Stupid pump question

this may be a stupid question but im going to ask any way. im about finished with my single tier. here is the scenario

hose from bottom of HLT to pump input, pump output to top of MT (strike water or sparge). the pump primes fine and moves the water. when the water is gone in the HLT or when you have enough strike water and shut off the valve there is still a column of water between the pump output and the MT. is this normal?

my real concern is that i want to setup a heat exchanger in the HLT to do step mashing and that's a lot of wort trapped in the exchange coil and tube.

Yeah, that is normal. The pump cannot pump if the HLT runs dry (loses prime) and it certainly cannot pump of there is a closed valve on the inlet or outlet.

You wont trap wort in the coil, just pump your sparge water through the coil, that will push all the wort out.

thanks. just wanted to make sure i had not done something wrong. good idea about pumping the sparge water thru the heat exchanger. i didnt think about that.