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Diverter Tees design

Wayco Wayne_2
Wayco Wayne_2 Member Posts: 2,479
in THE MAIN WALL
asked for ideas on piping a barn for panel rads. Now the customer wants to use used cast iron rads that he found on a job. Now I'm thinking just ring around the whole barn and cut in diverter teesIt's about 200 ft around the perimeter and I'm expecting 12 radiators. I started rule of thumbing it but then decided to double check. 1 inch M is borderline. The heat loss of the structure is 65,000. According to Siggys piping software I can get a flow of 6.4 with the high speed of a Grundfor 15-58. Should I go up a size. I would only need it on very cold days when all of the rads are calling. 6.4 GPM is only 1/10 of a GPM low based on a 20 delta tee, but I hate to be caught short if there is a need to upgrade capacity. My background is duct work so I'm nervous about this. I have limited experience in design piping. Any help or feedback is appreciated. WW

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Comments

  • Uni R
    Uni R Member Posts: 663
    Diverter Tees

    Wayne, if you are thinking of using a single pipe design with diverter tees you will either have to have continuous flow through all of the rads and size them perfectly or build special bypasses for them if you need to close the flow to any of the rads. If you close off a rad on a diverter tee everything is forced through the diverter and you'll end up with very restricted flow. They flow well only when everything is unrestricted. This is why manifold and reverse return layouts are best for this application. Then you have more freedom to use TRVs.
  • Neil_5
    Neil_5 Member Posts: 179
    Uni R

    I have an system built on the mono flow T in 1955, and all the convectors habe a valve that can turn 45 deg to turn off/on. You above most mention the fact that the systems works better with all the radiator in open position? Any reason why these valves were installed?

    Trying to undertand whats the best menthod to run my system.

    Thanks,
    Neil
  • Uni R
    Uni R Member Posts: 663
    Balance

    Neil, they can be used to balance the system. You can fine tune it with the valves. You can close off a rad or two and nothing drastic should happen, but it does make your circulator work harder. It's cumulative/ I've had a basement branch capped the past few years while doing renos so all of the water is forced through a couple of diverter tees. If however I put TRVs on 80% of my rads and they were all closed, there would be so little flow going through the main the water wouldn't likely have enough flow to be diverted into the branches where heat is required.


    To balance your system, start with them all open. If any room is too warm, then you want to partially close the valve until it is balanced. Do it a little bit at a time. If one room is too cold, make sure it is not an airlock or an obstructed rad. If you can reduce the heatloss in that room that would be the next thing to do. If it's still too cold, then you have to get creative.
  • Neil_5
    Neil_5 Member Posts: 179
    Thanks

    thanks for the explanation.

    neil
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Wayno..

    are the mains above or below the convectors? I can tell you that a 1558 ain't gonna cut it if the mains are above teh radiators. How water simply don't like to flow down hill, an dcold water don't like to flow up.

    It's the difference between needing two diverter tees per rad (if above) versus just on one the radiator outlet (if below).

    ME
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Hey Mark.

    The rads are all above the main pipe. I was thinking of running 1-1/4 around the bottom perimeter of the first floor and feeding both the 1st and second floor using one diverter tee per rad. All 12 CI rads will have TRV's. I know to size for temp drop towards the end of the run. I don't know about a pressure drop. Heat Loss is 65,000, so GPM at delta of 20 is 6.5. The B&G catalog says a cv of 24 with side branch plugged on 1-1/4 diverter tee. That doesnt sound like much of a pressure drop to me. Doesnt that mean I can pass 24 gpm's through it and get only 1 psi pressure drop. How do I do the math for a 400 foot run with 12 diverter tees? I'm about to dig out my old IBR manual from 15 years ago to figure it out that way. I wish Siggys software had diverter tee circuits on it. Thanks for any help you can through my way. WW

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  • ScottMP
    ScottMP Member Posts: 5,883
    Wayne

    We did the same thing for the second floor of a home and used TRV's. No problem using monoflow tee's. I'll try and go back and look what the combined load is but we used all cast iron rads ( brand new ) and its very comfortable.

    As I remember, we split the load and used 3/4". I think the idea is that with TRV's they are hardly ever fully closed. They they tend to modulate between fully open and fully closed.

    Scott

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  • Drew_5
    Drew_5 Member Posts: 11
    What is a TRV?

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Thermostatic Radiator Valve

    They're a non-electric proportional flow "thermostat" for radiators. They offer very tight temperature control and each space can be kept at its own temperature without any zone valves, added circulators, etc. They work with all boilers but are ideally suited to those that modulate.

    While best suited to two-pipe systems, they can be used in one-pipe systems with careful design and understanding of the limitations.
  • Uni R
    Uni R Member Posts: 663
    A 15-58 will do it

    Mark, I am using a 15-58 (with the flow check removed) on a black iron 1.25" diverter tee setup. There are I believe 13 branches above the mains (about 90' of fintube on 2 upper levels) and 3 (8' of 18' of fintube) branches below the mains with diverters on each side. It's a backsplit so the mains follow the basement and then drop 4' for the upper 2 levels into a heated tall crawlspace. One of the lower branches (10') is capped for basement renovations.


    The 15-58 runs perfectly on the middle speed. Once the downstairs is complete, I won't be surprised if I can run it on the lowest speed. This 15-58 replaced a B&G 100 and at the middle speed running 200 days continuous a year will pay itself off in only 2 seasons through electricity savings. The home heatloss is in the same range as what is being proposed here. It's around 70,000 and fired by an old boiler at 0.65 gph with outdoor reset.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Thanks for the input Scott

    Pictures look great. I'll send the customer here to visualize. Did you use a PDBV on the circ. or would that be guiding the Lily? WW

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  • ScottMP
    ScottMP Member Posts: 5,883
    Wayne

    I think you mean " Gilding the Lily " , it refers to putting gold on a beautifull lily.

    Back to heating :). We used a P/S set up which I hope eliminated the need for a PDV. The system is also run off a Tekmar 363 and shuts down on WWSD.

    Scott

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