Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

Circulator/Zone Valve Layout & Location

Brent H.Brent H. Member Posts: 83

My current forced hot water heating system consists of 3 zones each with a circulator on the return and flow-check on the supply. I'm getting ready to tie in a large addition that will have 3 zones. I ran a 3/4" supply and return line(Fostapex) to the addition and plan to put the zone valves in the basement of the addition. Now my questions...... should the circulator be put on the return side like all the other circulators in the house? Should the zone valves go on the supply side or the return? I'm thinking of trying a Grundfos Alpha circulator for this application. Also, I'm hoping to replace the boiler next year and plan on piping it "Pumping Away". Any help/ideas would be appreciated. I've learned a great deal on "The Wall" and enjoy reading it daily.



  • hot rodhot rod Member Posts: 7,014
    personal choice

    I like to pump the supply, zone valves on the return. Most pumps have the check included or installed in the volute, so you have check protection on the supply with the pump.

    With zone valves on the return you have 100% protection on the return side.

    So you now you get S&R flow protection.

    Will the Alpha run all the zones in the house, or just the addition?

    Depending on the boiler and nearby boiler piping, as well as the load size, you may be able to run the entire system on one circulator.

    I've been running Alphas for several seasons on my home and shop, it's a great pump for zone valved systems.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Brent H.Brent H. Member Posts: 83
    Quick Followup

    Thanks for the suggestions.

    Is there any problem with having pumps on both the supply and returns?(Existing 3 are on the returns and the addition will be on the supply)

    Also, I bought ball valves to pair up with each zone valve. Which side of the zone valve are they most commonly installed on?

    When I get a new boiler, I may look into whether the Alpha could drive the whole house.
  • hot rodhot rod Member Posts: 7,014
    edited October 2009
    either way

    should work fine. Really no need for ball valves at the zone valves. Most zone valve brands have actuators that pop off for replacement if needed, so the valve bodies should not need isolation.I would include some Webstone valves with the side purge cock so you can get a good initial purge. Either one on the common header or one at every zone connection.Hard to say without seeing your current or intended piping. I assume something like this? The black lines being the new addition?

    I would add isolation valves at the pump. hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Brent H.Brent H. Member Posts: 83

    Hot Rod,

    Thanks for the help. The drawing is pretty much dead on with what my current system is. Adding the additional circulator shouldn't be too bad of a job since last time I added one I left fittings with plugs to allow for futur expansion. It may look a little convoluted since the circulator will be up by the ceiling since that is where all the supply piping is currently.

    One question, how are most people wiring these Alpha pumps in? Are they wiring an outlet off the switching relay or cutting the plug off the end and hardwiring a cord into a box?

    Thanks again.
  • hot rodhot rod Member Posts: 7,014

    methods are used to wire the Alphas, the next version will have a junction box. No need for a relay with an Alpha, they just go into low power consumption, no flow condition when the flows are all shut off.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Brent H.Brent H. Member Posts: 83

    While it is nice that I don't need a switching relay, I'm not quite sure the easiest way to tie the zone valve contacts back to the boiler to turn it on when the zone is calling for heat. My current system has a tankless coil and has 3 switching relays setup in a DHW priority mode which complicates matters a bit. I'm wondering if it would be easier to just install another switching relay. Thanks.
  • ChasManChasMan Member Posts: 353

    My understanding (so far) would be that If you allready have the spare zone on your switching relay you can just hook up the end switches as you normally would. There is just no need to wire the pump in. If you don't have a zone panel then you can just paralell all your end switches and jump TT with that. The pump will sense the open valve and start more flow.

    Im not sure I like this idea much. Priority circuits would need to shut off zone valves. A bunch of rewiring at least in my case. Is there any problem with switching the pump off a relay? Grundfos literature dosn't say one way or the other.
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!