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Tips for quieting down a staple up radiant floor?

MTCMTC Member Posts: 182
I have radiant floors in my house, stapled up with stamped aluminum transfer plates. The system works well, heats well, etc, but makes a little more tube movement noise on start and stop of circs than I'd like.

It is an open combined DHW system (please, not the place to argue about this system, go to this thread if you must say your piece about my open combined system... <a href=""></a>). B/C of this, I keep water temps at 150F, which adds to the expansion/contraction, but I"m not comfortable reducing the temp much with it being a combined system. Also, correct me if I'm wrong, but this system would make an ODR type setup difficult/impossible? Continuous circ would be great and probably solve the problem, but not a short term feasible option. Maybe down the road I'll put in smart circs and try to vary circ speed to achieve this effect, but for now, not an option.

Speaking of circs, they're 3 speed GrundFos circs. I have them set at medium speed, should I turn them down so the system has to pump longer to meet thermostat? They need to be at medium in the coldest part of winter to meet load, but most of the year probably could be set lower.

I have access to 1st floor tubing, and have already gone through the whole floor, removing some talons on the loop ends so that it can move more freely, a few plates that were a bit too close to the loop ends, etc. Also, the drilled holes had no sleeves or anything through them, so I did the "milk jug" trick, cutting up strips of milk jug plastic and wrapping the tubes through the holes.

This was on a 60ish degree day, after a week of warm days, so the floor was sitting right about at 60-65 degree water temp. I turned up the water tank to 160, and when it reached temp, turned on the floor. This was a 100 degree temp change, so lots of pipe movement to be expected. I can def still hear it, but its been greatly reduced. For comparison, I ran 2nd floor under same conditions, and it was substantially noisier than 1st floor.

Ok, sorry for being longwinded. I am going to have a short window of access to the 2nd floor tubing soon during a remodeling project, and was planning on doing all the above steps again to 2nd floor. I'm just wondering if there's anything else I should be doing to further help the cause while I have this small window of access? Any suggestions?

Thanks everyone. Love the wall!


  • Jamie HallJamie Hall Member Posts: 14,910
    OK, I won't

    say anything about open combined systems.

    Your tube noise is probably coming almost entirely from expansion and contraction, and the efforts you have taken so far to limit the noise with the milk jug trick and avoiding anchoring the ends and the like are very very good steps in the right direction.


    What you really want to do is to eliminate that expansion and contraction -- which means holding the tube temperature as close to constant as you possibly can.  This is, in fact, a very good sort of application for outdoor reset!  The objective of the exercise, using the reset and some valving and bypassing, is to have the floor at all times at the temperature needed to satisfy your losses -- and never turn the circulation off.  Vary the water temperature circulating in the floor to match the loss as closely as possible, changing it as slowly as possible (using a long averaging for the reset -- which you can do if the whole floor system is fairly high mass).

    What your reset will do is modulate a mixing valve to get the water temperature desired in the floor to match the heat loss.

    I haven't really worked this through, but that's the concept.  I might add that I don't think it will help your overall efficiency much...
    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: 6,336

    The route of the problem is rapid thermal expansion. The quick increase of almost 100 degrees is too much.

    Reducing water temps and going with outdoor reset would help greatly. As you know that's not a great idea with an open system.

    I think you are either going to have to add a mixing assembly and close the system or live with the noise. You simply can't stop the expansion.

    It is really interesting to me, the passion people have for their open systems. Almost like a religion...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Rich_49Rich_49 Member Posts: 2,553

    an outdoor reset mixing valve for the radiant portion of the system only . If at all possible change those circs out for a Delta T circ like a Bumble Bee .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • MTCMTC Member Posts: 182
    Thanks guys,

    for the input so far. Glad to hear I'm on at least some of the right tracks...

    As far as the 100 degree change, that was a sort of extreme example meant to test the changes I've made. I don't think in real life operation it ever has that big of a shock. Maybe the very first run of the season it would be somewhat close to that, or after a long warm spell and then sudden temp drop, but generally it wouldn't be that large of a change. I just wanted to be SURE to hear movement, so set up an extreme test.

    Yeah, the Delta T circs was what I was kind of getting at earlier, but not sure I want to go that far yet. The system isn't that old and is working well. I'll certainly be thinking about a smart circ of some sort like the bumble bee when the time comes to swap them out, but in the meantime just trying to do whatever I can to reduce the noise.

