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Does this look right?

Thanks for looking Mark. I guess what confuses me is why two pumps are being used on the secondary side?
Would this be so that the system can remain circulating constantly and only add heat at the set temperature when called for by the stat?

I'm told the system will run on outdoor reset. I don't see how that would work if a non-electric thermostatic valve is controlling the temp of the supply water.

What am I missing?


  • tommyg
    tommyg Member Posts: 9

    I have a ton of respect for all of the pros on the wall and thoroughly enjoy reading your comments/analysis of different peoples problems.

    Here's mine. The first problem is that my contractor is so busy with emergency calls that its taking weeks to get my Munchkin installed and running. I'll worry about that one.

    My question is about the way he has it piped to this point. He allowed 2 sets of tees - one for a high temp loop to serve a manifold for panel radiators and a second set for a radiant manifold.

    I don't understand what's going on with the radiant loop. It seems he's installing an injection pump into the supply side (top) of the manifold and a circulator on the return side (bottom) of the manifold. As you can see from the photos it's not complete yet, but I don't understand the purpose of the three way valve or how he plans to finish what he's started.

    Can anyone confirm that what he's doing makes sense?
  • Mark Hunt
    Mark Hunt Member Posts: 4,909

    Those 3-way valves are what he is using to control the water temps to the radiant, he is not using injection.

    Mark H

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  • Cliff Brady
    Cliff Brady Member Posts: 149
    Constant ciruclation yes

    which is a nice thing but a fixed mixed temp does seem contrary to using a fixed three way mixing valve to 'ride' the reset curve, but with the injection mixing and constant circulation it should even out well. It is a good question. Ask your installer.

    Nice propress work. The only issue I see is there are static pressure requirements for Taco pumps mounted horizontally. You may ask if those are in spec.

    Is he using the Munchkin Vision One control to provide outdoor reset through flame modulation? It's the way to go.
  • Josh M.
    Josh M. Member Posts: 360

    Only one pump is needed for a three way mixing valve. I think it is a waste of energy to have two. Also pump in primary loop is not in right location in relation to the air scoop and expansion tank. I would recommend 12" downstream of the expansion tank.
  • Tom Giedraitis
    Tom Giedraitis Member Posts: 44

    I wondered if anyone would mention the pump location, I'm not crazy about it either based on what I've read here and Dan's Books.
  • Tom Giedraitis
    Tom Giedraitis Member Posts: 44

    No, I don't believe he's using anything more than the 925 controller.

    I asked for a piping schematic which I was told he was working on long before I placed the deposit. Then I was told I needed to get the work booked before I'd see any drawings. Ultimately I received no drawings and was just glad they showed up to start the day that they scheduled. Unfortunately the frozen pipe and no heat calls have made it seem like the job will never get done.

    Can the 007 be used for Variable Speed Injection?

    Thanks for the note about the horizontal pump mounting, I'll ask.

  • Josh M.
    Josh M. Member Posts: 360

    You bet a 007 can be used for variable speed injection... Well if he has problems with air we will know where the contractor went wrong huh?
  • chuck shaw
    chuck shaw Member Posts: 584
    According to HTP's

    piping diagrams, that is exactly where the circulator belongs.


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