Adding Taco Zone Valves with R8285 Control


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Old 08-15-21, 07:19 PM
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Adding Taco Zone Valves with R8285 Control

Hello!

I've tried a lot of searching on this site and others and finally mustered the courage to ask for help...

I have a Burnham Series 2a gas boiler. I recently added radiators as part of our basement renovation, and I added zone valves to zone the basement separately from the upstairs. I added a Taco 573-2 and a Taco 571-2.

The boiler has a Honeywell R8285D-1026 control. Before zoning, my old two-wire thermostat simply attached to the R (hot) and G (neutral) terminals on the R8285.

After much research, I now understand the wiring diagram on the Taco zone valves. I recognize I need a dedicated 120 VAC To 24 VAC transformer for the zone valves. I'm planning to get this: https://www.supplyhouse.com/White-Ro...nt-Transformer

First: I have a dedicated 120 VAC ROMEX line going to the boiler. Can I add the 24 VAC transformer off that line, or do I need to tie it into an electrical line that is separate from the boiler?

Second: the Taco zone valve diagrams want you to tie your lines coming off the zone valves to TT terminals. With my R8285 control, which doesn't have TT, does that simply mean R and G? Does it matter which line from the zone valve goes to G and which one goes to R? I envision the line coming from zone valve #2 terminal to G and #3 terminal to R.

Finally: I recognize the Taco Zone Valve Control ZVC403-4 would be cleanest route to go. But if I'm already pretty clean with my wiring and am planning to get the transformer, is there any significant benefit to the ZVC? And if I were to get the ZVC, would I hook up the "Isolated End Switch" X and X to the R and G on the R8285? Does it matter which goes to the R and G?

Thank you very much for clearing this up! I've spent hours digging and couldn't quite piece everything together.
 
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Old 08-16-21, 06:03 AM
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Hi, definitely install the new transformer on the same circuit, on the load side of the service switch, how is that R8285 connected to the boiler now, some pics will help, you won’t be able to connect the valves to that R8285, I don’t believe.
Geo🇺🇸
 
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Old 08-16-21, 08:27 AM
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Photos of R8285

@Geochurchi – thanks very much for your reply! Attached/below are photos of the R8285 on the boiler.

OK, I understand now that I would add the zone valve transformer on the same circuit as the boiler, after the switch for the boiler. Given that, I'll probably need to find a spot to mount the transformer just below the R8285.

The question now is whether I can wire the zone valves – which want you to wire to TT – to the R8285 control.

Thanks for any additional help!




R8285 on boiler



R8285 on boiler



R8285 with terminals letters in white



R8285 with thermostat lines traced to R terminal and G terminal
 
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Old 08-16-21, 10:37 AM
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Hi, you are going to have to use a new Taco ZVC because you will be having 2 power sources, why not just remove the existing control and use the Taco to control everything?
Geo 🇺🇸
 
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Old 08-16-21, 06:20 PM
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The existing transformer is adequate for a couple of zone valves which take very little power.

For simplicity DH runs everything on a 24 volt 70 va transformer.... 8 zone valves & controllers, 5 thermostats, ODR and central AC control.

Wiring errors can cause problems when using several 24 volt transformers in a home.
 
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Old 08-18-21, 04:31 PM
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S,
The R8285D is only to run the boiler and not to power ZV's. You must use a seperate transformer for the ZV's. You can put 3 TACO ZV's on a 24V 40va transformer powered by a seperate 110v line picked up from anywhere. If you wired it in off the service switch on the boiler you can mount it in a 4 x 4 box and mount the transformer to that next to the switch on the side of the boiler or anywhere it's convenient.

From the new transformer it is a series circuit. From the transformer to the t-stat then from the stat to term 1 on ZV, then from term 2 on ZV back to transformer to complete that circuit, the 2 & 3 on ZV go to TT on boiler or whatever your current stat is wired to. It is the same for all zones.

What I do is mount another 4 x 4 box and bring all my wires into that and then just bring 1 wire to TT to run the boiler. Just a suggestion.

Hope this was helpful.
 
stepanek3872 voted this post useful.
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Old 08-18-21, 06:56 PM
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@spott - thank you! You answered my main question: the wires going to TT in the Taco ZV diagram should go to R and G on my 8285. Your mounting suggestion was also really helpful!

I knew that the 8285 is only for the boiler and not the ZVs. I've heard about people running ZVs off the 8285 -- maybe the 8285 transformer is capable, but I know that Burnham specifically says not to do this (e.g. the last two sentences on this comment: https://forum.heatinghelp.com/discus...Comment_922001).

But I'm actually moving forward with the Taco ZVC403-4. Probably overkill, but I think it will be cleaner and have some added benefits. And I'm planning to run wires from the isolated end switch on the ZVC403-4 to the R and G terminals on the 8285 control.
 
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Old 08-19-21, 09:38 AM
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Hi, I confused as to why you need the R8285D control if you are using the Taco ZVC, why not connect your existing Tstat into the new Taco and then run the isolated terminals from the Taco to the boiler? Check this pic out
if you have a separate zone for DHW you can use a priority zone.



Geo 🇺🇸


 

Last edited by Geochurchi; 08-19-21 at 09:55 AM.
 

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