Why is no water coming out of my hot taps?

[dottygamekeeper]

We went away on holiday, before we left the waterflow from hot taps in kitchen/bathroom (shower, bath and basin) seemed normal. On return, nothing is coming out of the tap. Cold water is fine.

We have had two plumbers out, they have checked the cold feed into the hot water tank (direct feed on mains pressure), which is fine, the tank is hot, they have rodded through the hot water pipe which comes out of the tank as far as possible. This has meant that some water comes out initially, but dries up after a few seconds of running.

Their solution is to drain down the tank and replace it - they are saying it must have scaled up inside? This is a boiler and tank which was new 4 years ago, in London (so hard water area) but none of the neighbours in the block (which was new build, so all had same boiler systems installed,) are having the same issues.

One suggested powerflushing the system - but I thought that was what you do to the radiators, not the hot water tank.

Any suggestions? PigletJohn are you around?

[dottygamekeeper]

Bumping in the hope that PigletJohn might have some logical suggestions!

[PigletJohn]

What make is your white cylinder?

An unvented cylinder has multiple safety controls built in and should only be serviced by someone who has the G3 qualification. Some heating engineers have it. Did your plumbers?

[dottygamekeeper]

Thanks PigletJohn - first plumber admitted he hadn't seen one of these before (it is a Daikin heat source system), so I told him not to touch the cylinder itself and that I would get a second opinion. All he did was check the incoming cold water supply.

Second engineer was sent by Daikin but said he had never come across this issue before - Daikin have now agreed to send someone else out, at no charge to investigate further, and I assume they will have the relevant qualification, thank you for clarifying this.

[PigletJohn]

Sounds like the right route.

The maker's engineer should have enough experience on this model to diagnose the cause of the problem. I wouldn't be surprised if it is something to do with a pressure control device.