[ben's plumbing]

the smart valve1 has a 4 pin molex plug that's connects to top or side.this 4 pin plugs houses 4 wires.24 volt hot,24 volt common, electronic fan timer output, and a 24 volt input from pressure switch...you should have 24 v present between the 24 v hot and common at all times ..when power is applied to furnace...with a heat call the blower control will energize the induced draft blower which will close the pressure switch. When the normally open pressure switch closes, 24 v will be introduced to the pressure switch wire at the valve. This allows the furnace to attempt to light the pilot.After ignition has occurred the valve will send a 24v signal back out on the eft terminal to energize the blower motor...If the pilot will not light,verify voltage to the pressure switch terminal and the 24 v hot terminal. check for voltage to the ignitor with the ignitor plug still attached to the valve. If the pilot will light but not main burners, check flame sense to the valve.veritfy that the pilot tubing is securely attached to the valve...tech tip from bens plumbing..: