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Boiler protection Delta T pump for bypass with Delta P pump for the zones

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SuperTech
SuperTech Member Posts: 2,186
Ever since I found evidence of flue gas condensation on the outlet of my chimney and my chimney base I have been pondering solutions for the situation. Here's my current idea. I have 1 1/4" supply and return mains, I was thinking about piping in a 1 1/4"x1" tee on my supply and return and connecting a bypass pipe with a Taco Viridian VT2218 on it. I'll set the Taco on setpoint heat with boiler protection mode so it speeds up flow until it approaches the boiler protection setpoint at which it will stop pumping. My system pump for the zones I'd like to be a Grundfos Alpha to modulate the flow with a call for heat on the individual zones.
The Viridian will be wired into the system pump terminals on my Tekmar 304V zone control panel, the Alpha wired to the aquastat.

Will the two pumps work in sync with each other? Should this setup provide adequate boiler protection? I like the idea of something more sophisticated than a balancing valve, and this would be much less expensive and easy to install on my boiler then primary secondary piping, a hydro separator or a Thermostatic bypass valve.

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  • Gordy
    Gordy Member Posts: 9,546
    edited November 2018
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    No. Not unless it’s piped primary secondary.

    What you describe is a simple boiler bypass. Which usually works pretty well with a system pump depending on type of connected radiation.

    Why not use a 3, or 4 way valve?

    It’s early though maybe I’m not putting the whole thing together in my half caffeinated brain yet :)
  • SuperTech
    SuperTech Member Posts: 2,186
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    The examples I see in the manual for the Taco Viridian show two examples of it being used as a bypass pump and they are both piped primary secondary. Given the current configuration of my existing piping it would be difficult to add in both a bypass and a boiler loop. My idea was to pipe in just a bypass pipe between the supply and return, and have the Taco decide how much flow is between the two based upon return temperature. Once everything is up to temperature, the bypass pump would stop and all flow would go through the zones.

    Does anyone think it's feasible?
  • SuperTech
    SuperTech Member Posts: 2,186
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    I ran this idea by the good folks at Taco. They say it's 100% good to go without the necessity of primary secondary piping. 👍.

    Time to go shopping!
  • hot_rod
    hot_rod Member Posts: 22,260
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    depends on the mass of your system, put some numbers to it. What type of heat emitters, again?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gordy
    Gordy Member Posts: 9,546
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    Something has to give. In my mind it will be a slower response to reach set point.
  • hot_rod
    hot_rod Member Posts: 22,260
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    SuperTech said:

    I ran this idea by the good folks at Taco. They say it's 100% good to go without the necessity of primary secondary piping. 👍.



    Time to go shopping!

    Tell me how a bypass pump, VS or not increases boiler supply temperature to provide that mix?

    Remember the heat emitters are in charge of the boiler operating temperature, unless you can disconnect the two, how does the boiler warm to provide mix to the return 65F, especially if the boiler is starting from 65F. A 65F boiler with 65 or colder return, cannot add up to 130?

    Or do you plan on maintaining 180 in the boiler 24/7 and have enough HP to overcome a dump of cold return.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gordy
    Gordy Member Posts: 9,546
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    I don’t see how that would work with out primary secondary. You have two circulators operating at the same time........

    Both vs......