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Piping 2nd Zone for Basement

Torfit Member Posts: 2
I'm adding a 2nd zone for my basement, and I want to make sure I've planned the piping, valves and pumps properly.  Does this look correct?

My original installer has left the two tee'd off connections and valves for the new zone and I plan to add the new zone myself. 

Is my new pump (Taco 007) directed correctly (pump away) and will my bypass create problems with flow in my main upstairs zone?  I've included a purge valve in the new zone to remove air from the basement zone.

Can I get some expert opinions?


  • Ironman
    Ironman Member Posts: 7,350
    edited June 2011
    Changes Needed

    Your diagram needs a couple of changes to work.

    First, the return from the new zone needs to connect down stream from the circ of the existing zone, not above it as you're showing. In other words, connect it between the boiler and the existing circ.

    Second, you need a flow-check in each loop to prevent reverse flow when the opposite circ is running. You can use circs with internal checks or install external flow checks.

    I can see no purpose for the bypass in the new loop. If your trying to protect the boiler, the bypass has to go in the near boiler piping, before the Tee's in the supply and after the circs in the return. In other words, between supply header and return header.

    If you're going to leave the expansion tank connected to the return, then the new circ should go in the return down stream of it. That way both circs will be pumping away from the PNPC (point of no pressure change).
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Torfit
    Torfit Member Posts: 2
    Piping 2nd Zone for Basement

    thanks for the quick reply Bob.

    Actually, I made an error in my drawing...the water supply and expansion tank connect at the boiler supply (above that T), not at the boiler return.  The scale of my piping diagram isn't really that accurate, but was easier to draw it that way.

    I've been told that I should wire the 2 circulators to come on together (or only the main one if there is no call for heat in the basement thermostat) so that I don't short cycle my boiler.  In other words, Zone 2 would only receive heat if there is also a call for heat in Zone 1.  My basement is better insulated than the rest of the 1930's house, so presumably I would need heat more upstairs than down once this is all connected.

    As you can see from the pics I've attached, it would be a pain to repipe the existing circulator somewhere else if necessary.

    The bypass is indeed near the boiler, and works fine within the existing piping configuration.  Do I have to move its location in order to add the new zone piping?

    Does this change your opinion of whether this should work?  The existing main circulator is a larger B&G circulator and I was planning to add a Taco007 for the 2nd zone.
  • Ironman
    Ironman Member Posts: 7,350
    Not Piped Right for 2nd Zone

    You can't tap the 2nd zone off the bypass as the installer tried to leave it. The way it's presently set up, the 2nd zone would bypass water around the boiler and not heat. Remember,  water takes the path of last resistance. And again, the return from the second loop would have to connect below the existing circulator, not above it as it's presently tapped. You're gonna need a bit of re-piping to do this.

    In answer to your last question: No, each circ should be controlled separately by its own T'stat and relay.

    Also, be aware that by enclosing the boiler you will be starving it of combustion make up air and provision will have to be made to correct that. Either transfer grilles high and low or outside air ducts high and low.

    It looks like this is a converted gravity flow system. How many floors upstairs?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
This discussion has been closed.