Pool Heater Banging Sound

[runboy]

My pool heater will make a loud banging sound on occasion indicating that the water inside is boiling.
My initial finding is that my low pressure switch is not working correctly since I used to get a LO indication and the heater would turn off if I turn the outside bypass valve creating a low flow situation. But wouldn’t the low pressure valve normally fail in a position so the pool heater can’t start?
My question is just, is that the only thing that’s wrong? Should there be other safety measures preventing a boiling scenario?
I’ve read that the internal bypass may be bad. How can I check this?
Heater is a Hayward H400

 

[mas985]

That may be due to calcification. It is the same thing that can happen in a water heater.

If you clean the heat exchanger, it might help. At the same time, you can check the bypass valve. But it requires disassembly of the heater.

 

[runboy]

That may be due to calcification. It is the same thing that can happen in a water heater.

If you clean the heat exchanger, it might help. At the same time, you can check the bypass valve. But it requires disassembly of the heater.

It was the internal
Bypass valve and it’s actually pretty easy to replace. Just unscrew the manifold where they external pipes connect and it can be taken out and replaced easily. Part is like $40-50 on Amazon.

 

[runboy]

It’s pretty flimsy plastic, so I would imagine it’s pretty normal for it to break.