Drop in hot water flow

[garryl]

I recently fixed a leaky tap in my bathroom, having first turned off the supply and drained the water tank in the attic. Ever since having done this, the hot water flow to all taps has dropped dramatically (it now takes about 20-25 mins to run a bath). The cold water flow seems unaffected.

The first few times I ran the bath after reconnecting the water, I also noticed a small amount of very fine black flaky deposit coming from the hot tap, so I assume that some mass of sludge has been moved within the system and is now causing the reduced hot water flow.

Is there anything I can do to try and clear this myself, or am I going to have to call in a plumber? The system is a conventional open-vented stored water system with a gas boiler and indirect cylinder.

Incidentally, I've tried forcing cold water from the mains supply into the hot water pipes in case I'd created an airlock somewhere, but that made no difference to the flow at all.

 

[ChrisR]

forcing cold water from the mains supply into the hot water pipes

Keep trying that.

 

[kevplumb]

sometimes helps to run the upstairs taps at the same time

 

[garryl]

Okay, thanks - I'll keep trying that. I've done it a couple of times so far - once with the taps closed until water came out of the tank overflow, and once open.

Do you think there's any chance of a "sludge" buildup somewhere, or is an airlock the only plausible culprit?