    Can someone give me a simple explanation of how an ODR/mixing valve would work on the radiant portion of the system only, w/o converting it to closed system? I've only used them on potable water systems before. The valve basically just adds cold water to the incoming hot water from heat source, in my case after the hot fixtures branches off, correct? Does it remove hot water to displace the needed volume for the new incoming water? Or is the mixing valve using a bypass from the return as the mixing water instead? That might make some sense... And actually, that setup would keep the water continuously moving, and a portion of it being reheated to fairly lethal temperatures quite frequently, so it may actually not be such a bad thing for the health side of it too... interesting. I imagine this setup would work much better combined with the smart circs though so that it could ramp speed way down with low load, and do it much more efficiently? Seems like another project for when the time comes to make those major capital changes...

    In the meantime, any other smaller things I can do at the loop piping itself to reduce noise? Most urgent need is to do whatever I can/need to do to the piping while I have access...

    Thanks again for the help and experience.
  • ZmanZman Member Posts: 6,336

    There is no new water introduced. The cooler return water is just recirculated. The taco I Series is a good one. Look in the instruction manual and it will all make sense.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • MTCMTC Member Posts: 182

    Thanks Carl, that Taco instruction manual was actually a lot more informative than I'd expected. Makes enough sense.

    Its meant to be used on a boiler system with primary/secondary, which isn't necessary on my system, so I assume I'd just pipe it in to the main loop, as shown in pics?

    First pic is rough schematic of my current setup, second adding the valve. Would it be as simple as this, with my open system? I don't have any sophisticated controls, so I assume I'd just hardwire the valve to the whole heating system's power, so that anytime the system is powered up, the valve is also powered?

    Any other thoughts for what to do with the tubing while I have access, or are the steps I mentioned already pretty much all I can do on that end?
  • RobGRobG Member Posts: 1,850

    Can you post some pictures of the piping layout? It will make it allot easier to figure out the best method for your system.

  • MTCMTC Member Posts: 182


    Do you mean what I just posted about the same time you did, or of the zones/circuits themselves?
  • MTCMTC Member Posts: 182
    edited May 2014
    Tubing Layout

    The joists in this house are 16" centers in some areas, and 24" centers in others. The piping layout is slightly different in the 2 cases, as illustrated (hopefully legibly) in the drawing.

    3/4" pex manifolds to each zone (one zone per floor, 3 floors). First 2 floors are 4 circuits on each zone, 3rd floor is smaller and only 2 circuits. Circuits are 1/2" pex on 8" centers. Stamped double tube plates installed about 4" from each other on the 16" bays, and almost touching each other on the 24" bays, but alternating back and forth between pairs of piping. So the pipe returning down the middle is continuous contact with plates, the hotter lines on outside are in contact with plates 1/2 of the time, if that makes sense.

    Circuits are very close to each other lengthwise, I think around 275' each. Pex is non-O2 barrier, as its an open system and constantly exposed to fresh oxygen rich water anyway. My understanding is that the non-O2 pex expands/contracts less than the O2? So this would work in my favor at least, if that's the case.
  • SWEISWEI Member Posts: 7,356
    PEX expansion

    is the same for barrier and non-barrier as far as I know.  If anything, the barrier would potentially inhibit some of the expansion -- can't see how it could add to it.

    I'd install an HX with an ODR-controlled mixing valve on the floor loops.  You really want to modulate those temps -- not just for noise, but for comfort.
  • MTCMTC Member Posts: 182

    I don't have any real scientific reason for that claim, or necessarily believe it...

    I've just heard that some less scrupulous installers were using it as a means to quiet down staple up pex systems as it expanded/contracted less than O2. No idea if that's true or not, but on a closed system, this is obviously a big problem.

    Right now I'm interested in what I can do to exposed tubing, that will be available only once, possibly next week. The steps I took on the first floor seemed to make a significant difference, and I plan to do those things to 2nd floor while I have access. Is there anything else that would be beneficial to do to the tubing while I have it exposed?

    Not really interested in adding a HX... know everyone here seems to hate open systems, but I like it and see no good reason to change it in that way. The ODR mixing valve seems like it could be a good addition, just need to think through it a bit more/get some input from others here about its overall impact on legionella risk... nearly zero stagnation is a huge plus, but lower temperatures a bit of a minus. Seems like enough water would be heated back up to high temp often enough that it would work out as a positive step in the end with all the added circulation...

    Thanks for the input.

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