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Crackling Runtals

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stonebutson
stonebutson Member Posts: 24
Runtal - hi guys, I sleep next to a couple of 3 foot runtal radiators that are making a crackling noise. I was very meticulous about expansion when I installed the zone and pretty sure it isn’t that. The zone is constant circulation (tekmar reset) off a primary/secondary system. The system circ is a grunfos on low speed. The boiler circ is a taco 007e. It seems like every time the boiler circ starts I get the crackling noise (all night long) Does the boiler circ act in series with the system circ and I suddenly get a blast of velocity? You know how it is guys - we lie in bed and hear every circ, zone valve, relay, gas control valve. Any ideas would be appreciated.

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  • hot_rod
    hot_rod Member Posts: 22,261
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    Any control or shutoff valves on the radiator? When a valve closes down to a small opening you sometimes can get some cavitation noise.

    Air bleeder on the radiator?
    Circulator sized correctly?
    Any pressure bypass valve or delta P circulator on the system?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mattmia2
    mattmia2 Member Posts: 9,747
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    I have one that does similar things. It pops and cracks with temp changes and sometimes when the ciruculator stops and the zone valve closes (the circulator is run off the end switch on the zone valve) there is as somewhat more distinctive metallic ping. It seemed to have been worse before all the last vestiges of air worked out of the radiator.

    I think the panel itself creaking and tapping is a result of it being hung on a wall with a belly. Over the summer I plan to remove it and shim out the mounts so they all sit in one plane. It is a 9 ft 4 tube panel.
    stonebutson
  • stonebutson
    stonebutson Member Posts: 24
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    Thanks - they are set up reverse return. No velocity problems anywhere else. No zone valves system runs constant. System grundfos 15-58 is on low speed. Matt described it perfectly- it’s distinctive metallic sound. The only time I hear it is when the boiler pump kicks in. I do have balance valves I think I will try throttling them down. I know runtal wants low and slow. Thanks
  • mattmia2
    mattmia2 Member Posts: 9,747
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    I think the Runtal spec is max 1.5 gpm per tube but it obviously would work with a much lower flow if you can move enough heat at that flow.
  • HomerJSmith
    HomerJSmith Member Posts: 2,468
    edited January 2020
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    Is this baseboard or flat panel radiators?

    Did you open up the bleeders (coin vents) to extract all the air out?
  • stonebutson
    stonebutson Member Posts: 24
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    Two three foot, three tube wall mounted baseboard. No shut valves. Air all bled out. Piped reverse return. Boiler is piped primary/secondary. Sound happens when boiler pump (taco 007e) kicks in.
  • hot_rod
    hot_rod Member Posts: 22,261
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    If you can run constant circulation, or a finely dialed in ODR you can minimize on/ off and noise caused by expansion- of the metal.

    TRVs really can dial in panel rad performance. They are a non electric, proportional control device that all but eliminates on off operation for the most part

    You can add timer control on most brands if you like night setback for example in sleeping areas.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream