I'm looking at ways to automate a pool heater and I've found that my heater does in fact have fireman's switch terminals for a dry contact on the control board. Great! Now, the question I have is this: if the fireman's switch is shorted from the factory, why doesn't the heater just operate 100% of the time? If I connect a dry contact and it turns on the heater when the contact closes... why the factory jumper?
Here's an excerpt from the heater manual:
>To connect a 2-Wire Control (such as Pentair’s IntelliTouch or EasyTouch) or a timer:
>* Remove the factory installed jumper from the Fireman’s Switch terminals.
>* Connect wires between the Fireman’s Switch terminals on the heater and the relay.
>Connect wires from the controller or timer to the Fireman’s Switch. Controller, timer or relay should be sized to handle 24VAC at 0.5 Amp (because it will be completing the 24VAC control board circuit on the heater as shown in Figure 22).
If I can get away with it, I'm planning to use a Z-wave thermostat right inside the enclosure with a remote sensor installed to read water temperature. I'll connect the
dry "heat" contact on the thermostat to a relay and then connect the NO contact to the FS terminals and see if that works... but I just don't understand the heater operation as it applies to the jumper.
Asked another way: If you can connect a dry NO contact to the FS terminals, and the heater turns on when the NO contact closes... then why isn't the heater on 100% of the time when the factory jumper is installed? Does the controller somehow "know" that there's a contact installed by virtue of the fact that it's occasionally open?
I can offer: