Adding a supplementary transformer for Taco zone valves

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  #1  
Old 12-30-16, 04:10 PM
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Adding a supplementary transformer for Taco zone valves

Hello all.

I'm trying to help a plumber friend with his boiler. He had no heat last night and he determined that his Honeywell Aquastat was no good. He attempted to replace it himself but struggled with the wiring and called me.

I'm not in front of the boiler currently so if I don't have all the details I apologize.

Here's what I do know:

- Gas boiler
- New Honeywell L8148J1009 Aquastat Relay
- 2 zones (Taco Zone Valves)
- No separate transformer for the Taco Zone valves

When I got there, I Googled the schematics for zone valves and aquastat and got it running for him. We tried both 2nd FL and 1st FL thermostats and both of the zone valves worked as they should and the boiler shut off when it should.

When I was Googling for the diagrams, I stumbled upon this thread here on the forums and noticed a member saying that he doesn't recommend powering 2 Taco Zone Valves off of the aquastat's transformer.

My concern lies with installing the 40va transformer and tying the zone valves into the aquastat. If I'm not mistaken, terminal: TV already contains power from the aquastat's transformer and I would also be tying power in from the supplementary transformer. Wouldn't/could that cause an issue with them "clashing"?

Terminal Z and W have a jumper in them and I have one side of the thermostats going to the Z terminal.

I appreciate anyones feedback on this!!

Below is a picture of the schematic
 
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  #2  
Old 12-30-16, 06:29 PM
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The dashed lines for zone three show you how to use an external transformer. You can power all the zone valves that way...just wire them all as shown by the dashed lines. (just the dashed lines by zone 3...not the ones by the gas valves)

If you wire it that way, there won't be problem with internal transformer. The internal transformer will power the end switches to determine when the boiler should fire, but the external thermostat will supply all the current for the thermostats and zone valves.
 
  #3  
Old 12-30-16, 07:40 PM
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Thanks for the reply CT.

On his system, the zone valves are different than what is pictured above; I believe those are Honeywell zone vales. The valves he has are those standard Taco valves with only 3 screws like this:

[ATTACH=CONFIG]75068[/ATTACH]

Could you explain how that would work in my scenario? Also is there a standard meaning for what TV W T and Z stand for?

Again, I appreciate the help!
 
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  #4  
Old 12-31-16, 09:14 AM
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You wire it just as shown in your last post. There still won't be a conflict between the transformers because only one side of the two transformers are connected together at terminal 2.
 
  #5  
Old 12-31-16, 11:17 AM
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Carbide, I am going to give your advice a try.

I've attached two more images that show the way the system is currently set up and the way I'm understanding the way you are suggestion. Does that look correct?


The way I have it now using the aquastat's transformer:



New way with separate transformer:
 
  #6  
Old 12-31-16, 12:09 PM
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Yes, that looks correct. Good luck with your project!
 
  #7  
Old 12-31-16, 12:41 PM
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Thanks Carbide!!

When I get back over there this week to work on it I will be sure to report back with the results.

Hope you have a great new year!
 
  #8  
Old 01-05-17, 03:30 PM
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Just got home from my friends house and everything is working perfect!!

Thanks again for your help, CT!
 
  #9  
Old 01-05-17, 05:03 PM
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Glad to help...thanks for circling back with an update
 
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