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Is this system two pipe monoflo or a parallel reverse return?

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SuperTech
SuperTech Member Posts: 2,206
I'm trying to make sense of and put a name on the type of piping system used in my house, if that is possible. Some of it doesn't look right to me. I have a small loop of fin tube convectors in a room downstairs, which seems undersized because the they never heat enough. I noticed these convectors were also run with a monoflo diverter tee feeding the supply side, two diverters would have been ideal. And above this room is the kitchen, which is strangely enough all fin tube convectors as well. The kitchen hasn't been an issue but I wish it was cast iron baseboards like the rest of the house. I tried mapping it out earlier but it's driving me nuts that I can't confirm the location of every diverter tee and some of the piping I had to fill in the blank areas after I drew everything I could see.

Eventually I want to find out if my pump is sized properly, because it's not piped correctly at the boiler and I want to move it and add a diverter tee to the downstairs return tee.

Attached is how I drew it. Was the guy that made this originally able to get this to work through skill or luck? I asked a retired plumber about it and his response was that he didn't see enough monoflo systems to explain it. I saw some diverter systems in past posts but nothing seems to match my configuration. The lines drawn in marker are the emmiters.



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  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,847
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    Those are monoflow or venturi tees for sure. From your diagram it looks like a mix of monoflow and loop piping. Are all the venturi tees shown? And does each pc of radiation have them? They look like they are piped to the radiator supply. They will work either way if piped in the correct orientation. Hard to tell from your drawing.

    Or it could be a two pipe direct return with just a couple of baseboards piped monoflow with venturi tees
  • SuperTech
    SuperTech Member Posts: 2,206
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    It's hard to tell exactly what is going on. I know my sketch isn't perfectly clear. I started this to try to figure out my boiler and what is best for it moving forward, but now I have more questions than I did when I started.
    For example, only two of the corners are piped the same, despite three of them being heated by cast iron baseboards. The corners closest to the boiler don't appear to be fed by monoflo tees (I can only get to one), they are fed by the end of the supply pipes going to a 1x1/2"elbow up to the baseboards and come back into the 1" return pipe that is run underneath the baseboards. The corner in my living room had no pipe under it from what I can see and I don't know why.

    I can't understand why it was done in this manner. Why run so much additional pipe needed for the return in a Venturi/diverter tee/monoflo system? Why were the original cast iron radiators (not baseboards) in my kitchen replaced with fin tube? Why doesn't this seem to match any traditional piping scheme I look up? Why does it all work when nothing seems right? How can I improve it?
  • SuperTech
    SuperTech Member Posts: 2,206
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    For what it's worth I marked all of the diverter tees with an M on the sketch. I found none on the return lines. What looks like a tee in the center of the sketch is actually a wye with a reducing bushing in it, I'll attach a picture
  • SuperTech
    SuperTech Member Posts: 2,206
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  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,847
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    The last picture you posted is a Y fitting. Nothing special there.

    Venturi tees are usually installed on the baseboard or radiator return if the base board is installed above the main (boiler in basement radiation above boiler).

    If the boiler is installed above the main..boiler in basement and baseboard in basement with overhead piping then usually 2 venture tees are installed I on baseboard supply and 1 on baseboard return because pushing the water down hill is more difficult.

    There is no reason why venture tees can't be installed on the radiation supply and a regular tee on the return. It will probably work but may add more restriction to the system.

    There is nothing wrong with a combination system. You could have a two pipe system with some radiation that is hooked up with venture tees...nothing wrong with it if piped right.

    By right, I mean right pipe sizes and piping configuration.

    the only way to figure it out is draw every pipe, mark out pipes sizes and show venture tee locations clearly. Then we can see what is going on. draw boiler and pumps and zone valves if any
  • SuperTech
    SuperTech Member Posts: 2,206
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    Thanks for taking the time to respond Ed. On my sketch I marked the location of the Venturi tees with an M for monoflo. The are all on the 1" supply pipe. The supply and return pipes are all 1" with the exception of the main supply coming off the boiler, that is 1-1/4" and is run straight across the length of the house, with the Y in the middle. All cast iron baseboards and fin tube convectors are connected by 1/2" branches. No zone valves. Single 007 mounted on the return unfortunately.

    I spent a lot of time last night reading heating history on here, including install manuals for the cast iron baseboards. It helps clear things up a little, but also raises some questions.

    One manufacturer recommended that with 1" mains that all branches should be 3/4". And I haven't done the math yet but it seems based on what is there that a 007 may be insufficient.

    I still am wondering why the one corner in the living room doesn't have any piping below it. This is the only corner with an inverted corner for what it's worth.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,835
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    Interesting set up , it looks like it was over engineered to distribute ... it could have be simplified with an single mono flow loop .. How does it work , how did he do ?

    There was an error rendering this rich post.

  • SuperTech
    SuperTech Member Posts: 2,206
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    It performs great heating the main floor. The downstairs bedroom doesn't heat well enough, likely due to the fin tube convectors being used versus the 90% cast iron emmiters in the rest of the house.

    The system definitely wasn't installed in a manner to keep material and labor costs minimum, but it's not completely by the book either
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,847
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    One thing about water systems is compared to steam water can be screwed up pretty bad and still work
    Solid_Fuel_Man
  • SuperTech
    SuperTech Member Posts: 2,206
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    After the winter is over I want to try to improve the piping of the system. Install either a couple of diverter tees and heat emmiters in the room downstairs or just make it a separate zone. I want more cast iron baseboards but they are expensive! I'd like get rid of the fin tube convectors in kitchen as well.

    The only thing is I don't see many diverter tee systems to know what a perfect installation should look like. I'm going off of the manuals from the 50's to learn about the details. I'm not sure exactly what the manufacturer of mine is. Looks like Base Ray or Crane possibly?
  • Big Ed_4
    Big Ed_4 Member Posts: 2,835
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    Baseboard I feel are not the best emitters by design ... They take up too much wall space in the real world ... Places better off for furniture. Radiators under the windows makes better sense .. Cast is too heavy for me now a days , newer modern panel radiators , I feel is an far better choice ..

    There was an error rendering this rich post.

  • SuperTech
    SuperTech Member Posts: 2,206
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    I haven't considered panel rads. I like the way the cast iron emmiters hold the heat. I definitely think panel rads are a better option than fin tube. But for my house I'll take the heavy, bulky cast iron baseboards.