Thanks for the super-fast response. All the ProLogic controller does right now is let me automate turning on 'high speed' for a couple of hours a day, and then 'low speed' for a couple of hours a day... are you saying that it should work the exact same for the new SP3215X20XE? my installer says he spoke directly to Hayward who told him it won't work with ProLogic, and I'd have to pony up the $$$ for the VS900.
Your existing pump is a 2-speed, not a variable speed pump, so the ProLogic was set up in its configuration menu to control that by using two separate relays.
As JamesW points out, the ProLogic can turn the XE motor on and off with a single relay (#1 relay is always the pump relay). The internal programming in the motor will then take over. You set the speeds and duration in the pump itself, the ProLogic will have no control over those with that XE pump, but it will work with the Hayward, or any other brand of automation, by being turned on and off, much like a single-speed pump. It all depends on how much control you want over speeds, etc.
The owner's manual says that the ProLogic can control up to 6 different speeds on a Hayward VSP like the VS900. Takes a bit of programming. If your installer doesn't think the XE will work with your system, he likely won't know how to do that programming.
You will never need that kind of control if you have been happy with the 2-speed pump up to now. The XE gets installed (plumbed in), wired to the #1 relay, ProLogic is re-set to control a single-speed pump (preferably with the pump relay set to be "on" for at least 16 hours), the internal programming of the XE pump is chosen (there are various options to choose from), and you are good. Its not that hard to do
If you want the XE and your current installer is hesitant, either insist on it, or find a new guy. Your pool, your money, your choice.
