Heating Help

Tekmar 508 & Taco SR504

Trying to help a buddy over the phone wire up a Tekmar 508 w/a slab sensor (looks like an older model) to his existing Taco SR504 Switching Relay, his Drawing is attatched, The slab sensor goes to #1 & #2, then he has to run wires  from 5 & 6 on the 508 to the t-stat connections on the Taco panel, and I think you will need to add a seperate 24v Tranformer and make your low voltage connections to  C&R on the 508 to power the Mircoprocessor is this correct? Is this what they mean when they say a Clean 24V Power Source? Thanks guys

24v

He may be able to pull 24v from the SR504 panel to save the cost of buying a transformer.
The Taco relay should have c - r terminals in the upper left hand corner, but the taco transformer is only 15va, enough for a thermostat.