Sime super 90 making high pitched humming, whining noise

[Zehroni]

Sime super 90 making high pitched humming, whining noise when there is a demand for DHW. as soon we open the hot water tap the noise get louder and louder. it does not do that when the CH on. the pressure is 1 bar.

 

[Agile]

Does it make the noise if the electricity supply to boiler is turned off?

 

[Zehroni]

no it does not. it only make the noise when there is a demand for DHW

 

[Agile]

Let me ask the same question another way!

If you turn off the power to the boiler, then create a demand for hot water by turning on a hot tap, does the boiler make that noise?

Tony

 

[Zehroni]

no it does not. it only make the normal noise of water running in a pipe. but the noise I talking about start as low then increases fast as the modulator works due to DHW demand

 

[Agile]

That is not clear.

When is it loudest?

 

[Zehroni]

Here is what happens in sequence

1. open that tap

2. hearing constant noise from water running through the pipe. This noise stays at the same level whether the boiler is switched on or off.

3. When the boiler is switched on. the below happens in sequence:-

a. The fan starts

b. Pump starts

c. Ignition starts

d. The boiler fires up; at this stage the noise start but low

e. Modulator kicks off the noise gets louder and louder within few seconds and stays loud as long as there is a diamond for DHW

4. Trun off the tap, the noise stops

 

[Agile]

You probably need a gas registered engineer to check the gas settings on your boiler.

The pump would normally start before the fan.

Tony

 

[ianmcd]

post a video of it happening and we might be better equipped to advise you