pid heat exchanger for temperature regulation

[JEANST]

hello i would like some tips about pid regulating on hot water circuit with heat exchanger. i explain the context.
i have a primary water circuit with temperature between 100 - 105°C
this circuit is passing through a heat exchanger. an analog 3-way valve enable to modulate the water flow.
at the secondary circuit the temperature of water must be controlled (eg 70°C)
a temperature sensor gives a feedback to the PID controller to control the 3-way valve at the primary circuit. the amount of water i must heat is quite high (3000 l)

What i have observed is the system have a high delay before responding. and i have some over and undershoots a little bit more that i would like.

I have set a quite slow regulation with low P and high I , no D a the moment but i Wonder if it would not be better. if some D is necessary should it be high or low value ?

the question i have is how can i integrate this delay of reaction due to the system ? to have optimized parameters, with enough reactivity

any experience would be greatly appreciated

thanks

 

[shooter]

follow ziegler and nichols rules.
or use autotune.

 

[Peter Nachtwey]

The heat exchange sample from the control guru site.
http://controlguru.com/process-gain-is-the-how-far-variable/
My auto tune program for the same example.
http://deltamotion.com/peter/Scilab/

 

[JEANST]

thanks for you help i will check