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flow velocity and pipe size.

keyote
keyote Member Posts: 659
Planning my near boiler piping and i tend to like to overbuild but am unsure if in this case its just a little more expensive or bad design issue.
I have a Triangle tube 110 with a smart 50 indirect, and four radiant manifolds one in the basement with boiler and three on three floors above. Each floor is almost identical basically 1150 sf with four loops on a 1" manifold plan to put zone valves on the s/r risers to manifolds.
Did my heat loss in loop cad and got the following.
Top floor 3.6 gpm /10.7 hd I used a 1" copper s/r riser because i plan to add a couple loops from it to a roof addition one day.
2 flr 3.2 gpm/ 13.8 hd thinking 3/4" s/r would do
ground floor is 2.2 gpm/ 12.2 hd think 3/4 s/r riser
basement is 2.6 gpm /15.7 hd [long loops in slab] 3/4 s/r

BTU loads start at about 16.5 k top flr down to 9 k basement. total 52 kbtu [plus dhw] total head 15.7 [ right its the highest zones head only] ? total 4 zones flow 11.6 gpm, pressure is 28' x .5 =14 plus 5 = 19psi [if i add that PH addition it will go to 25 psi but still under tt110 s 30 psi prv. water temp is 112- 124 plan to put actuators on each loop so think i can just keep 124 temp and the slabs that want cooler water can just be turned off when met.

So assuming the s/r riser sizes are ok i was trying to size the near boiler pipes. For the DHW ill go with the 1-1/4 taps on the smart tank, but the feed from the boiler to to the manifold risers is what im not sure of.
I think at 11.6 total gpm flow 1- 1/4" copper gives .92 fps and 1" gives 4.73 fps siggy says keep it btwn 2 and 4 fps .

To make it interesting im not sure if i am going primary/ secondary or straight through. i want to be extremely efficient and would like to replace the internal pump with an alpha and run straight through. Some guys i read on here say the pressure drop of the tt110 allows this in many instances and Im hoping my fairly low flows, heads and balanced zones is one of those instances but cant find how to verify this or quite understand how this works with the boilers min flow requirements.
So it might be a question of sizing a straight through pipe configuration or primary and secondary pipe sizes. If that matters
I actually dont know wtf im doing but im determined. LOL Im guessing non P/S configuration and one pump might benefit from a undersized pipe to keep pressure higher and P/S it wont matter so much dividing the load.

Anyway if my velocity calculations are correct i seem to be between pipe sizes how serious is this turbulence wearing pipes and will i get the air out. Thanks guys the tinkocker

Comments

  • MikeSpeed6030
    MikeSpeed6030 Member Posts: 69
    edited July 2016
    Double check your flow velocity calcs. I wonder about the difference between 1.25" and 1". But anything close to 4 fps will cause excessive flow noise, not necessarily pipe erosion. Doesn't necessarily affect air removal.
  • Gordy
    Gordy Member Posts: 9,514
    edited July 2016
    2-4 fps. To low, and air removal is hindered. To high velocity noise, and pipe erosion can happen.

    Size pipe for btu max load. Everything goes hand in hand.

    1" = 72k
    1 1/4" = 125k
    SWEISteve Minnich
  • Gordy
    Gordy Member Posts: 9,514
    In a nut shell use 1"
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,217
    Pipe your near boiler piping in such a way that it enhances air removal naturally.

    Also, your total head vs gpm is not quite the way I would like to see it. I would look over the plans and see if you have any extra long loops. I will usually shoot for 250' when using 1/2" pex.

    GordyPaul S_3
  • Gordy
    Gordy Member Posts: 9,514
    Harvey is right the head losses do seem to be high for the flow rates.
  • keyote
    keyote Member Posts: 659
    I have a post up " is this good near boiler piping" from last week. I put up pdfs from the cadloop program i did my heat loss and lay out in, for each floor it has all the calculations as well as loop layout. There really were not many really long loops but a few almost 300 I actually shortened a couple when i realized they were raising head. Could it be you guys dont do multistory buildings? well i would love it if someone would take a look a few guys commented on the near boiler stuff but not on the loop,riser, manifold, design Its worth mentioning those calcs i used 1' risers to all floors not just top floor. Unfortunately the way the pdf loaded you have to open it up after saving it it think
  • keyote
    keyote Member Posts: 659
    Gordy that would mean with only 52kbtu i would have a 3/4" primary secondary to feed four manifolds? or just step it up a bit and go with 1'? would that be ok with the DHW at the 1 1/4" ports on tank?
  • Gordy
    Gordy Member Posts: 9,514
    System elevation has no affect on circulator size, piping size etc. the only difference is system pressure. System pressure is what gets the water to the top of the system.

