Wiring second pump and thermostat

Brandon541

Wondering how I wire the second pump and thermostat to the triple aquastat and first pump! 

Jamie Hall

I'm sorry, but that's a bit vague. You are adding a second pump? What is it intended to do? What does the first pump do? The aquastat usually controls the boiler, but what do you want it to do? What is intended to control the first pump? What controls the second pump?

Brandon541

Sorry I’m clueless here about this stuff that’s why I’m asking. All I know is that there is 2 circ pumps that need to be hooked up. The first circ pump controls 3 zone valves and the second pump will control the newly added 4 zone valve. I know how to wire up the aquastat with one pump I just need to know how to wire the second pump through that other thing I sent (called a taco maybe?) everything is already done just replacing the boiler but when I arrived the plumber already had everything disconnected

Brandon541

Can I maybe just splice the 2 pumps together inside that taco thing? Have some BX connecting the pump inside the taco and the pump inside the aquastat with pigtails onto the c1 and c2. I want both pumps to work together 

Jamie Hall

Well... the usual arrangement would be to have the three zone valves which are fed by one of the pumps turn that pump on through their end switches or a zone controller, and the new fourth zone valve control its pump though its end switch -- although even more usually if you have just one zone valve and one pump, you'd not have the zone valve at all. The various thermostats would control the zone valves. The boiler would also be controlled by the zone valves (in your situation you'd need a couple of relays or a zone control panel), but also the aquastat. The aquastat simply tells the boiler to run if there is a call for heat somewhere and the water is too cool, and turns the boiler off if the water gets too warm.

Some of the wiring has to be 120 VAC line voltage wiring which, unless you are comfortable working with power wiring, might best be left to a professional. The control wiring might either be 120 VAC, but more normally 24 VAC from a transformer.

You don't have enough slack in at least some of the disconnected wires to safely reconnect them properly, so you may need some moderately extensive new cable.

The easiest way to do all this is using a zone control board, but unless one is familiar with them they can be a bit tricky to wire properly and your arrangement doesn't lend itself to a straightforward hookup.

Generally I'm all for DIY, but this one you are going to have a pretty steep learning curve...You might do well to find an hydronic (hot water) heating professional to come in and do the setup -- I rather gather that the plumber you had is OK with pipes, but not too happy with controls?

Brandon541

Yeah I’m a third year electrician but these controls are confusing to me when I haven’t done anything like it before. The plumber was not much help at all. I have my 120 VAC coming into the aquastat on my line 1 line 2. The burner is in the aquastat on B1 B2. Thermostat controlling 3 zone valves on T1 T2. I’m fairly certain the 4th zone valve thermostat wire goes into the taco thing. Is there anything I can do with what I have to get both pumps firing? The taco thing has a relay switch in it just like the aquastat 

hot_rod

Something doesn’t look correct with that 3 way mixing valve piping. Was that the recent addition?

There needs to be a pump on the mixed outlet, and the return from the zone needs to tee into the cold port.

Both of those circulators will need to have check valves installed at the discharge, also. It looks like one is pulling from the mix valve?

109A_5

Hello @Brandon541,
Sounds like the Plumber did not do you any favors by dismantling the working example.

I would study a manual like the one linked below for a Honeywell L8124 Triple Aquastat. Figure out what wiring diagram best represents what was originally there and where you want to go with the expansion of the added equipment. You may need to blend some of the information from different wiring diagrams to best match that system.

https://inspectapedia.com/heat/Honeywell-L8124-Aquastat-Manual.pdf

Some examples;