White Rodgers zone valves

Dan_L

Hi all,
I went on a service call where the homeowner replaced all 3 of his thermostats that weren’t compatible with the 3 wire zone valves. All 3 zones are staying open. I only had one Emerson 1f56n-444 t-stat on my van & wired it in to the basement zone to test it & none of the zone valves reacted. I didn’t think to disconnect the other t-stats.

I got lost after that & wasn’t sure what to do. I thought there was possibly a wiring problem. My office had me leave & their sending someone else out tomorrow. My co worker thinks once the other t-stats are replaced everything will work. If the other 2 t-stats are still connected can that cause the Emerson t-stat to not react? I still get confused with these zone valves sometimes & want to learn what I missed.

I appreciate any help

EBEBRATT-Ed

Depends on what zone valve you have. Drive open & Spring return? or drive open --drive close?

Dan_L

It’s drive open, drive close

EdTheHeaterMan

Old T87F thermostats had 3 wires needed to operate that zone valve. R was common, W was to open the valve. Y was to close the valve. That worked because when the mercury switch was in the call for heat position, the R and the W was closed and the R to Y was open. As soon as the call for heat was completed, the R to W would open and the R to Y would close. You needed the special sub-base for the T-87 to use it that way. The heating only sub-base that came with that thermostat would not work because it had only R and W. the Y was screwed into a blank terminal that went nowhere.

That was in the 1950's when life was food and thermostats were analogue.

If you want to connect that valve to a modern thermostat, you can use a SPDT relay. the thermostat closes the NO relay contacts on a call for heat, then when satisfied the NO contacts open and the NC contacts close to power the closing motor to operate.

hot_rod

Is there a relay box involved? That simplifies the Wiring of 3 wire and WR zone valves All zone valves really wire easiest through a relay box 

if power stealing stats were swapped in, it is best to have a “C” wire at the stat, which is available on some relay boxes on the terminal strip for the t-stats 

EdTheHeaterMan

Here is a fix you can use with a RIB relay that everyone seems to have on their service truck today.
The top uses the 3 wire thermostat as designed. The bottom uses the RIB Relay (or any SPDT relay with a 24V coil). This relay has the Common Normal Open and Normal Closed contact that is needed to power the valve closed.

The only real benefit I see that this zone valve has is that you can use the end switch to close a set of dry contacts like all the other zone valves Terminals 2 and 3 on the valve actuator. OR, you can use Terminals 1 and 3 to power some other relay or gas valve that requires 24 volts.

1 & 3 = 24 volts
2 & 3 = Dry contacts (end switch)

Other than the 24V option, why bother with that contraption?

Dan_L

Thanks for the replies guys & great explanation with the rib relay. I have a better understanding of it now.

I think the guy going back today is going to put on new 3 wire thermostats. I'm just not sure if that's going to work since the one I used for a test did nothing. It would be a lot easier if they were the 2 wire zone valves