    It would help if you keep everything in one thread.

    No 3/4" pipe is only good for 42k at the recommended fps.
  • keyote
    keyote Member Posts: 659
    I have re posted the loop cad design views for each floor below.
  • Gordy
    Gordy Member Posts: 9,514
    Usually when designing loops you try to keep loop lengths +\- 10% of each other. However with manifolds that allow circuit adjustment with flow indicators it becomes less of an issue. Until it comes to the circulator sizing.

    It seems that your longest loops by chance cover the higher load areas. So in trying to keep a delta of 10* your head goes up quite a bit as you will notice because of the longer circuit length.

    So look at your circuits that require lower flow rates do to lower loads, and try to see if you can burden the lower load areas with longer circuits, and get the higher load circuits shorter. This will get your head loss down, and keep you in ECM territory.

    Maybe rethink manifold locations. Seems you are trying to cover each floor with one manifold. Maybe some extra manifolds. Your highest portion of head loss will be the tubing not the delivery to the manifold so long as pipe size is correct.
  • SWEI
    SWEI Member Posts: 7,356
    Don't forget that a 1/2" x 1/2" x 1/2" tee also constitutes a manifold from a design perspective. Split the long loop in half and place the tees properly (think mini reverse return) and you don't even need balancing valves.
    Gordy
  • Gordy
    Gordy Member Posts: 9,514
    Good point, and a money saver Kurt. I should have worded that differently as to even larger manifolds for more circuits. The program should at least have warning pop ups letting the user know of high head loss, and or circuit lengths.
  • SWEI
    SWEI Member Posts: 7,356
    I keep hoping for some small manifold options to appear in the market. Two- and three-port stainless or brass manifolds with all the accessories add up fast, and supplying them with 1/2" or even 3/4" PEX involves even more adapters.
    Gordy
  • hot_rod
    hot_rod Member Posts: 14,836
    Copper manifolds are readily available in any configuration you want. Anything from basic copper stub outs to valves and balancing options. Dahl mini ball valves are commonly used, or add your own valve or adapter.

    I would buy the 24 branch Custom Cuts and just lop off the number of branches the job required.

    Some versions come with swaged ends to couple the short left overs.

    Or buy a T-drill and make your own from brass, copper, steel, or SS.

    I have even used the steel manifolds that are available for CSST manifolding.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SWEI
    SWEI Member Posts: 7,356
    I've used those (from Sioux Chief) but the header size is still a bit on the large side for a 2.5 GPM zone. To get the config we want (3/8" F1960 barbs with balancing valves) I have to order 25 pieces -- and that's before we start cutting them down.
  • keyote
    keyote Member Posts: 659
    Thanks guys sorry i didnt get back thought the thread died so i was installing the indirect at least.
    I have ten days left on the cad loop so I will open it up and see if i can implement your ideas. The top floor is already built and occupied by tenants so that sin stone. I actually did already shorten some loops when i realized they had given me high head, but I ended up then having rooms with overlapping loops which worked ok on the large ground floor parlor But part of why i did what i did is i basically gave each major room or bed w bath its own loop so i intended to put an actuator and thermostat for each room/loop. my use and occupancy varies a lot so another reason for micro zoning, another consideration was nailing t and g hardwood over loops gets tricky when the S/R are running parallel and its an historic house which also has constraints. I know some of the manifolds you can buy additional sections s i imagine you can make what you want. true i was keeping the risers running straight up from boiler to center of building I figured if any pipe had to cross the building laterally it ought to be in a floor panel.
    So another thing I was aiming for was starting with the already built top floor trying to balance the rest of the loops on lower floor to that as far as delta t and water temp and most importantly floor temp because mostly wooden floors.What happened was the floors that got too hot were the kitchen and baths where i have tile over cement board. I actually thought i had low head and flow and fairly uniform . so what would i be looking to get in other words my first priority was floor temp and delt t 10 then i tried to keep the loops under 300. are there better ways to prioritize and ideal flows and heads to aim for are you saying even with actuators my heads are too high for an ecm and i think you are thinking an ecm per riser or one ecm secondary and zone valves. My latest idea is a buffer tank i got a brand new smart 50 for a song and a used smart 30 or 40? with the boiler which im thinking i could use the smaller as a buffer with solar eventually but with microzones and erratic occupancy and low water temp it might be a good ide though maybe not the ideal tank for it but its basically free and not doing anything else