No hot water. 3 ladies in the house. I'm feeling the heat (but not from the water)

[Mike Jones Amber Hill]

Here's the problem:

• Central heating (wet underfloor) is fine.
• Hot water comes out of any tap/shower for 60 seconds, then cold.
• This happened suddenly, was working fine before that.
• Boiler working OK.
• Pipes within a couple of metres of unvented cylinder are hot.
• Pressure gauge to cylinder is broken (so can't read input pressure)
• Supplied by water main, good pressure in house generally.

My Theory:

• Water is hot in the cylinder and therefore heats up water in the pipes gradually.
• Whet tap turned, hot water in pipe comes through. This quickly runs off and only cold water follows.
• So, the hot water in the tank is not being pushed through the pipes, it just stays in the tank.

Is that a good theory? And if so, what would cause this? Tried turning of mains input to cylinder, opened hot tsp til it stopped, twisted the tun dish for a bit, refilled and the closed the hot tap. Didn't fix it. I am thinking do I need to drain the cylinder completely via the drain valve at the bottom, then refill? Also, could it be the silver automatic valve causing the problem? I actually have two cylinders side by side so hard to see how both ports would fail at the same time?

Any help? The ladies will be home soon 🙁

 

[ShaunCorbs]

Can't say due to it being a pain if the pipes are boxed in etc

You could do most of the donkey work eg finding the pipes making access etc

 

[Mike Jones Amber Hill]

Thanks for your advice, time to get someone in,

 

[Ben-gee]

If one of the bath mixers is playing up, I’d start there first.
Amazing how a thousand pound fancy tap can be brought to its knees by a 10p plastic nrv.