Taco SR502-4

JMC_Services

Hi
  I’m installing a Rianni combi boiler with a Taco SR 502.  It has a 2 zone switching relay.
  Everything seems to be wired correctly, the thermostat calls for heat and the boiler fires.
  The problem is that the zone led’s are not coming on and neither are the pumps.
  I removed all the thermostat wiring and jumped across RW and still no change.
  I have currently tied the pumps together with the power to keep the pumps flowing.
  Any help would be appreciated.
  Thank you 

SteveSan

If you are in front of the control please give Taco Technical Services a call during normal business hours Mon-Fri 8am-5pm EST 401-942-8000 and just ask for Technical Services. Are you getting voltage out of the transformers and are the fuses good? Be sure that the factory jumper between ZC/ZR is tight.

JMC_Services

Fuses are good.  No voltage out of relays.  Voltage out of the transformer.  ZC/ZR are tight

pecmsg

Did you measure voltage across the fuse?

Why are all the Hots wired together?

Alan (California Radiant) Forbes

Why are all the Hots wired together?

"I have currently tied the pumps together with the power to keep the pumps flowing."

JMC_Services

pecmsg said:

Did you measure voltage across the fuse? Why are all the Hots wired together?

pecmsg said:

Did you measure voltage across the fuse? Why are all the Hots wired together?

pecmsg said:

Did you measure voltage across the fuse? Why are all the Hots wired together?

Did you measure voltage across the fuse?

  I have 120volts on both sides of the fuse, but when the thermostat calls for heat and the relay clicks I loose power to the relay 

Joe Mattiello

Place a jumper across R/W for a validated demand, see if you have voltage at ZR terminal
let me know 

JMC_Services

Yes, voltage at ZR.
  I spoke with Taco tech he thinks it might be stuck relays (bad)