Pool Timers and Panels

What is a T104, and why does everyone seem to have one?

It is the Intermatic 24 hour mechanical time switch in its most common form, and it has been the default pool timer for so long that the whole T100 family is what parts are sold against. Our parts here name T100, T104, T106, T170 and T180 series. The reason it survived is that it does one thing with a motor, a dial and a switch, all of which can be bought separately, so a forty year old timer is usually repairable rather than scrap.

How do the little tabs on the dial work?

They are trippers, and they are the whole programme. Two clamp onto the rim of the dial, one marked on and one marked off, and as the dial turns each one physically pushes the switch as it passes. So setting the schedule means loosening a screw and sliding a tripper to the hour you want. If the pump runs at the wrong times, the usual cause is not a fault: the dial has drifted because the power was off, and it needs turning back to the real time of day.

Does the timer have to match the pump?

Yes, and on horsepower rather than just on amps. A time switch carries both ratings, and ours publish things like 30A at 3 HP on 120 or 240 volts. The horsepower figure exists because a motor draws a large surge as it starts, far above its running current, and the switch contacts have to take that surge thousands of times. A timer rated only on amps can look adequate and still burn its contacts. Match the pump's horsepower and voltage and the amps look after themselves.

What does a freeze protection thermostat do?

It overrides the timer and runs the pump when the air gets cold enough to be dangerous, because moving water is much harder to freeze than still water, and a frozen pipe or a frozen pump is an expensive morning. It wires alongside the time switch and simply closes the circuit below its set temperature regardless of where the dial has got to. In a climate that only dips below freezing occasionally it is the cheapest insurance on the pad.