Vaillant EcoTEC 836 Whining Noise

[gdsmith]

I have a Vaillant EcoTEC 836, which was installed in 2010. In 2013, we had some work done to our house, which involved moving the water feed to the boiler and replacing part of it in plastic. The flow and return was also re-routed, leaving a 'dead leg' in situ. Since 2013, the boiler seems to have developed a whining noise when the hot water is run and it has been getting progressively worse. There is no noise when the heating is on. We have a good flow rate everywhere in the house and there is no noise when the cold water is run anywhere. The only other thing that I can think of is that the gas inlet valve has been limited because Vaillant said that the flow rate from the meter was on the lower end of the allowed scale (17).

We have had our boiler serviced twice since then and both times, the plumber said that it was just water velocity in the pipes. We also had Vaillant out to replace our diverter at the start of the year and they didn't say anything was wrong.

Does this sound familiar to anyone? Thanks.

 

[bernardgreen]

If there is any air trapped in the dead leg then water flowing past the end of the dead leg could be creating vibrations in the column of water in the dead leg. The same as a flute is made to sound by blowing across a hole at the end of a tube and not into the hole.