Pump and Heater Piping

I just got a NG heater and going to be piping it in. I have had a solar heater for a couple of years so most of the pipe already exists. Now i now some of this needs to change for the NG heater. Plus I will be adding a inline chlorinator this year.

I do know that the chlorinator needs to go after the heater.

I guess my main question is should I install a check valve between the heater and chlorinator?

Should I instlall install the quick disconnects on each side of the chlorinator?

Is there anything else I should be aware of?

My setup has a check valve after the heater. You also want to use cpvc pipe. Standard pvc will melt if the pump turns off and the heater is on. The water in the pipe is very hot. Disconnects make it easy to work on or replace things without cuttiing pipes.