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Noisy pump

Chris_51
Chris_51 Member Posts: 24
I'm doing a radiant floor in an upstairs bathroom that uses a feed from a radiator.  There is a little rattle noise in the pomp.  I figured it was air, but we did everything to flush it and its still there. 



I have a single pipe hot water system that was converted from pure gravity a while back.  I'm not sure if there are diverter tees.  If there are, then the return of the floor is going down the feed line.  The noise resonates down to the basement.



Any ideas?

Comments

  • Chris_51
    Chris_51 Member Posts: 24
    picture

    picture
  • icesailor
    icesailor Member Posts: 7,265
    Engineering:

    That noise you hear? The Engineer died.

    That's the body of the dead engineer that designed the thing.

    Often I say, "That might work for you. I've never seen it work for anyone else, but it might work for you".

    It didn't work.
  • Zman
    Zman Member Posts: 6,703
    Aside from...

    Aside from the obvious, get the circulator out of the dirt and support the piping properly.

    I think it is likely that the noise you are hearing is coming from the mixing valve. Those are really designed for domestic hot water systems and tend to make a noise that sounds like a small nail is stuck in the pipe. Changing the pump speed may help as may proper pipe support.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Chris_51
    Chris_51 Member Posts: 24
    another mixer

    Is this a better quality mixer?  This was from the original install in the kitchen that worked well.  The supplier is old and pretty set in his ways sometimes.  He is the only guy I know to buy stuff from.  The sound is just like you said.  I'm not sure on the supports.  I'll ask the contractor.  Its a small space available so its a bit crammed.
  • Chris_51
    Chris_51 Member Posts: 24
    pressure?

    I asked the contractor to get another mixer.  The guy at the supply shop said he thinks the pressure is too low on the top floor to get the bubbles out of the pipes.  He suggested turning up the pressure for a while to get it to clear.  The thing is, with a single pipe system, there is no way I know of to do that.  Its just a parasitic gravity flow through the radiators. 



    I can see the top floor having less flow, but I don;t see how that matters for bubbles if we ran a garden hose though at full blast to try to remove the bubbles.



    The supply guy is a pill.  If I call him, he is short with me and tells me to have my contractor call.  This job is wrapping up, so I'd like to get this resolved before the final payment.



    Any suggestions? 
  • Gordy
    Gordy Member Posts: 9,514
    Pressure

    Helps keep air entrained/ in solution with in the system allowing to get back to the air separator.



    Two things drive air bubbles out of solution heat, and low pressure.



    Purging with a garden hose is no guarantee that air is not in the system. Once water is heated micro bubbles come out of solution, and form large bubbles in low velocity areas in the system, and hang there.



    Is this the cause of a noisy circ. can't answer that.
  • Chris_51
    Chris_51 Member Posts: 24
    hmm

    Thanks.



    We started by diverting all the water from the system to the toilet for a few minutes.  There were definitely bubble sounds that cleared though. Now its a more constant noise.  I have bubbles in my pool filer that has a heater in the basement.  Its a different sound to me, but who knows.



    We haven't run heat yet, just cold water testing.  I have this big ole o2 remover thing on the boilers.  It was expensive if I remember.  Would heat clear any air eventally?



    My gut tells me that is the 3 way is made for domestic HW, then it should be replaced with something like the heatway on my other system.   The contractor is going to want a final payment tomorrow, so I'm sort of hosed. 



    The other picture is a good use of boiler room space.
  • hot_rod
    hot_rod Member Posts: 14,834
    all about flow rate

    small 3 way thermostatic mix valves have a Cv around 3. So 3 gpm with1 psi drop, not a problem. Start flowing 8, 10 or more gpm and they will start to talk to you.



    if you oversize a mixer valve, choose a 10 Cv valve, for example, and try to move low flow, the valve will not respond well, and provide in-accurate temperatures.



    Determine what gpm the loop requires and select a mix valve with a Cv as close to that as possible. High flow residential mixers, usually have around a 5 CV.



    Here is a spread sheet to calculate the pressure drop.



    Take a 3 Cv valve, flow 10 gpm and notice the pressure drop. 10 gpm through a 3/4 pipe or valve, IF you have enough pump to provide that, would be over 6 feet per second, 4 FPS is the general flow rate to design hydronics around.



