Halstead Aces High, hot water problem

[lotus25]

We have a boiler that works fine as far as the central heating goes but with the domestic hot water the temperature fluctuates whilst the tap is on. It gets really hot then goes cold then back to really hot.

Have had three people tell me different things.

1, need a full chemical clean and replace the heat exchanger

2, replace the heat exchanger only

3, clean the heat exchanger and fit a magnet or something

Can anyone help as I now confused

 

[dneill12345]

sounds like the plate heat exchanger is blocked.replace plate heat exchanger or have it cleaned out.this is a very common problem

 

[lotus25]

Is cleaning of the heat excahnger called a chemical clean, or is a chemical clean when the central heating section is de-sludged?