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Re-routing Heating Loops

mpdb2mpdb2 Member Posts: 24
I have two heating loops running through my house beam. One loop serves the first floor zone, the other the second floor zone. Mono flow tees serve radiators off each loop. The pipes are in the way because I need to reinforce the house beam. My plan is to use 45 degree elbows, not 90s, to raise both loops approx. 12 inches above the beam . All of the mono flow tees will remain at the original (lower) elevation, none will be in the raised areas. Attached is a photo showing where the loops run through the house beam.

Here are my questions:

Are there any concerns with running the loops above the beam, then back down? - does this have the potential to trap air?

Are there rules of thumb for how far I need to keep the elbows away from the mono flow tees?


Comments

  • JUGHNEJUGHNE Member Posts: 6,896
    Are you going to replace the beam or just sister/reinforce it?
  • Jamie HallJamie Hall Member Posts: 12,847
    I might ask also... why do you need to reinforce the beam? The location of the holes for the pipes is not reducing its strength materially, nor its stiffness.

    Before you just slap some reinforcement on there, consider: that is a main support beam for the structure, and if there is a problem with a failure somewhere, you must determine why and choose the correct reinforcement. If there is a problem with inadequate stiffness, you should be aware that reinforcing to improve stiffness (reduce deflection under load) is problematic, at best. If you need to reinforce the beam because you plan to add load to the structure, that can be problematic as well.

    In fact... unless you yourself are a structural engineer, qualified to design wood structures, you may need to find one.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • GroundUpGroundUp Member Posts: 970
    To answer the question, no I would not be concerned about an air trap or vents if you have vents at your rads. This is assuming the rest of the system is piped properly and you do not have frequent makeup water. As for the distance to the monoflo, I like to keep them 12" minimum from an elbow but have seen them within an inch and haven't seen any issues to date, but not saying it's proper. With that said, I too am wondering about the beam reinforcement.
    Zman
  • mpdb2mpdb2 Member Posts: 24
    The beam is deflecting at another span and I will be beefing up the entire length of the beam by sistering LVL on each side. The heating loops need to come out to install LVLs anyway, so getting a little extra headroom in this area would be helpful.
    Zman
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,041
    @mpdb2

    I would keep the monoflows 12" from the elbows if possible but it's not super critical. I would put a coin vent on the top where you cross over the beam just before the 45 that drops down to the original elevation. You could trap air there
  • Jamie HallJamie Hall Member Posts: 12,847
    Not to be unduly blunt -- but this is a major structural modification. I do hope that you are thoroughly familiar with fastening and supporting techniques which will be involved; for all I know, you are. However, please keep in mind that all the relevant parameters for the LVL -- particularly Fv, Fb, Fh, and modulus of elasticity -- will be very different from the original wood, and the distribution of load between the sisters and the original will be difficult to predict. Correct fastening will be essential, as will appropriate modifications of the beam seats at the ends and, if it is continuous over intermediate supports, at the intermediate supports.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • hot_rodhot_rod Member Posts: 13,313
    I had to stiffen a beam in a barn remodel I did years back. An engineer friend gave me a good idea. Instead of beefing up the double 2X 8 beam to a required double 2 X 12 I installed a piece of 1/8 X6" wide steel between the 2-2X8 and bolted every 24".
    It made a huge difference and I didn't have to give up the 4" of headroom. The steel needs to be pinched between the joists to prevent deflection.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    Zman
  • Jamie HallJamie Hall Member Posts: 12,847
    That's one of the very best ways to handle the problem, @hot_rod -- but one does need to have that double sandwich to keep the steel from buckling.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ZmanZman Member Posts: 5,827
    hot_rod said:

    I had to stiffen a beam in a barn remodel I did years back. An engineer friend gave me a good idea. Instead of beefing up the double 2X 8 beam to a required double 2 X 12 I installed a piece of 1/8 X6" wide steel between the 2-2X8 and bolted every 24".
    It made a huge difference and I didn't have to give up the 4" of headroom. The steel needs to be pinched between the joists to prevent deflection.

    Yes, This works very well, especially when you have hieght limitations with wood beams. "Steel, strong stuff".
    It is easier than you think to install. You just order the plate steel precut and punched from the supplier. Once you have some buddies help get it in place, it is just a matter of drilling from both sides and through bolting the "sandwich".
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • mpdb2mpdb2 Member Posts: 24
    Yes, I’m familiar with laminating beams together. The original beam hasn’t failed, but is tired after 100 years of work. A mid-span sag is noticeable if you look for it. The original beam has plenty of bearing on it’s own as it is a solid piece of wood. Thanks for the concerns. BTW, the beam with the steel plate in between two pieces of lumber is called a flitch beam.

    Back to my heating line question, it looks like I only have one suggestion for an air vent, but I would have thought it would be better where the lines first rise up to the higher elevation, not at the other end just before they come down. ???
  • Jamie HallJamie Hall Member Posts: 12,847
    I'm glad you know what you are doing. I have seen some rather spectacular failures in older timber structures resulting from not fully analysing where the stresses are after they have adjusted, and attempts being made to lift or straighten beams...

    And I might point out: wood does not get "tired". Metals do, if under reversing loads beyond a certain stress level. Wood does not. It will often -- I dare say usually -- adjust itself to manage the imposed loads, but once it has it will stay there -- barring rot or other actual damage -- for centuries.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • mpdb2mpdb2 Member Posts: 24
    Yes Jamie Hall, you are correct. Using “tired” as a description was not the best choice. My point was that a 100+ year old beam is entitled to “show its age” and sag a little. I agree, jacking would be the absolute wrong approach. Reinforcing in-place is one way to go with these situation, which is the approach I’m taking. Another is to add columns, which I’m trying to avoid. Unless, of course, there is absolute failure, then you have a completely different kind of mess on your hands.

