What I wondered is if that bypass valve opens and bypasses the heater then heater senses low pressure and shuts down.
But thinking that wouldn't cause your flow to drop in the pool. Also seems if something was blocking it your pressure would go up.
I think James has the next next step and check vacuum at the pump. That's a weird issue
But thinking that wouldn't cause your flow to drop in the pool. Also seems if something was blocking it your pressure would go up.
I think James has the next next step and check vacuum at the pump. That's a weird issue