock.

 

[kevplumb]

have had a similar problem turned out to be the cylinder full of scale blocking the cold inlet