Wednesday, November 28, 2007

What kind of actuators are you using?

I'm now working on a maintenance ("Undead") release for Servomaster, which was originally created to provide the driver layer for register or damper actuators (as shown here).

A lot has changed since last modification was made to Servomaster - the code turned out to be rock stable and low maintenance. I could accept that as a sign of the fact that the code is perfect - but I'd rather go the other way and ask if it is so off the mark that you guys are speechless and simply walked away from it because you can't use it.

It would be really nice if you looked at the poll (scheduled to close on December 5 2007) and gave me a hint on what to concentrate on.


  1. How much of an advantage is automatic register control? I live in a mobile home with One Big Duct. I have the register in the first couple of rooms completely closed (and they're still the warmest rooms), and the rest are basically wide open, IIRC.

    I would prefer a more balanced system, but the part that I would like balanced is making the hot rooms cooler, and their vents are already completely closed! :)

  2. Timothy: I suppose you're talking about heating season?

    Sounds like you need to fix the return first - or, rather, add a return - I don't think you have one. Would look like Another Big Duct back to the unit - or the place you have your current return at. Might need registers on the return duct as well - paired with ones on the supply.

  3. It's a mobile home. There is no real return: the furnace is installed in the utility room, which has a door with a large vent in it. Each room has a vent above the door. That is the return air: the furnace sucks air from the utility room directly!

    In any case, I'm not motivated enough to add such a return air system myself... I am more likely to add something like blowers (like, say, large and quiet computer fans) in the return air vents to improve circulation. Might that help? Instead of using actuators to open or close the vents, "actuate" the fans faster or slower instead?

  4. Timothy: first of all, with heating you need return vents (if there's no real return) *at the bottom*, not at the top - that you need with cooling.

    Then - yes, making a real return is exactly what I was hinting at.

    From what I gathered, adding fans in ducts is inefficient - natural circulation and proper sizing are more important. Another consideration - fans would use orders of magnitude more energy than servos or whatever else you use to control the flow.

    Might be a good idea to investigate Manual D.

  5. That's too bad: I was hoping an easy solution might be enough! :)

    I doubt that adding return air ducts would be even remotely cost-effective in the absolute sense. Even as a quality-of-life issue I'm not sure it's worth it.

    However, this spring I will be running network/theater wiring under the house. I'll look around while I'm under there.

  6. Timothy: ouch! Wiring is, indeed, a major undertaking - at least it is if you want to do it good.

    I think once you start taking things apart, though, you will realize that it is not as difficult as it seems - it's just it has to be planned well (which is incredibly difficult to do if you haven't done that before, no matter how good you are) and you have to have tools and materials available (same).

    I hope I'll finish my wiring project soon and publish the complete report. Conduits and wires are in at this time, framing for the server room is mostly done, so it can't take too long :)

    One thing to do: think about upgrading insulation while you're doing something else. Not inexpensive, but well worth it in the long run.