How do install a timer for pump?

[KurtV]

Some (probably most, maybe all) newer heaters won't fire unless the water is flowing. Check your heater manual and if that's the case, you needn't worry about it; the heater will come on so long as the temperature is below where you have the thermostat set and the pump is running.

[Poolsean]

There are some considerations to think about. If you are prone to freezing temperatures, you will want to make sure your timer is capable of a "freeze protection device" that will activate the pump when water temperatures fall below a certain temperatures. I believe it is because of this that the pool dealers recommend running pumps 24/7, during your swim season. Otherwise there is a liability issue with pipes cracking.
With regards to the heater, the heater is equipped with a pressure switch that will shut the system down if there is insufficient flow. However, gas heaters tend to hold alot of heat after a pump shuts down. If the heat is not allowed to cool down, it can melt down your pipes and cause damage. Therefore there is a device that is called a Firemans switch that shuts down the heater circuit 15 minutes before the pool pump shuts down for the purpose of cooling down the heat exchanger.

So, to install a time clock is nothing more than a mechanical gear mechanism that activates a micro switch that either opens circuit (OFF) or closes circuit (ON) from the main power wires into the time clock to the pump wires.
It is not hard and any electrician can read the wiring schematics to wire it. If this will be mounted outdoor, find a time clock box with a weatherproof housing. Intermatic offers a metal box for indoor (no weather stripping), metal outdoor box (with weather stripping), or plastic outdoor boxes. It's your preference.
To make it simple, you have two power wires and a ground wire (green)coming in and is wired to a terminal strip (usually marked as LINE) and a ground lug. Then you have two wires and a ground that is connected to another two terminals on the terminal strip (usually marked a LOAD) and a ground wire (also green) that is attached to the same ground lug.

[imfignewton]

The Intermatic models to look at are T104R201 or T101P201. Make sure the electrician uses ligiud tight conduit and connectors for the timer box and all equipment.

[handy1]

In looking at available Intermatic timers, i see one called the PE153P which appears to be a new digital timer. Has anyone had experience with this timer?