Glow-worm xtrafast 96 - low pressure from hot water

[Fallen Idle]

Problem: Turn on hot tap and initial burst of water which immediately slows to a trickle.
Temp. is OK, cold water pressure fine. Have cleaned inlet filter, no difference.
Problem occured shortly after new water main installed as a replacement for original lead and steel pipe.
Any ideas? Help much appreciated.

 

[Dan Robinson]

Any old stop cocks lying around?

Tap mechanisms OK (does this happen everywhere?)

 

[Fallen Idle]

Thanks for your interest
I replaced the stop cock for a new one when I did the water main.
All the hot taps are now very slow.
Cold water pressure seems fine.
I assume that there is no hot water pump in this boiler and that it relies on mains pressure. I suspect a blockage of some kind but don't know where to start.

 

[ChrisR]

Sounds like a blockage.
Either in pipes, or boiler.
Other taps??

If suspect in the boiler, remove the flow sensor, filter and flow restrictor. Inspect flow restrictor, consider leaving the darned thing out. The O rings on them can swell up.
If ok, connect something like a flexible tap connector at the red arrow

to see what the flow's like.
If ok, blockage is more likely to be in the heat exchanger than the outlet pipework - it has narrow waterways. So I'd take it out and clean/inspect it.

 

[Fallen Idle]

Souns like a job for the afternoon, thanks very much for the advice, I'll let you know how I get on

 

[Fallen Idle]

Problem solved.
That was a good tip about fitting a pipe to test pressure coming in.
The problem was the isolating valve on the cold water inlet fitting. It had only ever been turned 1/4 on since installation because it was sticky and because the manual suggests that it only needs a 1/4 turn (although this instruction refers to the other isolating valve).
Dismantling and cleaning and then turning it fully on sorted the problem. Deep joy, the system now works better than it ever has with zero expenditure.
Thanks for your help, all hail the internet!!

 

[Dan Robinson]

Great News!