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Control ZV - What Tells the Boiler to Come On

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anjenaire2
anjenaire2 Member Posts: 4
in Thermostats and Controls
I am thinking about installing a modulating condensing boiler (Embassy Onex) using the Zone Valve option (see attached diagram). Currently my zones are operated with a thermostat - pump relay - pump setup (three zones, three relays and three pumps). I want to take it to five zones (with a future sixth zone) and the mod-con comes with an internal pump. I believe the thermostats would now go to a relay that tells the zone valve to open, what tells the pump to activate and the boiler to create hot water?

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  • CMadatMe
    CMadatMe Member Posts: 3,086
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    The Zone Control

    If your plan is to zone all zone valves then buy a Taco ZVC-406 or equiv. Wire the zone valves and therm per the wiring diagram and take the end switch from the zone control to RT on the boiler.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • anjenaire2
    anjenaire2 Member Posts: 4
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    Much Thanks

    So the end switch gets wired to the "RT" connection on the boiler.



    Thanks so much for the advice.
  • CMadatMe
    CMadatMe Member Posts: 3,086
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    Noticed a Note on that schematic

    States that you must maintain 100 gallons per hr flow rate? Equates to minimum flow rate of 1.7 GPM. If any of those zones are less than 17,000 btus (based on a a 20 degree delta-t) I would make sure I use a low loss header/hydro seperator. I'm not a fan of primary/secondary with a mod con.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • kcopp
    kcopp Member Posts: 4,432
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    i have a couple....

    of these in the field... pretty neat units. The tankless puts out 6+ gpm. Flow is important... I also  would reccommend a LLH or as I do 2- 1 1/4  tees,  a couple of reducing couplings and some take offs for the supply and return.... placed vertical to make a  header. 
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