Hot water cylinder temperature

[MattChan]

The stat on my open vent cylinder is set to about 45 degs but the water that comes out is at about 70 degs!

I thought the stat may be faulty so I put a thermo couple behind it and in contact with the tank and it reads <45 degs.

The cylinder is around 8 years old and its in a very hard water area.

Is this normal operation or has something gone wrong?

 

[kevplumb]

where is the stat

 

[Nixt]

In which case the lower cylinder is full of scale so preventing the stat from sensing. In any case water at top will be hotter than stat position.

 

[Softus]

Could easily be the MZV letting by.

 

[MattChan]

Stat is about 250mm up from the bottom...

I was wondering about scale... is it work throwing some chemicals through it?

Whats the MZV?

 

[MattChan]

Is the MZV == multi zone valve?

The rads don't get hot when its in HW only mode.

 

[Nixt]

I was wondering about scale... is it work throwing some chemicals through it?

Not a good idea unless you want to glow in the dark after your next bath.

 

[kevplumb]

Is the MZV == multi zone valve?

The rads don't get hot when its in HW only mode.

but it might not be closing when the cylinder is up to temp

 

[MattChan]

I was thinking fernox DS-3

http://www.fernox.com/?cccpage=ds3&sub=6

Or is that a bad idea that will make me glow in the dark?

 

[MattChan]

Is the MZV == multi zone valve?

The rads don't get hot when its in HW only mode.

but it might not be closing when the cylinder is up to temp

At this point I am just running HW only mode though so when the stat says the cylinder is at temp the pump stops. Its more a case of the stat not being able to get a reading of the actual water temp. Unless I've missed the point, which I probably have after 3 pints of abbot

 

[kevplumb]

Its more a case of the stat not being able to get a reading of the actual water temp.

cos the scale act's as an insulator

 

[Nixt]

I was thinking fernox DS-3

http://www.fernox.com/?cccpage=ds3&sub=6

Or is that a bad idea that will make me glow in the dark?

Chemicals are for flushing the central heating, not sanitary water.

 

[Softus]

Stat is about 250mm up from the bottom.

Too low, unless your cylinder is only 750mm tall.

 

[MattChan]

Anyone tried this DS-3 stuff? Is it any good?

What I don't get is that my neighbor doesn't have this issue and their cylinder is 25 years old

Is there anything that could be causing the premature scaling of my cylinder?

 

[Softus]

Is there anything that could be causing the premature scaling of my cylinder?

Boiler stat set too high. Cylinder stat positioned too low.