Hot water element replaced but now running hot and cold

[Truro Ex Pat]

Hi guys I have just changed the element in the hot water tank and now I get hot water which goes really hot then cools and then goes really hot again? Any ideas as cant see any airlock in the system?

 

[superheat6k]

There is likely a maximum temperature controller which mixes in cold to maintain a continuous temperature. Could be this is hunting. Try setting the thermostat on the immersion a little cooler, this might eliminate the hunting.

 

[Truro Ex Pat]

Tried turning it down and made no difference, I going to have the pump checked but wondered if anyone has come across this before?

 

[PCUK]

Can't be the pump. As already said, it must be the thermostatic mixer. Find that and start from there,

 

[aquatom]

It will do this if there is any air trapped in the top of the cylinder.

 

[Truro Ex Pat]

air could be trapped and this is a possibility as we have changed the element, how would you bleed it as I cant see anything on the tank to bleed it?

I have also found the thermostatic blending valve and wonder if this is adjustable or not?