Pool heater bypass and check valve

[DivingIn]

I'm installing a new pool heater for my inground pool. I am going to plumb in a bypass so I can bypass the heater when it's not in use. I know I need a check valve between the chlorinator and the heater outlet. I also read somewhere that there should be a check valve in the bypass system.

So, looking at the diagram, I'm wondering if I need one or two check valves. If only one, would it be in position #1 or #2? Check valve #1 only would stop the chlorine from backing up, but when the heater if bypassed, pressure would be seen by the heater outlet.

Check valve #2 only would stop chlorine from entering the heater outlet, and stop water from entering when the heater if bypassed. But chlorine could conceivably enter the filter when the heater is bypassed.

Thoughts?

Thanks for your help!

 

[ajw22]

You only need #2.

Chlorine entering the filter is not an issue. Tablets also contain acid. The acidic water entering a heater can corrode the heat exchanger. That is what valve #2 protects.

Note that we do not recommend using tablet chlorinators. They constantly add CYA and eventually your CYA level becomes unmanageable. We recommend chlorinating with liquid chlorine, a SWG, or Stenner pump. See

How to Chlorinate Your Pool

Before chlorinating your pool, you should know these simple tips. Learn the best way to add chlorine to your pool.

www.troublefreepool.com

 

[DivingIn]

Thanks for your reply. I'm a big fan of the TFP method, and I use liquid chlorine. I only use the chlorinator when I'm away from home for a week or more. My CYA is still very low (10).