Zone valves 2 wire vs 4 wire

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Old 03-27-14, 04:09 AM
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Zone valves 2 wire vs 4 wire

I've installed a multi-zone hydronic heating system and I've noticed that some zone valves have 2 leads and some have 4 leads. I understand that the ones with 4 leads have a pair for the aqua-stat of my boiler.

1. Is there a way to use the 2-wire type to also tie to aquastat?
2. If I can't tie to aquastat, what is the disadvantage of only connecting to the thermostats for these zones fed off from 2-wire valves?
 
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Old 03-27-14, 07:30 AM
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Shawn, give us more details...

Tell us the make/model of the valves for starters.
 
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Old 03-29-14, 05:04 PM
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Thanks for the interest NJ Trooper.

I have loked a bit further, and realized my post is wrong. I should have referred to the endswitch, no the aquastat.

I have Honeywell zone valves.

V8043A has 2 leads for the thermostat only.

V8043E has 2 leads of the thermostat and 2 leads for the endswitch.

The problem I have is that I have installed some V8043A on my system now. I know I can signal from the thermostat to the zone valve to open, but I am not sure how I can send the call signal to the burner relays.

Thanks!

Shawn
 
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Old 03-29-14, 05:38 PM
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The problem I have is that I have installed some V8043A on my system now. I know I can signal from the thermostat to the zone valve to open, but I am not sure how I can send the call signal to the burner relays.
Well... you can't...

You need an ISOLATED switch to connect to the boiler to fire it up.

I believe that the BODY of the valve is the same between the A and the E valves, so you could purchase some E heads for the A valves.

OR, you could pick up a Taco ZVC panel and jumper the endswitch connections in the panel.
 
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Old 03-29-14, 05:41 PM
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V8043A has 2 leads for the thermostat only.
They are used for constant circulation and boiler firing off high limit. Like in an apartment where the t stat only opens the zone....
 
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Old 03-29-14, 05:54 PM
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I see. Thanks for the help.

I cannot just include the call to the boiler circuit in the t-stat to motor circuit, and signal all at once?

Or, could I install a relay in a box and use that to switch to call to the boiler?

I suppose as long as these couple zones could be left to just respond to the thermostat, and the boiler will kick on when other zones call for heat, to keep water temperature up in the boiler. Maybe an option. They might circulate cooler water some of the time...
 
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Old 03-29-14, 05:56 PM
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I cannot just include the call to the boiler circuit in the t-stat to motor circuit, and signal all at once?
No, you'll fry either or both the 24V transformer for the zone valves, or the transformer in the aquastat. You would be connecting two powered circuits together and those transformers will cook.

Or, could I install a relay in a box and use that to switch to call to the boiler?
That's what the Taco ZVC panel would do for you.
 
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Old 03-29-14, 06:06 PM
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This is good information.

So I can install a metal box adjacent the zone valve and put a relay in it and run the relay off the thermostat circuit to the zone valve? Then, I can run off the relay into the circuit that signals the boiler (TT) along with the other V8043E already connected. Therefore, the relay is only a switch to open and close the TT circuit and won't add voltage. Is that right?

Thanks so much!
 
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Old 03-29-14, 06:16 PM
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Yes, you could do that with a DOUBLE POLE relay that has a 24VAC coil.

Actually, you could use a SINGLE pole relay and wire the COIL of the relay in parallel with the MOTOR leads of the zone valve. When the thermostat calls, it will energize both the relay and the zone valve.

Problem with this is you might need a larger transformer to power the extra load.

How many zone valves total do you have?

How many VA is your 24V transformer?
 
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Old 03-29-14, 06:18 PM
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Old 03-29-14, 06:29 PM
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I have multiple transformers and zone valves.

Transformers output 24 Vac at 40 VA and I understand that 3 max valves per transformer is allowed.

So, we are saying that if I do 2 ZV per transformer then I can use single pole? If I stick with 3 ZV per TX then use double?

Thanks!
 
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Old 03-29-14, 06:47 PM
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It depends on what the added relays are going to draw. Probably not as much as a zone valve, I would think you could still do 3 valves per transformer.

Are you dismissing the ZVC panel for some reason? It really is the cleanest, easiest, and probably by the time you get done purchasing boxes and relays and all that other junk, the cheapest.
 
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Old 03-29-14, 06:54 PM
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I see single pole relays for 6$ for fan switching and I would only use them for 2 ZVs and I have the other parts around. So i would save by not spending the 100$ on the switch box. And I like the challenge of it I guess - learning.

I will probably trial the system without the relays to see if the rooms are still comfortable from the boiler water staying hot from other valves calling. You have been very helpful and I have a better understanding now for sure. Thank you for the help.
 
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Old 03-29-14, 07:19 PM
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I like the challenge of it I guess - learning.
No problem with that!

Let us know how it works out.
 
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