Circ control options

Mr Bill W.

Need help wiring multiple circs / zones. Have a WM Ultra with Priority DHW and two zones. Zone one uses ZV and boiler circ while zone 2 uses ZV and second Circ. This system also has a Taco zone controller. First I thought about a 24v switching relay switched by the zone controller to power the 2nd circ. but this results in the circ continuing to run during DHW call. 2nd idea was to switch off the boiler circ with a 120v switch but this caused the zone 2 pump to run when zone 1 calls for heat. What is the best way to wire this. I'm new to this and have found this site informative and helpfull. Thanks for any ideas.

Bob Sweet

Bill

If I understand you correct, you'll need a seperate pump to run zone 1, the design behind the Ultra is to utilize primary secondary piping the boiler pump is designed for the primary loop only, not zoning a secondary circiut.

I'm not sure what your stratedgy is but, why use two circ's on a two zone system why not two ZV on a single pump secondary. Control strategy then becomes simple, 1 relay controlled off primary boiler pump control.

hr

That does get a little involved

My partner Scott has a really good method using 3 pole relays. As you know that primary circ has to come on with any zone call for heat. Any zone has to also call on the boiler tt terminals. Thirdly the zone circ, and or, a ZV needs to be powered.

Depending on how you piped the DHW, wire as follows. If you used a second, properly sized, circ for dhw, with the checks in correct locations, then use the factory connections for DHW aquastat and DHW pump. This automatically drops power to the primary loop circ and allows full boiler output to the indirect tank.

If you run the indirect off a primary loop then, again, you need to fire the DHW circ, the boiler primary loop circ, and the boiler call for heat. This is where the 3 pole relays work to keep all these various electrical circuits friendly to one another.

Kinda of hard to explain, you really need to sit down and draw it out.

Leave a copy of that schematic for the next service guy!

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Mr Bill W.

Thanks for the feedback. The DHW is wired to the Ultra per the instructions, with zone 1 on the primary loop and zone 2 on the secondary. Below is a drawing of the piping. of intrest zone 1 is baseboard & zone 2 is radiant, no mixing max outlet temp set to 150 in the ultra control I think that I somehow need circ 2 to only run when zone 2 calls for heat. Thanks for all your input and ideas

hr

I couldn't open that doc

can you try another format?

The Control Supplement does a pretty good job of showing and explaining various, but not all, wiring options. It does mention the possible need to add another relay in the "Wiring a system circulator" paragraph.

It's hard for a manufacture to cover all the wiring options. Perhaps try contacting Taco for some interface assistence. Dave Sweet, at Taco, can figure that stuff out in a heartbeat and send a Taco solution. It may, and probably does, need some additional relay controls as I mentioned above.

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Mr Bill W.

new try with drawing

Bob Sweet

Bill

It might work, but you are straying away from the Manu. recommendations. Zone 1 imo will become a problem for the system.

Bill W

So the best option would be to move zone one to the secondary loop? this would leave the DHW on primary and the 2nd pump would power both zones thru isolation by zone valves. My intent is to change zone one to a two zone staple up in the future

Bob Sweet

Bill

imo thats the way to go. You wont interfere with the flow requirements of the Ultra, and control wiring will be a cinch.

hr

I don't like it

I see no reason for there to be flow to zone 1 or the indirect? Is it too late to repipe?

My suggestions, I like to see the indirect with it's own pump paralel to the boiler, as the manual shows. It could be run with a ZV off the secondary loop, but it will not perform as well.

I have a couple drawings depending if you want to stay with two circs, or three. If you pump the indirect, pay attention to the circ required by the installation manual. You need to flow the boiler according to spec, as they have a bit of pressure drop.

The Weil drawings are correct, although a bit hard to read with dashed lines. They should have hired Siggy to do some nice clear, color drawings, as they have in the past

Number 1 would be very simple to wire, without DHW priority. Just use the Taco ZC box. With DHW priority you might need an additional relay to drop the ZV 1& 2 out while DHW calls and recovers. Probably a simple double throw relay. I prefer the ZVs onnthe return to eliminate noise ot hammer issues. Personal preference really.

I prefer # 2 to give the indirect the most bang for the bucks, performance wise. It also allows you to use the factory supplied wiring terminals.

At some point it may pay to get some help with the wiring, it's a fairly simple job for an experienced contractor with all the right stuff on his truck

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Mr Bill W.

last questions (I hope)

Thanks for the input and ideas. Looks like I need to do some repiping. Last couple of questions, I hope. First on HR's drawing his symbols, I think the x are check valves but not sure what is just before the pump. Second for zone 1 can I just move the supply to The secondary loop and leave the return at it's current location. the indirect is in parallel with its own pump just like HR's drawing #2. Agene thanks for the advice and help with this

hr

Bite the bullet and

start over I really can't tell exactly what piping arrangement you have going on. It MAY be a primary secondary IF the tees are spaced closely at the interface to the upper zone piping. If not you have some series and paralel going on without any supervision!

If you have the installation manual, page 15 describes it better than my crude drawing including descriptions of the components. The manual encourages Primary Secondary piping to assure the boiler gets adequate flow. I would agree with that request with this specfic boiler. It NEEDS to be pumped as they show.

You can print the manual from www.weil-mclain.com if you are missing pages.

If you pipe and wire as the manual shows you will a troublefree system.

Trying to modify what you have may, or may not work out. Without pipe sizes, dimensions, pump spec, etc, it's hard to tell from here.

If you pipe it as shown in this drawing the wiring will be very simple also, most of it is already done inside the boiler and waiting for you.

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Joe Mattiello

Taco ZVC404 will work

If I understand you correctly, you have 3 pumps, and 1 zonevalve. The ZVC404 4 zone capacity board will work for you. The heat zone with the dedicated pump can be wired to zone one. Bring the thermostat wires to TT terminals on zone one and the zone valve to the corresponding terminals at the bottom. Use Zone 4 for the indirect water heater. Install a jumper between terminals 3, and 4 at the corresponding terminals at the bottom just like we show in the instruction sheet. Now the circulators, bring a hot leg into one side of the extra end switch, and bring a jumper over to the common terminal. Place one leg of the domestic water pump on the N/O terminal, and one leg of the pump for zone one on the N/C terminal. The primary pump which has to operate when either of the 2 zones call for heat can work off the boiler aquastat,. Alternatively, you can use the dead side of the extra endswitch on the ZVC404 if you can’t use the aquastat/relay control on the Ultra. For you convenience I have attached the Taco Zone Control wiring Guide. Please refer to page 26 for a wiring diagram, and advise if you have additional questions or concerns.


Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

Bob Sweet

I dont think the biggest concern here is the control wiring

more so the flow requirements of the boiler. The boiler primary pump needs to be dedicated for the boiler only. All other flow requirements need to be met with additional pumps. The boiler manuf. drawings are explicit as to what is needed.