Immersion Tank - Noises at night

[Hermit]

My old immersion tank starts making tap-tapping noises at about 2am most nights, the sound travels through all the pipes around the flat. I've had some advice about keeping a tap dripping etc to reduce the pressure, but the noise still occurs. The only thing that stops it is turning off the tank's water supply.

I've been in the loft and the noise is coming from one of the 2 pipes that come out of the top of the tank and go out through the roof (was told they are overflow pipes?). Is there any cheap and easy way to have this fixed, or would it be more economical in the long term to replace it with a modern boiler?

I need to tell my landlord, and want to convince her of the best thing to do.
Any advice welcome, thanks.

 

[fuzzy]

how hot does it get?

 

[Hermit]

Hi Fuzzy,
It can get extremely hot if I have it on for too long, but I usually just use the boost function when I need it, so it's about the right temp.

I don't have it on to heat through the night on Economy 7 anymore, I just use the 'boost' when I need hot tap water - not every day as my appliances heat water for themselves.

It isn't switched on when it's making those tapping noises. Do you think the thermostat has anything to do with it?