    Also connection size doesn't always change the Cv, plenty of 1" valves with 3 CV.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • RobG
    RobG Member Posts: 1,850
    HR

    I don't mean to get the thread off topic but could you send me or post the actual spreadsheet for that?



    Thanks,

    Rob
  • Chris_51
    Chris_51 Member Posts: 24
    so the pump is too big or the valve is too small, right?

    Thanks for all the tips.  I asked the contractor to secure the pipes as suggested.  I also aked him to ask the supplier about replacement mixers.



    He is on his way out of the whole project.  I suspect he is leaving me with this as-is.  He left Friday without trying to secure anything.  The message was the supplier has no other valves to try.  The guy at the supplier is smart, but gets pretty stubborn.  I have 1,000 gallons of water in this system, so its pretty unusual.



    So my gut tells me the pump is way oversized.  The supplier tends to do that.  I don't see any specs, so I'll try to track down the model.  The honeywell mixer is supposedly OK out to 10 GPM. The kitchen in my follow up post had a 4 way manifold with a 1/25 hp pump and 1 inch pipes to the mixer and pump.  This looks about the same size, driving a single set up tubes.



    I'm not sure how to measure the flow in the floor.  Is there a tool to do that?



    What I did try was to choke down the flow to the pump.  I turned it down until the rattle went away.  I can hear the water flowing with very, very minor air noises. Totally acceptable to me.  The pump seems to run cool.  My laser thermo says 71F on the outside housing.



    I won't be able to really tell if it heats the floor properly until the fall.  With a single pipe system and no zone, the temp gets modulated.   On the kitchen floor the temp to the pipes changes a bit, but the mass seems plenty to hold the temp and it works fine.  It did test fien with the full flow a few weeks ago.



    So, I think I'm done.  I'd rather not choke down an oversized pump, but I guess its OK.  It might be better to wire in something electrically to slow it down instead of restrict the flow?  Who knows.



    So does this some done, or just rigged?
  • RobG
    RobG Member Posts: 1,850
    Air

    One other thing regarding the air issue. The air will come out of solution when heated. Even if it will be uncomfortable for a short period of time I would run the system to evacuate the air and ensure that it works. I'm surprised that you let the installer out of the house without testing the system.
  • hot_rod
    hot_rod Member Posts: 14,834
    Rob

    send me an e-mail and I'll get that Excel to you. tried a PM, maybe check your junk file?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Chris_51
    Chris_51 Member Posts: 24
    air

    Its not so much that I let him out, its just hat he doesn't know what to do.  So I started this thread.  I do see why mosy people don't consider these types of installs.  Its another thing to mess around with.



    I did run the system yesterday as suggested.  I can tell there is air releasing.  I think that is pretty micu going to collect in teh floor tubes, teh need bleeding.  Its really not going to push back down to the basement from the second floor.  I did already test that the floor heated properly a few weeks ago.  My concern now is whether choking the flow hurt that.  I think I can get it to eventually run quiet without choking the flow,



    The mixer seems to make its noise when its turns 90% to the hot or 90% to the cold side.  That clear up in the middle.  I think I can deal with that.  The pump makes more from the extra air.  I'm pretty sure I can bleed more of that out in the fall when its running all the time.  Worst case, I'll get a new mixer online somewhere.



    Thanks for all the tips. 
  • hot_rod
    hot_rod Member Posts: 14,834
    do you know

    how much heat, or how many gpm you need to move to the zone?



    What is the loop in the bathroom? how many loops, how long?



    Assume 6 gpm max for that 3/4 pex. The valve is fine for that, try the pump on speed 1 or speed 2.



    You don't have valves in ideal spots for purging. Add a valve downstream of that purge valve. With the new valve off, you force all the flow to your vent valve.



    You could add a air separator in the line for air removal, like a 3/4 Discal.



    also the only way to get heat into that zone is for the loop that you connected into to be flowing. Unless you have a constant flow through that zone, you will not have any btus to give this bath "mixed" zone.



    You could have a stuck mix valve, they are easy to disassemble, there is a spring inside to be cautious when you open them up.



