Taco SR504-4 switching relay - first relay makes noise or drops on certain zones

criocin

Hello,

I have 3 zones on a Taco SR504-4 switching relay. One is on Nest with the AC and the other 2 are on Sensi.
When I turned on the heat on the Nest the first relay ( the one not related to the zones) started to drop here and there (maybe when the pump started?). I disconnected the AC from the Nest and now it does not drop anymore but it sounds that is about too (makes noise).
When I turn zone 2 which is on Sensi the relay makes a lot of noise but it does not drop.
When I turn zone 3 which is on Sensi the relay makes no noise.

I can't figure this out. I think is a bad relay which I don't think it can be changed individually. I might have to replace the entire Taco switching box.

Looking for advice.
Thank you

Jamie Hall

May not be a bad relay. Very often it is simply not enough juice to power the relay. What is the power source for all of this equipment?

Joe Mattiello

Hi
My guess, it is not the control. An easy test is to disconnect the thermostats and place a simple jumper across TT terminals to see if it still makes noises, or act erratically.

Some of these power robbing thermostats require more voltage than the control has available. I would check with Taco tech support at 401-942-8000. They are better equipped to answer these questions when attempting to trouble shoot a problem.

I’m curious to know how you make out.

SteveSan

criocin, as Joe suggested I would disconnect the t-stat going to your SR control and jump the R-W on the control to see if the issue is still there. Do you t-stats require a com wire and do you have the com going to the SR control? Because of the draw of all three t-stats you may require an external transformer. The 15va transformer on the control may not be enough. Attached is a wiring diagram to add an external transformer to your SR504-4. You can always call into Technical Services during normal business hours Mon-Fri 8am-5pm EST 401-942-8000 and just ask for Technical Services

criocin

The zone who does not make the relay noise has the thermostat with his own C and power.

The zone who makes the most noise has the thermostat C from the Taco SR control and has also a Two way zone valve (who uses the transformer on the control) before the pump.

So I think an external power source for all the thermostats might be the answer:

https://www.amazon.com/gp/product/B07DJ7RHS5/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I will let you know. Thanks

SteveSan

What type of zone valve do you have? I have wiring diagrams for our heat motor ( 3 wires ) and zone sentry ( 4 wires ) when connecting to an SR control.