Erie 2 wire thermostat no power after installing new Taco Zone valve Controller

tctran_jm3

Hello and thanks in advance for any feedback.

I was running 2 Erie VL500 Zone valve controllers and ran into issues with the boards last week.
I went out and purchased 2 new Taco 6 zone valve controllers.

I have 8 zones in total with 8 thermostats. I have three (3) two wire thermostats, made by Erie and five (5) thermostats that are your standard heating / cooling thermostats. After installing the 2 new Taco zone valve controls, the 5 standard heating / cooling thermostats are working properly, but the three (3) two wire thermostats do not have any power. The two wire thermostats were working prior to installing the new zone valve controllers.

I took the cover off of the two wire thermostat and manually connected the red and white wires and the zone worked properly, opened the valve and turned on the boiler and circulator.




I don't know why the 2 wire thermostats appear to not be getting any power. The taco zone valve controller came with resistors for power stealing thermostats. I'm not sure if this is what is happening and if I should install the resistors.

thanks
Tom.

HVACNUT

Is R and W reversed?
Do the Erie thermostats take batteries?

SteveSan

Some two wire t-stats will still require the resistors between the W-C terminals on the Taco control. For some reason the Honeywell T87 need them. We will received a call that they are not working, they install the resistor and it is fine. Please give us a call Mon-Fri 8am-5pm EST if you need any assistance 401-942-8000.

tctran_jm3

SteveSan said:

Some two wire t-stats will still require the resistors between the W-C terminals on the Taco control. For some reason the Honeywell T87 need them. We will received a call that they are not working, they install the resistor and it is fine. Please give us a call Mon-Fri 8am-5pm EST if you need any assistance 401-942-8000.

Thank you. Are there any negative side effects from placing the resistor for w - c terminals for the thermostats that aren’t being powered?

SteveSan

@tctran_jm3 I checked with the Product Engineer and he states no issue with adding the resistor if not required to.

hot_rod

There is a "watch battery" Energizer 357, under the Erie logo in a little slide tray. It doesn't get charged by the wiring, needs to be replaced occasionally.

It was a great little thermostat. The manual explains when the resistor is needed.