How a Silvia Works|
On, heating up
On, at temp
Steam, heating up
Steam, at temp
Pumping hot water
Modification for PID
Dual Setpoint PID
Advanced Dual Setpoint PID
Advanced Dual Setpoint PID Wiring Schematic|
In this example we have further modified the second setpoint wiring. All changes in this modification are made in order to get the illuminating lamp in the steam switch to function when the switch is used to select the second setpoint. All the variations from the previous page are to achieve that function.
The original lead (in red) at the back of the steam switch remains connected as well as the black lead on the other end. I have added a jumper from the black lead and it goes to the windings of a relay (6). The green lead from the steam switch also goes to the relay's windings.The black lead at number "7" uses the terminal on the steam switch that was vacant up until now. Normally, that side of the switch just turned on the internal indicator lamp, but it now also controls the other wire that powers the relay so that both the neutral and hot sides are switched for added safety.
When you turn the steam switch on now it will control two things- it illuminates the lamp in the switch and it energizes the electromagnetic windings in the relay.
At the other end of the relay we see the same two wire that went from the PID's second setpoint selection terminals to the steam switch. These same two wires now connect to a pair of normally open ("N.O.") switch contacts on the relay.
When the relay is energized, the electromagnet is energized, the contacts we are using in the relay are closed, and the second setpoint is selected.
Be aware that the relay MUST have windings rated at 120 volts AC or it will either not operate or burn out. The ratings of the contacts, given separately n the specifications for relays, must match the PID's requirements fro such function, but since most PIDs send nominal current for this function, all you need to worry about is the rating for the windings I first mentioned.