digital thermostat for immersion tank

Synkro

Hi

Im looking to get a digital readout of my hot water immersion tank

Q1. Are the strap on/contact thermostats that read the temp of the 'cylinder surface' as accurate in telling actual water temp as those that are immersed in the tank in contact with the water?

Q2. Would there be any point measuring the water temp at different cylinder depths, or does the heat rapidly diffuse throughout the tank?

This is the closest thing i could find to an immersion type thermostat

http://www.smarthome.com/70087/Sensaphone-FGD-0105-10K-Immersion-Temperature-Sensor/p.aspx

I'm assuming I could just insert this into the tank by removing one of the large hex nuts (looks like an aux hot water output) and screwing it in place?

The other alternative is something like this

http://www.draytoncontrols.co.uk/DigistatCRFCylinderThermostat.aspx

The end goal is to feed into a home automation system Im putting together, and also to try determine the most efficient hot water heating cycle/schedule

Thanks

Adrian

JohnnieK

A screw in prob stat would be more accurate by a couple of degrees than a strap on stat. You can put it into the port you suggested (when the cylinder is drained of course) but with any stat you will only pick up the temp at that point in the cylinder.