    I have run systems like this with the guts removed from the mixer to troubleshoot a flow problem. hard to know exactly what "mixed" temperature you would get, however.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 14,834
    This article

    may better explain the options for piping a mixed loop of a zone like that.





    http://www.pmmag.com/articles/84495-a-little-floor-warming-please-john-siegenthaler
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Chris_51
    Chris_51 Member Posts: 24
    background

    I did heat testing and it fine.  I just have noise issues.  I don't think the loop questions are for my setup  I found the diagram I did back when I decide to to the kitchen floor.  I was concerned whether the existing system would work with the floor connected to an old radiator send/feed.  It worked fine.  I included the diagram.  There are no zones.  The room can be choked off as needed.  So I'm not sure if all the math really helps me.   I can't really change anything except the pump.  Its plenty hot.



    I did look at the setup at my office that we added.  The supplier did spec out an air separator.  I'm not sure why he didn't spec it for the kitchen, or why that one didn't have any air issues.  My guess is that is pulled the water down from the loop, so any bubbles from the floor flowed up.  This one is on the second floor, so nowhere to go.



    Ideally another value would help purge.  But with the main shut offs, its workable.



    I think I'm going to add an air separator and a new mixer  I noticed everything is 3/4 before the pump, then 1/2 after.  EXCEPT a short piece before the pump that reduces to 1/2.   I think the pump can accept a 3/4 pipe with a replacement piece.  I'm not sure if that is worth it or not.



    Does this make sense?
  • hot_rod
    hot_rod Member Posts: 14,834
    If the pump is hot

    and making noise it sounds like a cavitation issue. It sounds like a flow restriction. Maybe a kinked tube, blockage in the mix valve? Simple enough to dis-assemble the mix valve, pull out the cartridge, put the top back on and run it.



    What size tube and how long is the loop that the pump is supplying?



    Pump noise can be caused by air, cavitation, debris or crud in the impeller, worn bearings, out of balance, again debris in the system.



    Cavitation can be caused by a restriction in flow to the inlet side of the pump, pointing to the mix valve or a partially opened isolation valve.



    You have a good central air scrubber, but if the flow is not getting thru your loop, that air removal device cannot remove it.



    You could add a quicksetter, or flow meter to check if or what flow the pump is moving. if you get heat from the zone, it must be moving some flow.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Chris_51
    Chris_51 Member Posts: 24
    hmm

    I guess the guy at the supply shop told the contractor that an air separator needs to be by the boiler to work.  Is that correct?



    It could be a flow restriction, but I'd guess its too much flow.  Choking the flow makes it go away.  I ordered a flow tester to check.  I was curious about the reduction to 1/2 at teh pump inlet.  The tubing and post-pump copper is 1/2, but maybe pre-pump copper should stay should be 3/4.  I'm not a plumber, but I think the connection to the pump can be changed, right?  Is that a called a flange?



    I'll try taking apart the mixer.  It looks cheap to me though.



    Its a 10x12 room.  We started with a 300 foot roll and there was a lot left.  .5 tubes.
  • Gordy
    Gordy Member Posts: 9,514
    edited June 2014
    air seperator location

    It works more efficiently if it sees the hottest water in the system which promotes air coming out of solution which is going to be at the boiler supply.



    I think you have velocity noise coupled with noise/harmonics transfer with the circ so close to the floor.
  • Chris_51
    Chris_51 Member Posts: 24
    I did end up swapping out the 3 way valve and added an air separator. I would have liked the air separator on the hot side, but I was doing the swap myself and I'm only OK at this stuff. Now that we have some cooler temps, I could finally test it out.

    It was fine with cold water. One I added heat, there were some bubbles. The air separator doesn't seem to do mach after a few days. I have one spot to bleed right after the pump. A couple time a day I open that an let some bubbles out. This is going from a loop in the basement to the second floor, so the bubbles are unlikely to get back to the mail loop.

    So far so good on the heat.

    I'm not super happy with the supplier. He says he uses that honneywell 3 way for all the instals and had nothing to substitute. I think this is why nobody I know runs heated floors. Too many issues. I like a challenge though.