Hot water is too hot whenever CH is on

[mudassiraslam]

Hi - need help related to my old potterton regular boiler system. As I understand there is Potterton gas boiler which turns on based on the timer or whenever I want to manually turn on the water or CH. Also there is a water cylinder with immersion heater as a back up and its electric switch is constantly been turned off as I was told it is only needed in cases the gas boiler does not work.

Now the problem is that when HW is turned on, gas boiler starts and no issues with the temprature of the water. However as soon as CH is turned on, there comes a sound from the boiler as if the electricty is passing and gas boiler only turns on after few minutes however that electricity sound keeps coming throughout the CH session and even after the CH is stopped. This things causes the HW to be extremely hot and I cannot see tempratures coming down even after the CH timer switches off.

My guess is that is something to do with the electric immersion heater turning itself on (although its main electricty switch is off) and does not turn off keeping the water extremely hot.

Any ideas and thoughts? - thanks

 

[Agile]

It will not be the immersion heater.

But some possible fault with your system.

I suggest you call an engineer to service the boiler and look at the operation.

Tony

 

[JohnD]

It is more likely the (electrically operated) motorised 3-port valve which is intended to direct the heat from the boiler to either the cylinder or the radiators. This does wear out after 20 years or so.

Search "port valve" in the plumbing section. It is very common query. Unless you are fond of diy plumbing you will need a mender.

In your particular case, it is not a gas part so the person changing it can be a plumber, it does not need a boiler engineer.

In some more modern boilers, it is a part inside the boiler so is more expensive and difficult to change.

Edit
If the boiler has not been serviced recently, I don't disagree with Agile.

To avoid the risk of scalding before it is repaired, you can probably turn down the temperature knob on the boiler.