Digital DHW Tank Thermostat ?

[firebladerrw]

I have a 'Terrier' stat fitted to my DHW tank, and noticed (like room stats) that its quite inaccurate when switching off/on for hot water. Its almost 10 degrees of a spread !

I've had a look and can find any digital stats for DHW tanks - has anyone come across one?

 

[Gasinayr]

Try Potterton PTT2 cylinder stat

 

[gas4you]

Only one I've seen and used is the Danfoss wireless cylinder stat.

 

[D_Hailsham]

I have a 'Terrier' stat fitted to my DHW tank, and noticed (like room stats) that its quite inaccurate when switching off/on for hot water. Its almost 10 degrees of a spread!

I think you will find that all tank stats have a wide differential; this is deliberate. The water is heated to 60, which is enough to kill off any legionella bacteria. When it is drawn off, it will need to be mixed with cold water to bring the temperature down to about 40C or less for baths etc. As the HW temperature drops, due to addition of cold to the cylinder, the amount of cold needed in the bath will reduce. When the cylinder water drops to 50C, the cylinder thermostat will close bringing the temperature back up to 60C.

This means that about a quarter of the cylinder is drawn off before the water is reheated.

Modern digital room stats have a spread of less than one degree.