Hot water pressure issues

Zab

3-4 years in the house, this has happened once or twice before and was fixed by a plumber. If you leave the hot water taps all off for a while and then open one it will run with some pressure for a little bit then either slow to a trickle or go off completely. This happens with the pump turned on or off.

The system is as here except there's nothing attached to 9, everything goes through the pump.



I turned off a valve on 4 and crossed the mains and hot water at the kitchen sink. I wanted it to flow through the tank and out the expansion pipe in the attic, but that did not happen. However, the cold water would flow out of all the other hot water taps in the house if they were opened.

After releasing all pressure I opened where the pipe 10 entered the pump. When I reopened 4 it would flow out of this pipe, although it seemed pretty weak. I'm pretty sure weaker than the usual pressure when the pump is turned off.

I emptied and refilled the attic tank on somebody's suggestion (crossing at the kitchen tap while it was empty) even though it didn't make much sense to me, but to no avail (if anything the hot water is weaker now) . I *think* the person who suggested it wanted the water to run through the cylinder back into the tank in the attic.

Any thoughts? Is the failure to get anything out of the expansion pipe significant? I'm tempted to buy a hose that will let me disconnect 1 where it enters the attic tank and jam it straight into 4? (as in under water in the tank) Most likely I will just call a plumber, I just thought I'd check what people thought.

Zab

Plumber came. He opened the pipe at 4 and emptied it into a bucket for a little then reconnected.

I wasn't there to ask him, but I'm guessing there must be a rise in the line somewhere between the tank and the cylinder.