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Two Pipe Direct Return with TRV's

Flo
Flo Member Posts: 14
I just ran a 3/4" direct return loop for 5 radiators on the first floor of my parent's house and a 3/4" direct return loop for 4 radiators for the second floor. I branched off with 1/2' pipe to the supply and return each radiator. I hod a plumber come by, and he mentioned that i made a big mistake by branching off with 1/2" pipe and should have used 3/4" pipe instead. He said it might be ok for the first floor since the radiators are very close, but for the second floor, where the radiators are 15 to 30 feet away from the loop, there will be a lot of heat loss and 1/2" won't cut it.

Also, he mentioned that i should have ran the radiator in series, which i did not want to do to being with, since i from what i read, the temperature drops by the time the water gets to the last radiator.

He mentioned that the loop i currently ran would not work (two pipe direct return).

I did not install any balancing valves on the system, and i would not know how to balance the system.

My question are....Should I change the 1/2" pipe that runs to each radiator to 3/4"? The radiators vary in size, the biggest one being 10000BTU.

Should i modify the loops to two pipe reverse return so that i don't have balancing issues? Or will the thermostatic valves on the radiators solve the balancing issues?

Comments

  • Flo
    Flo Member Posts: 14
    Balancing Two Pipe DIrect Return

    I did a little more research and installed the design software from Taco. It shows the flow rate after each radiator, but i'm not sure if that's the actual flow rate or the optimal flow rate. I'm guessing that i should install 3/4"  balancing valves on the supply  pipe after each  radiator's 1/2"  branch and adjust the flow rate to match to the design? Will that guarantee the water will flow through the 1/2 branched loops?



    Other designs that i have seen show that the balancing valves should be installed on the return from each radiator. I understand that it would optimize the flow for each radiator on the return side, but if i don't install them on the supply pipe as well, i have a feeling the water will avoid the 1/2" branches and get no water in the radiators.



    I'm a little confused, so i would appreciate it if someone can clarify all this for me.



    By the way, I will be using a QuietSide DPW 120A boiler with these loops.



    Thanks in advance for you feedback.
  • Flo
    Flo Member Posts: 14
    Balancing with lockshield valves

    I found my own answer. The balancing is done at each radiator with the lockshield valves on the return side.



    So not that i got that covered. My last question still remains if my 1/2" branches off of the 3/4" loop with work right.



    I read a post on this forum that normally the supply is progressively reduced and the return increased.



    Will my loop work properly?
  • bob_46
    bob_46 Member Posts: 813
    info

    Flo, we need more info, total load,load on each loop, load on each branch in btuh. A one line diagram of how you piped it. If you have a trv on each radiator you don't nave to worry about balance.
    bob
  • Flo
    Flo Member Posts: 14
    More info

    The load on each loop is 26500 and 24000. Total load is 50500. Load on branches varies. First branch is 1500BTU( towel warmer) second 3500, third 3500, fourth 8000 and last 10000.Branches on the first loop only extend 6 to 12 inches from loop.



    Second loop first branch 8000, second 2500, third 3500 and last 10000. branches on the second floor extend furthest away from the loop. First branch 30 feet, second branch 15 feet, third branch 15 feet last branch 25 feet.



    All branches are in 1/2 copper, while loops are in 3/4 copper.



    I will take a picture of my schematic later and post it on here. Thanks again.
  • Flo
    Flo Member Posts: 14
    Schematic Picture

    Please see attached picture schematic.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Need a better picture....

    Do this. On your PC keyboard, there is a button called Print Screen (Prnt Scrn). With the screen you want to share, up and running, hit SHIFT, PRNT SCRN. This takes the current screen shot and saves it to your PC's internal memory.



    Bring up MicroSoft Paint.



    Click on EDIT, then click on PASTE and the screen shot you took will appear. Crop it to the part you want to share, and save that down as a JPEG format picture to the file of your choice.



    You can now share a much better copy of your screen shot with your fellow Wallies with older flailing eyes...



    Thanks



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • bob_46
    bob_46 Member Posts: 813
    pipe

    Flo, your pipe sizing and layout looks fine. I don't know what all the little black things are all over the piping, valves maybe? You only need a trv on each radiator and a few ball valves to make purging easier. You could also add a ball valve at each radiator for isolation. Your near boiler piping needs to be revised. You will also need a pressure operated by-pass or one of the new Grundfos smart pumps.
    bob
  • Flo
    Flo Member Posts: 14
    Better Pic

    Those dots are balancing valves that i was going to add. Since the TRV's will take care of the balancing, I am not putting them in anymore. I am still going to add one on the supply and one on the return where the two loops branch off from the boiler.



    So, even though i branched off with 1/2 pipe off the 3/4 loops, i should not have a problem getting water to the radiators? Even the ones on the second floor which are an average of 20 feet away from the loop? That would be great news, as i really didn't want to remove all that 1/2 pipe to replace with 3/4.
  • Flo
    Flo Member Posts: 14
    Presure regulated bypass

    Bob, just wondering what the pressure regulated bypass will is bypassing and what the smart pump does?
  • Greg Maxwell
    Greg Maxwell Member Posts: 212
    Rads

    It looks like you have a 2 pipe reverse return there, with the first rad to supply, is the last to return. I believe your piping is correct. I dont however understand why you are going to do all this, and not zone the floors seperately, and create better control. And, you will have some fun purging all this. But that all said, I believe your basic theory is sound.
  • bob_46
    bob_46 Member Posts: 813
    piping

    Flo, I am not familiar with your boiler, I looked it up on line and to me it looks kind of Mickey Mouse but then I am old school. Your piping diagram is definitely WRONG for this boiler it has to be piped PRIMARY/SECONDARY you cannot use the pump in the boiler to circulate the system. I recommend that you read Dan's books Pumping Away and primary secondary piping before you get in any deeper.
    bob
  • Flo
    Flo Member Posts: 14
    Boiler

    Thanks for the input. I did pipe the boiler Primary/Secondary and added a circulator pump. Just wondering why the internal pump can't be used?

    Greg, I ran two separate loops just in case we decide to put in a separate boiler for the second floor. It's a two family house.
  • bob_46
    bob_46 Member Posts: 813
    pump

    The pump that comes with that boiler is not strong enough to circulate the boiler and the system. You have to pipe primary secondary so that the flow through the boiler is constant even as the flow in the system changes with the operation of the trv's. By the way the pump in the photo is installed wrong the shaft HAS to be horizontal.
    bob
  • Flo
    Flo Member Posts: 14
    Pump

    Bob, are you saying I should put the pump on veritcal pipe or that it looks like the pump is pointing downwards?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    What he's saying is...

    You can't mount that particular pump the way you have it. THe thrust bearing was not made for the motor shaft to be placed vertically, like it is. You need to turn it 90 degrees so the face of the pump is vertical, not horizontal.



    Will it work the way its installed? Yeah, for about a year...



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Flo
    Flo Member Posts: 14
    Pump

    I see what you're saying. So If I rotate the pump 90 degrees, I should be fine.
This discussion has been closed.