    As an aside, when analyzing the loads on the beam, it is probably close to 25% over stressed. My conservative analysis approach of under guesstimating the Fb and over estimating loads is closer to 50%. The LVLs almost double to load bearing capacity. The original beam is 8x8, so not much depth to provide adequate bending stress resistance. (Fv is not an issue here).
  • ZmanZman Member Posts: 5,827
    I sure wouldn't hurt to cut in a tee where you can install either an air vent of a coin vent. I have found that remote air vents like that tend to get forgotten about, until they leak. I would be surprised if air gets trapped in a little elevated area like that but stranger things have happened.
    If that pipe is getting steady flow (not an imbalanced loop of the main) and the circulator is "pumping away" from the PONPC, I think you will have no air issues.
    Sorry this post took a turn into the structural world and I hope this answers the "heating help" question.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    SuperTech
  • Jamie HallJamie Hall Member Posts: 12,847
    Try and figure out what the original wood in that beam is, @mpdb2 . Some of the older hardwoods have astonishingly high values for the relevant stresses -- the Timber Construction Manual has a useful table for them (I've run into situations in some 18th century structures with Fb up around 6,000 psi). You may not be as overloaded as you think you are!
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    Zman
  • mpdb2mpdb2 Member Posts: 24
    Zman: it is “pumping away” I took care of that last summer. See my posts to the forum over the last couple of years and attached photo of final installation:

    https://forum.heatinghelp.com/discussion/166700/pump-locations-when-adding-a-low-loss-header#latest

    https://forum.heatinghelp.com/discussion/170765/pumping-away-question#latest




    I’m thinking of rolling the dice and not installing the air vents as the majority consensus is that trapping air would not be an issue and I’d rather not have another maintenance point that will be forgotten anyway. I’m planning a dropped ceiling under these pipes, so it’s not something that I will be seeing regularly and remembering to check - out of sight, out of mind.

    Jamie Hall: adding the LVLs is not that difficult, heating loop relocation aside, so I’d rather err on the side of assuming the beam is undersized, or has a lower structural capacity. The former owner added a partition that I’m now suspicious was also to add a support stud or two. See double stud under the beam on left side of attached photo.




    You gotta love these discussions, you never know where they will take you.
  • JUGHNEJUGHNE Member Posts: 6,896
    In my house I had to take S & R up and over then down to a radiant manifold. In my fear of air trapped in the high point I installed 3/4 x 1/2 tees. Then because this would end up with duct work hanging under it, 1/4" copper tubing was run to an accessible location. I put ACR schrader fittings on the end.

    There was a fair amount of air to bleed on initial start up, but I have forgot about them after 20 years until this posting.
  • Jamie HallJamie Hall Member Posts: 12,847
    Love the columns! Cedric's home -- one of several I look after -- has a few steel "lolly" columns doing just that... the old timers didn't always get it right.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,041
    @mpdb2

    Weather you need an air vent is determined by the water flow. If the velocity is high enough the air will be carried out of the high spot and vented else where. If it's not high enough you could have difficulty.

    Your choice is yours.
    Depends on the pipe size and the amount of flow.

    The old axiom drain the low points vent the high points still applies
  • mpdb2mpdb2 Member Posts: 24
    The loops are one inch with 1/2 inch feeds to cast iron radiators. The pump runs around 4gpm in cool weather and up to 6 or 8gpm when it gets really cold in the teens or lower.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,041
    With 1" @4gpm that is about 1/2 the pipes flow capacity. You would trap air at that flow rate
  • hot_rodhot_rod Member Posts: 13,313
    Pretty much every ceiling mounted unit heater and attic mounted AH presents a high point, it cannot be avoided. Usually those installation will have bleeder ports and in some cases need auto-air vents. Some AH manufacturers add a bleeder on the coil headers.

    When the system is off in summer season, any air not eliminated will find its way to the high points. So first season start up is the critical time.

    A good micro bubble type air purger will minimize the potential for air locks, as will adequate flow conditions.

    Variable speed/ flow does add another challenge for getting and keeping air at bay :) flow velocity bellow 2 fps tends to leave air behind.

    Manual vents are inexpensive and reliable, allowing easy start up, IF you do get air trapped in high points. If it happens over and over, add an auto vent.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • EdTheHeaterManEdTheHeaterMan Member Posts: 572
    edited July 4
    @mpdb2 said "Back to my heating line question, it looks like I only have one suggestion for an air vent, but I would have thought it would be better where the lines first rise up to the higher elevation, not at the other end just before they come down. ???"




    You have to imagine in your mind's eye what the water is going to do. The circulator pump is going to add some flow or movement to the water. If the air vent is at the entrance end of the high point, then we need to wait for the water to flow backward from the end where the water is going, to let all the air out. The pump will be pushing the water against the direction you want the air to get to. (as in the middle illustration.)

    The top illustration is pushing the air in the same direction as the water. So the pump is helping the air get to the vent.

    Finally, the bottom illustration shows a way to install a manually operated vent with access from below the ceiling. If you have a problem getting the air pocket to move down to a purge valve, this purge vent idea will be there if you need it.



    Place a decorative dome over the valve in the ceiling so it looks like a smoke detector, video camera, or motion detector from the alarm system. It will look like it belongs there and you won't even notice it after a while

    SuperTech
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