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Hydronic system - loud manifold clanging when actuators turn on / off

Midnight
Midnight Member Posts: 4
Hi all, I'll start with the disclaimer - I am a total layman but have spent the last couple of hours learning about hydronic heating systems as the technicians my landlord has had in to deal with this system cannot be relied upon..

In summary, for some inexplicable reason, the zone control panel was installed in our master bedroom, and makes an extremely loud clanging, banging, and clicking sound that lasts 15-30 seconds when heating zones come on and off. Sometimes these are mild but at other times it can be heard across the suite and sounds like the walls are about to explode.

Finally, my landlord had someone in to look at the problem and tried to mitigate it by bleeding the system of air (in theory), but this sound is still happening (albeit possibly milder).

Here is what I discovered when trying to diagnose the problem myself:

  • One of the actuators was left completely uninstalled (I reinstalled it), which explains why our bathroom floor was boiling hot for the last two days and the loud whooshing sound behind the panel of unrestricted flow
  • We have three thermostats and three zones. Today I discovered that one thermostat controls four actuators and another thermostat does nothing. That explains a few things.. Unfortunately I don't have access to any other parts of the system so I don't know if I can fix this as I don't want to deal with live wires, even at 24V.
  • The supply and return manifolds were hooked up in reverse. I am not sure the consequence of that, but I have noticed that the flow meters read at zero even when water is flowing through the zones.
Ok, and to come to the main point. The clanging sound happens as the actuators come on and off and exactly corresponds to the flow meters also fluctuating wildly. I can link to a video if that would help. The question is - what is the possible cause of this issue and is there something I can do to fix it, especially not having access to the rest of the system?

Comments

  • Canucker
    Canucker Member Posts: 698
    Most likely you have a fixed speed pump. It can't vary the flow rate, so when your zone valves close they bang because the pressure rises trying to force the water through it at the same rate. There should be a pressure bypass installed to alleviate this or if it isn't available, there are pumps available that can adjust flow rate based on the pipe resistance.
    You can have it good, fast or cheap. Pick two
  • hot_rod
    hot_rod Member Posts: 14,871
    Make sure the flow direction is correct, those actuators need proper flow direction. What is the circulator brand and model?
    Try slowing the pump speed if possible as @canucker mentioned or replace with a delta P style circulator.
    Some manifolds have pressure bypass valves that go on the end.

    Hopefully it is wired through a relay box so the circulator shuts off when all zones close
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Canuckermattmia2
  • Midnight
    Midnight Member Posts: 4
    hot_rod said:

    Make sure the flow direction is correct, those actuators need proper flow direction. What is the circulator brand and model?

    Try slowing the pump speed if possible as @canucker mentioned or replace with a delta P style circulator.

    Some manifolds have pressure bypass valves that go on the end.



    Hopefully it is wired through a relay box so the circulator shuts off when all zones close

    So the flow through the manifold is definitely in the wrong direction (as you can see in the temperature gauges in my photo), but how do I know if these actuators meant to go on the "real" supply or return end? They still control the zones properly but could that explain the clanging?

    Unfortunately, this is the only part of the system that I have access to from my suite, so I can't check the circulator.
  • That Rehau manifold is built for actuators on the return side and the ProBalance gauges on the supply. It totally explains the clanging as those valves are meant to push against flow, not with it.

    Someone will have to get in there and switch the PEX pipes.
    Often wrong, never in doubt.
    MidnightSuperTech
  • Midnight
    Midnight Member Posts: 4

    That Rehau manifold is built for actuators on the return side and the ProBalance gauges on the supply. It totally explains the clanging as those valves are meant to push against flow, not with it.

    Someone will have to get in there and switch the PEX pipes.

    Awesome, thanks Alan. I'm curious - are you able to explain specifically what's happening inside the valve when it pushes / closes with the flow to cause this clanging?

    Would this reversed hookup also explain why the flow meters are reading zero?

    Finally, you are talking about the two PEX pipes on the main circuit, correct? As the actuators and flow meters are installed on the correct manifolds, but the manifolds are hooked up to the wrong ends of the system.

    Thanks!
  • hot_rod
    hot_rod Member Posts: 14,871
    Or flop the manifolds, upper to lower, lower to upper. You have unions on the manifold, and nuts on each loop.

    Here is a cutaway of a Caleffi brand, most function the same way. The valve mechanism has to push down on the port to stop flow.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Midnight
  • Mr. Midnight:

    I'm not sure about how it causes the clanging. When I think about it and how the valve starts closing down, as it gets closer to the valve seat, instead of water flowing against the valve, it's flowing with the valve and as the valve gets closer and closer to the valve seat, the flow will cause the valve to chatter against the seat.

    How's that?

    (Please read moniker below.)
    Often wrong, never in doubt.
    Brewbeer