This is our first cold snap with the new pool, and I'm concerned about its freeze protection.
I have two pumps: the main one, a Pentair variable-speed that claims to have freeze protection (at least, it's an option in its menu), and a separate one to run the sweeper robot thingy. The Pentair is set at 50F, the sweeper one at 38F.
This morning I woke up to 33F outside. When I looked out the window, the sweeper robot was moving around the pool, so that's clearly fine. But the main Pentair pump wasn't going.
This concerns me, but I have a theory as to why it *might* be correct. The thermostat for the sweeper robot pump is in a separate box with its timer control, so clearly it's being triggered by the air temperature, possibly with some influence from the concrete foundation it's attached to. So when the air temp goes down, this pump will go on, and that's all there is to it.
But the main pump's thermostat sensor (again, assuming that it's built-in, and not something I need to buy separately) is integrated into the device itself, and is presumably influenced by the temperature of the water it's pumping. So even if it did come on sometime during the night (I don't know), the water, which is well up into the 60s, would warm up the pump a bit, to the point where the sensor is above the 50F trigger, even if the ambient air is much colder, and so the pump could shut itself off again.
Is my theory correct, that things are probably operating fine even if I don't see the pump going when the air temperature is really cold, or should I be talking to my pool builder? Does anyone know about Pentair pumps, whether the thermostat sensor is built-in or if I need to purchase separately?