I'm doing a home renovation, and I have a question I'm hoping somebody can answer for me. I'm not a pro at any of this.

My plumber installed a Weil-McLain Ultra 105 Series 2 Gas-Fired Water Boiler and a Plus 40 Series 3 Hot Water Tank. I'm the electrician because I know a little about wiring, but I don't know about the relay that seems to be needed for this setup.

According to page 5 of the Control Supplement Manual (see http://www.weil-mclain.com/downloads...ontrolsupp.pdf) there is supposed to be a relay to control the System Circulator pump. That pump is a Taco Cartridge Circulator Model 007-F5. Can somebody tell me what type of relay is recommended and how to wire it in? The plumber dropped on me a Honeywell R4222D 1013 DPDT relay, but the instructions really confuse me since they seem to be for fan operation. This relay also doesn't have the plug-in receptacle or cover; it's a bare relay.

Any help would be greatly appreciated.

 

Is this for a single zone system? By zones I mean heating zones, not the indirect.

 

No, it's a 4-zone system, controlled by 4 Honeywell V8043E1012 motorized control valves and 4 thermostats that I don't have yet. The circulator pump that the relay controls pushes the hot water through those valves.

If I need something else like an Aquastat (Honeywell L8148J) I'd be open to using it. Or maybe the Weil-McLain WMZ controller, but I don't know how that would control the circulator pump either.

Thanks again for reading this.

 

The zone controller should control the circ on the heating loop. That'll be your relay...

 

OK, I think I have it. If I were to go and buy a zone controller, let's say for example the Taco ZVC404 (see http://houseneeds.com/shop/manuals/taco_zvc404.pdf for a wiring diagram) then I can connect the 4 thermostats into that, not use priority since that's done by the boiler, and run the system circulator pump off the end switch area of the board, correct?

Thanks again for reading.

 

You would have the t-stat leads going in, wires to the ZVs going out. The heating loop circ would be wired in a manner like they are showing for the optional aspect.

Then tt leads would go to the boiler.

The boiler's controller would have the indirect wired directly to it and not the zone valve controller. The boiler's controller handles an indirect perfectly.

The ZVC's job would be just to energize the heating loop pump if any t-stats (and their related ZVs would open) are calling for heat. The boiler would control the boiler loop circ and the indirect's circ.

 

Makes sense, thanks much!

 

I thought about this some more, and now it's not making sense.

The system has 3 pumps. The first is a boiler pump. The second pump is a circulator pump for the indirect. And the third pump is for the zone valve heating. The problem is that the indirect (hot water heater) has priority. I think that if that's on, the third pump should be off. I am worried that if I install a ZVC, the priority won't work.

The boiler I have normally handles the priority. So I'm back to my original question of which type of relay should I be using to control the third pump?

I hope this is making sense and that I'm not rambling too much.

 

More information:

From the manual: "The boiler Control Module turns off space heating during water heater heating. The boiler circulator will turn off, preventing hot water from circulating to the system. The flow/check valve shown on the boiler outlet piping prevents gravity circulation in the boiler loop during water heater heating."

So it seems to me like the boiler and system circ pumps work at the same time, and the indirect (hot water) pump works when it has to.

Also according to the manual, it says not to "connect another circulator to same [120V] terminals as the boiler circulator or the DHW [indirect] circulator [because] the boiler module will encounter fuse failures." So I assume it uses the relay in question to control power from another source.

If anybody can attempt to explain what type or give a specific model number of a relay normally used for this, it would be appreciated. I'm thinking it's probably best to call a pro in to double-check any work I do.

 

Think of your system as 3 separate circuits. It's called primary secondary for a reason.

Okay, you have a heating circuit and that pump you want the relay to energize and sub sub circuits that will be controlled by zone valves.

You also have parallel circuits right off the boiler. One that links to the heating circuit, and the other that links to the indirect.

If you have a t-stat calling for heat, it will energize the heating circ, open the zone valve and send a heat call to the boiler. If the boiler is making hot water it will ignore it so that the heating circuit will still be flowing but the boiler won't be adding heat to it. Once that DHW call is satisfied, the boiler loop will connect to the heating loop.

You might even have situations where the t-stat says add some heat and your boiler will say no way its too warm out... and the boiler just won't add heat to the heating circuit but the heating circuit will flow.

 

Thanks so much for the explanation. I must have read it more than 5 times, checked the plumbing a couple times, and now the light bulb is starting to come on. I was stumped by my assumption that because the manual shows the boiler and system circulator pumps being connected together, they must operate together. Now I will wire it so the system circ pump will be operating maybe sometimes while the boiler pump is not.

The only thing left to do is figure out the electrical loads for all these pumps and switches, but I think I can do that.

Thanks again!