What would cause my hot water to splutter?

Cold water runs fine with good pressure, a mixer tap about halfway hot/cold runs fine and smoothly, but hot water only splutters uncontrollably, meaning you get burny burny hot water all over everything if you stand too close. Additionally, our shower pressure is a bit rubbish and I wonder if this is making it worse.

Ideas?!

Cheers! B

Is it just from one tap ?
Where is it ?
What sort of hot water system?
Any work done recently ?

From all hot water taps
Flat is all on one level, hot water tank is next to bathroom, kitchen tap is 10 yards away
Hot water tank has 2 immersion elements, one of which is almost never used (connected to a booster switch)
No work done recently
Shower pressure has gotten worse recently, feels like spluttering has too but not sure

Is it a vented or unvented cylinder ?

Tank stat knackered ? Causing the element to stay on all the time & boil up causing air – stuttering ? Either way, check the tank temp & I’d leave it off till fixed. Hot water tanks can go pop…

Unvented

I’m not aware of the tank ever becoming too hot, at least, touching the outside of the inch-thick foam insulation never feels any more than pleasantly warm?

Is the water any hotter than normal though ?

If you haven’t already, it would be worth draining and re filling the cylinder as this need to be done from time to time to re establish the air gap.

Found this to save me typing it all out 🙂

……

Turn off CW supply.
Open lowest hot tap
Hold open the red (usually) topped (Pressure and temperature relief)valve on the side of the tank by turning it – you may get it to stay open, or you hold on for an eternity until the hot tap stops flowing. Could be 15 mins or so
(Let) close the red topped valve.
Shut hot tap.
Open mains supply.
Wait till filling noise stops.
Open that same hot tap – it will sputter a lot as the air comes out.

Update: it worked. Drained the cylinder only partially, got a good slug of rusty water out and taps now running splutter free. Thank you!

Shower pressure still poor though. Bummer.