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Wiring for pumps and zones combined...

I have a system where 2-3 zones are on a pump, but it is 8 zones total. The end result is that it has 8 zone valves and 4 zone pumps, plus a boiler pump.

It is all manually wired with individual relays, transformers, etc - and very hard to maintain because there are no status lights and it's near impossible to trace wires.

As part of replacing the boiler, I want to change the wiring to two Taco EXP 4-zone valve controllers (master/slave if you are still allowed to say that), and a Grundfos pump controller.

I have enclosed an image of the zone to pump mapping.

Normally I would want the pumps to only turn on once the zone valve signaled that it is open, but I am not sure how to wire for that given I am using a zone controller.

It doesn't really matter because I am going to change the old Taco pumps to Grundfos Alpha smart pumps with constant pressure, so should I simply just jump the input TTs as needed and not worry about waiting for the valve to open since the pumps won't actually turn on until they sense a pressure drop? Arguably I don't even need a pump controller and can just have the pumps hardwired on all of the time.

Six of the valves will be Honeywell that open in 15 seconds. Two will stay as Taco Gold that take much longer.


  • Jamie Hall
    Jamie Hall Member Posts: 22,078
    That junction box -- to reference another thread -- is why inspections are needed...

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • rsilvers
    rsilvers Member Posts: 182
    Not a thing is labeled, and this is way too hard to trace the wires.

    I think it's allowed to mix 24v with 120v as long as the insulation on the 24v wire is rated for 120v or more. But yes, I want to remove it all and start over, even though it is functioning and it would be much easier and cheaper to just swap the pumps and zone valves and not change any wires. It will cost me about $600 in parts and many hours of time to make this arguably unneeded change, but I can't resist doing it as it offends me.

  • hot_rod
    hot_rod Member Posts: 20,725
    I have been running Alphas constantly powered since they first came out and have not had any issues. Yes they do cost some power in sleep mode, 4 pumps powered maybe 40w. I suppose you could unplug them in the summer months 

    Even the  slow opening thermoelectric zone valves allow flow to start passing after 15 seconds or so, and slowly open to full flow, they work fine together, same with radiant manifolds with low current, slower acting, thermal actuators. Caleffi has been supplying manifolds with delta P circs for maybe 20 years now, the Euro market was first to adopt ECMs to work wit TRVs. 
    Your plan is solid 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • rsilvers
    rsilvers Member Posts: 182
    Ok. I will use the pump relay because it will save some power, but I won't worry about if the pumps get power right away or not.