need help wiring taco zone valves

I'm trying to add a 4th zone to my heating system. Currently each zone has its own circulator pump; two of which are wired up each using their own honeywell r845 and the third uses a taco sr501. The zone I'm trying to split is wired up via one of the honeywell 845. I got everything plumbed and am using 2 taco 571 zone valves.

The best I've been able to get so far is that when either of the two zones call for heat the circulator pump turns on, but the boiler doesnt fire and the valves do not open.

If I revert back to how it was originally wired (as a single zone with a single thermostat) then everything works fine again. So it seems the honeywell 845 is working properly.

The way it is now, 110v comes into lug 1/2. 1 is jumped to 3. 2 and 4 are out to the circ pump. 5 and 6 are out (in theory to TT on the boiler?...but thats a bit confusing for me as those two low voltage wires come out of this box and work their way back through the other honeywell 845 and the taco sr501).

I've been trying to test by looking for 24v out of the honeywell 845 but get 0 voltage across the TT thermostat lines, and 0 voltage from the 5/6 low voltage outputs. But the thing works so obviously I'm doing something wrong! (as expected I also get 0 v at the taco zone valve 1/2)

The only thing I haven't tried is using the 3/4 out of the honeywell instead of the 5/6 when wiring the taco zone valve. But since that seems to be the line voltage going out to the pump that doesnt seem like something that I should be doing.....or am I way off there?

 

Welcome to the forums.

So you want to use 2) Taco 571's on 1) R845 ?
Really not a proper installation. The R845 is only set up for one thermostat and one circulator. There is no 24vac output for zone valves. You would need a separate transformer to run the two zone valves. Then the R845 requires a dry contact closure (like a thermostat) to activate. When you use the three wire 571 valves..... there is no isolated contact.... so you would need an additional relay. Could be tried without the relay first.

 

I,
How are you wiring your zone valves. They need their own 24V transformer.

I'm assuming your t-stat goes to TT on the 845 now. That will now go to #1 & #2 on your zone valve and then you will run another stat wire from #2 & #3 to TT on your 845.

5 & 6 on your 845 can be low or line voltage. Do not use 3 & 4. You don't have to touch any of the wiring on that 845 other than the stat wires.

Your wiring circuit for the ZV's is as follows.

From the trans. to stat (either term.), from stat to #1 on ZV. From #2 on ZV back to trans. ( that complets the stat circuit and opens the ZV)

Run a new stat wir from #2 & #3 on ZV to TT on 845. That will pull in relay and activate 5/6 on 845 to TT on boiler.

That you start the boiler and pump and send up heat.

Once wired, with the stat turned up check your ZV by pushing the lever down. It should not have any resistance if it is open. Once open it activates an end switch to 2 & 3 and start the boiler and pump.

Hope this helps a little.

 

I didn't realize I would need a separate 24v transformer and assumed the R845 was able to do this. @spott you're correct about how it's currently wired up.

So its as simple as grabbing a 24v transformer off the shelf at home depot, wiring it up to the same source going to the 845 and then use that output?

I do also have a Taco sr502 two zone switching relay. I got this when I got the zone valves and assumed it was proper. But later realized it only has two wire outputs and I should have sourced a zone valve control with the three wire outputs instead. Is there a way to properly use this with the two zone valves?

 

No.... that controller has two wire outputs that connect directly to the 120v circulators. You'd need the correct model.

taco-hvac/uploads/FileLibrary/SR502.pdf

 

As PJ said that is the relay for circulators.

The one you need is for Zone Valves. It is ZVC403-4.

This sight might help with your options.

http://www.supplyhouse.com/Taco-ZVC4...-with-Priority

Scroll down to the installation guide to see the wiring.

As far as your transformer goes it does not have to be wired into the same circuit to pick up the 110V feed. Any 110V feed will do and then wire the 24V circuit into yours.

 

Unfortunately I did the majority of my research only after I sourced second hand parts and am feeling a bit foolish. Its now completely obvious to me that I needed a zone valve control board to do this instead of the zone switching relay that I got (anyone looking to buy one?). I completely misunderstood that I would need a separate 24v transformer to power the zone valves I got but I think I know what needs to be done now. Is there any particular type or brand of transformer known to be better or worse than any others?

Sorry if this is a bit of a stupid question, but should the new 24v transformer get mounted in a box? I feel like thats likely the right way to do it; but I know I've seen transformers simply mounted to a wall in homes in the past. In theory whatever 24v transformer I end up getting is capable of running as man as three taco zone valves total?

 

It's not stupid. You need to know.

You'd want a 24vac 40va transformer. The type that is mounted on a 4" square plate is ideal for what you're doing. They also make one that installs in a 1/2" electrical box ko. Either would work.

 

Thanks for making me feel a bit better. I know I've seen the 4" square plate before (doorbell transformers I suppose?)...seems odd/wrong to me to have any 110v connections not contained within a box though. I suppose my final decision will be made by whats available off the shelf when I get to depot after work today!

I know they'll have this one in stock and it seems like that might be the only option at my local store. Just want to make sure I'm heading in the right direction here and confirm that I can surface mount this thing without a box (and/or if I can find a box it'll fit in that there is nothing wrong with using a box?) https://www.homedepot.com/p/Honeywel...T72D/202264717

 

It looks like they sell a 4" sq. cover plate for that trans. that will fit on a box

I realize this may be a little late but I noticed the price at HD and thought it was high but if you need it now it is what it is but you might want to check out this sight in the future.

http://www.supplyhouse.com/White-Rod...nt-Transformer

They have other options if you go there and type in what you're looking for in the search box.

In this case type in transformers and you'll get different options.

 

I am familiar with the site.....its where I sourced the toe kick hydronic heaters that I'm using for this 4th zone actually. I'm still debating if I should spend the few extra bucks just to have it in hand today or if I should save a couple of bucks and prolong the project. Appreciate the help and the advice for sure!

 

AT72D... that's a good transformer. I was going to leave that link for you except for some reason the depot price seemed excessively high. That is a multimount transformer so you can install it in any 1/2" electrical knockout..... or on a 4" square plate with 1/2" ko.

 

Appreciate all the help. Got it all wired up correctly last night and everything works as it should now.

I hadn't realized what that screw was for...I thought it was a ground at first!

 

IK,
Thanks for the update..