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Piping - will this work?

Mark Walnicki
Mark Walnicki Member Posts: 21
in THE MAIN WALL
Okay, I did the best I could with the picture in mspaint. I hope it looks okay and most of it is self-explanatory. Here's a few other specifics: Where the H,C, & M are on the drawing is supposed to represent the three way mixing valve. The piping from the boiler to the 3-way mixing valve is 3/4" copper, about 100' total for supply & return. Radiant loop is hooked to the mix port. 280' 1/2" pex suspended tube in the radiant zone. Taco 007 circ.

Obviously things are left out for clarity, and I'm not wondering about control strategies yet, for now just wondering if things would flow as they're supposed to, if it were piped like this. Thanks.

Comments

  • kevin
    kevin Member Posts: 420
    Mark...

    it funny I have a similar situation. What is driving the "primary" loop? Pump? Zone valve? Seems to tme the two zones piped as you have it might fight w/ each other and get little flow through the mixer....If you pulled the supply and the return off similar to an Injection loop then piped it into the mixer it would work better...I think...lets see what the others say..kpc
  • zeb_3
    zeb_3 Member Posts: 104
    If I'm seeing you correctly

    you have a non-p/s pipe set up. I've seen this work on quite a few jobs. Just looks funny all by itself w/ no other zones. I'd be concerned on thermal shock on your boiler(cold, untempered return water).
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    zeb's

    got it. Besides shocking, I would expect short cycling. I have concerns about using the 007. What was the flow rate and head?

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  • Duncan_4
    Duncan_4 Member Posts: 4
    What will happen ?

    What will happen when the boiler temperature approaches the setting on the mixing valve?

    Answer: the hot port on the mixing valve will close down, and there will be no circulation through the boiler.

    Don't have a way of posting a drawing now, but I'm sure someone will come up with it.
  • John@WattsRadiant
    John@WattsRadiant Member Posts: 49
    Piping

    With no boiler pump, the only water that will flow thru the boiler is what the 007 pulls from the HOT side of the mix valve, which won't be much if it is a non-condensing boiler and you're doing a radiant slab. Also have no hot boiler water to mix with cool radiant return will mean condensation problems with boiler. I would expect boiler short-cycling and too cool return water to boiler. A boiler pump would solve both of these problems.
    John
  • Unknown
    Unknown Member
    Hi Mark

    I'd do it like this if it is a cast iron boiler. I'd keep the tees right together.

    I drew in a boiler pump to keep the confusion down. I feel you need one.

    Noel
  • rich_16
    rich_16 Member Posts: 15
    piping

    Can someone send me a piping diagram for a hot water system with two boilers. Thanks
  • rich_16
    rich_16 Member Posts: 15
    piping

    Can someone send me a piping diagram for a hot water system with two boilers. Thanks
  • Chris Maderia
    Chris Maderia Member Posts: 120
    Piping

    Take out my Motorized 3-Way and add a boiler by pass. This is for a multiple radiant project with no boiler protection needed.
  • Mark Walnicki
    Mark Walnicki Member Posts: 21
    Thanks to all!

    I surprised myself by being very nearly on the right track, but I couldn't have done it without all the input! I can see clearly now... and I see a boiler pump being added to the recommendations. That's the easy part. Now getting them to go for the right controls...
  • chris smith
    chris smith Member Posts: 39
    very crude

    wish i could draw better on this thing

    chris smith

    paradise porter maine
  • chris smith
    chris smith Member Posts: 39
    crude

    closely space all tee's

    chris smith
    paradise porter maine
  • hot_rod
    hot_rod Member Posts: 23,401
    right on Noel

    you need to have flow across the two tees where the 3 way connects. The 3 way has to see a constant hot supply to operate correctly. Even with a tight tee space as Noel shows I would still highly recommend a check in the pump, or piping to the radiant. Especially if it is mounted above the heat sourse as in these drawings. The warmer, water will ghost it's way up to that radiant loop, from my experience.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • pete waters
    pete waters Member Posts: 1
    piping of hot water coils

    hi,
    i have a a/c system with three hot water coils added to ductwork, old system has 3 way valves hooked up to each coil for three zones, building has been rehabbed and now i would like all three to work as a 2nd stage for heat they have baseboard heat but not enough on cold days, i was thinking of running a primary loop with monoflow tees to coils, primary loop is 1-1/4 piping but coils are only 1/2 piping. air handler is a 10 ton blower. thank you for your help
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