Check valve choice?

I will be reinstalling my pump and heater soon. This year I would like to put a check valve at the heater to prevent high chloride water from back washing into the heater when the pump goes off. I am using an offline Hayward chlorinater which injects after the heater.

What is the recommended style of check valve? Flap or spring? Or am I just over killing my thought and the valve is not necessary? Thanks.


TFP Expert
LifeTime Supporter
Jun 7, 2011
Midland TX
I'm not sure I understand your question. Are you talking about keeping water from an in line Chlorinator backing into the heater? In whatever case, I'd think a standard spring flap type would work. That's what mine is. If you really wanted to fancy it up, you could add a FloVis that would give you flow indication, and the same thing all at once.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
If you are going to install a check valve then one of these Jandy styles is the best because it can be easily service down the road.
Pool Check Valves. Swimming Pool Check Valves.

I don't think it is really necessary. The real question is are you really sure about using that trichlor puck chlorinator? Each puck adds a lot of CYA and it won't take long before there is too much CYA in your pool. More here, Pool School - How to Chlorinate Your Pool