[wolfrpi]

Lawrence - you are indeed correct. I believe the situation is analagous to the formula V=IR. If R is resitance and the thermostat orifice provides this then there will be a voltage drop (pressure?) over the thermostat. In this case though I believe the current (flow rate?) to be pretty small along with the resistance. I think this is due to the speed the waterpump spins at and the restristion that the orifices in the head provide. With the 160 thermostat, at higher speeds in my 951, the temp needle falls below 1/4 if you can believe it!

Erick