wiring low voltage zone valves


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Old 03-24-09, 03:18 PM
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wiring low voltage zone valves

i have a boiler with a how water baseboard loop for the house. i installed 2 more zones using the taco 24v 3 wire zone valve. one for the basement & one for the garage.now i need a schematic to wire it all up to work properly. theres a honeywell L8124a aquastat that the original stat was wired into. i know have a seperate stat for all 3 but 2 zone valves is this possible? thank you for any help with this.
 
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Old 03-25-09, 08:15 AM
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If I understand correctly, I believe that you need to add a third zone valve. If you don't, then the original zone will get heat when either of the other two call...

Also, with the 8124A you will need to add a 40VA 24VAC transformer to power the zone valves.

What model # zone valves?
 

Last edited by NJT; 03-25-09 at 08:35 AM.
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Old 03-25-09, 09:07 AM
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thanx

thank you nj trooper. that's what I needed to know. I have to add another zone valve. I have the transformer. but I can wire these stats up without using a new relay board? the stats won't backfeed each other right?
 
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Old 03-25-09, 09:23 AM
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I think this is what you need to do:



No, no problem with 'backfeeding'... this is basically the same thing as in the Taco install sheet for the valves, I just moved some stuff around a bit to make it a bit clearer.
 
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Old 03-25-09, 04:51 PM
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It took me a while

It took me a while to see how simple this is/was when I did it some years ago.
It's just a couple of separate loops of low voltage power.
A loop[s] goes upstairs to your thermostat[s]. The Tstat is just a switch that goes on when the room gets cold. When it switches up in the room the circuit is complete and your zone valve at the other end gets power and motors open. That loop has done its work. When the room heats up the opposite occurs. It may just be a spring or other device that shuts the valve.

Now, the second loop of power is its own loop. It is no more related to the first than your bedroom light is to your bathroom light. It loops from the bottom of the zone valve to the aquastat's boiler triggering devices. This loop may draw its electricity from the same transformer, or it may get it from one inside the aquastat's box. When one of the zone valves has cheerfully opened up to receive water flow, the zone valve also mechanically flips an internal switch, the "end switch", which completes this second independent loop and powers the aquastat to make its relays fire up the boiler. As any one or all of the zone valves' end switches can be on, they share a common wire to the aquastat.

In our case we added a transformer for some new zones, and left the boiler's existing thermostat do the old zones. It had enough juice for some.
Hope I said this right. Joe...homeowner.
 
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Old 03-25-09, 05:30 PM
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If those are the TACO zone valves that use heat motors, they will each draw about 1 amp apiece. Or, 24 VA per valve. Three valves would equal 72va. Use a transformer that can handle the load.

Pete
 
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Old 03-25-09, 05:54 PM
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Actually you can do 3 Taco 555 power heads on a 40VA transformer. According to Taco it will work fine. This has always been there recommendation. The reason being that there voltage to the heat motors once open is intermittent to keep them open and not all the valves are driving open the same time.
See troopers diagram from Taco.
 
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Old 03-26-09, 03:47 PM
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That's interesting to know.

Pete
 
 

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