Convert from zone valve to zone pumps

Discussion in 'HVAC Heating & Cooling' started by rockycmt, Jan 2, 2013.

  1. rockycmt

    rockycmt New Member

    Messages:
    129
    Location:
    New York
    Right now I have a 1 punp 3 zone hydro. One HW and 2 living. I want to add a radient underfloor loop via mixing valve. While doing this it seems cleaner to just do all the zones with new pumps and a 4 zone switch relay. I have the pumps already so the cost to convert is not an issue. The question I have is:

    do the pumps for each zone act as valves. What I mean is... If a zone is not active and another is.... Is anything needed to isolate the zone as a zone valve does? Or will the pumps do this? (i.e. when pump is not moving it is a closed zone) All the schemas I have seen show the boiler --> pump --> zone --> boiler.

    This is a nice little spring project I have planned.

    Curently I have one zone running way too many radiators. 2 floors on zone, small room on zone 2, HW on zone 3.

    I want to clean this up and have living spaces on 1, bedrooms on 2, Basement on 3, HW on 4.
  2. Dana

    Dana In the trades

    Messages:
    2,924
    Location:
    01609
    You'll need a check valve in series with each pump, since the pressure differences created any one pump driving from the manifold will induce a reverse flow on the others. On very high head loops that may never present a practical issue, but on shorter hydronic loops that back flow can create unintentional heating of the "off" zones.

    When reconfiguring, try to avoid micro-zones, since that causes short-cycling efficiency losses and unnecessary wear & tear on the boiler. If your current smaller zone 2 has just a low-mass stick of fin-tube for a heat emitter, it's almost certainly short-cycling on that zone. Zoning it by floors is usually pretty reasonable, as long as the room-to-room balance has been properly dealt with by load-proportional room-to-room radiation sizing (based on the room-by-room heat loads, not the square footage of the space.)
  3. rockycmt

    rockycmt New Member

    Messages:
    129
    Location:
    New York
    I understand. The Taco pumps I have have the check built in. IFC. so that should cover that.

    TY for your reply it was dead on what I was looking for.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    I question whether a "4 zone switching relay" will do what you want it to, because that usually controls ONE pump and four low voltage zone valves. For your system, you will probably need four thermostats and four pump control relays, and EACH of them would need the contacts, in parallel, to operate the boiler's burner.
  5. rockycmt

    rockycmt New Member

    Messages:
    129
    Location:
    New York
    I disagree. This is exactly what I will use.
    http://www.pexsupply.com/Taco-SR504-4-4-Zone-Switching-Relay
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