S4 max ambient temperature for max lamp life?

Discussion in 'Lighting and Electrics' started by lightingman117, Jun 1, 2018.

  1. lightingman117

    lightingman117 Member

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    Cross posted to PSW: http://forums.prosoundweb.com/index.php/topic,167532.msg1545856.html#msg1545856

    ETC Source 4 (S4) 575w fixtures
    Ceiling Cove = 6ft x 1.5ft x 2.5ft (L x W x H)
    Air conditioned room year round.
    The current coves have a grate that opens to the attic. Venue wants to close that off so that the attic heat doesn't get into the room.

    Concerned that the increase in ambient temperature (can't escape to attic) will decrease the life of the lamp.

    ETC says best practice is to have constant airflow to "increase the life of the lamp" though they have no study to support this claim.

    My problem with thinking ambient temperature determines life of lamp is that the ambient temperature is so small compared to the temp of the lamp as to be inconsequential. https://what-if.xkcd.com/155/

    http://www.calculator.net/btu-calculator.html

    Temp controlled Fan option:
    https://www.amazon.com/dp/B000M4W2DM/?tag=controlbooth-20
     
  2. Amiers

    Amiers Renting to Corporate One Fixture at a Time.

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    Well heat rises. So I don’t see the attic heat pouring out like they think it will.

    I think they are super over thinking it.

    If they are super worried and feel like spending money they can put in a bathroom fan to suck air up to the attic. Could go so far as to thermostat control it even. Might save a days worth of lamp life.
     
  3. lightingman117

    lightingman117 Member

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    Agreed. I said plug the holes and I doubt you'll see any noticeable lamp life difference. There might be a statistical difference, but it's going to be small.

    Mostly the humidity/temp close to the ceiling is an issue causing mold buildup. They're trying to get the AC bill down as they're having to keep the room cooler all the time.
     
  4. JohnD

    JohnD Well-Known Member Fight Leukemia

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    They might also want to address the ventilation in the attic space. Usually you want an inlet for fresh outside air coming into the attic at a lower elevation and the hotter air venting outside at the highest elevation. Having good attic ventilation can also extend the life of the roofing.
     
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  5. FMEng

    FMEng Well-Known Member Fight Leukemia

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    I think excess heat will drastically shorten the life of the instruments. I have similar ceiling boxes with Strand Lekos, and have observed the following over 25 years of operation. I doubt the heat affects lamp life much but it does kill the ellipsoidal reflector. Some of ours had discolored reflectors, damaging the light output and color temperature. The oxidation of the reflector surface is hard to see, but the effect is obvious. Once I noticed the trend and allowed more air flow through the box, the problem subsided. More heat also shortens socket life.

    The best compromise would be motorized dampers run by a hydraulic bulb thermostat. When the lights start heating the box up, the thermostat opens the dampers. Any competent, commercial HVAC contractor should be able to do the installation, and it should not cost more than replacing a few toasted Source 4s.
     
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  6. Les

    Les Well-Known Member

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    An interesting study would be to see which is a bigger drain on the AC system - open hole where cool air can escape, or introducing these fixtures' heat in to the room, considering it previously vented in to the attic.
     
  7. lightingman117

    lightingman117 Member

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    10hrs per week of 2k BTU/ fixture * 14 fixtures = 280k BTU's

    vs

    Attic venting 24/7 BTU + 50% (wild guess) light BTU?

    Who knows?

    Attic is vented properly as per commercial building standards. Over on my PSW post Tom states that the 350℉ creates some convection currents already. Is it enough? (rhetorical)

    Nice points.

    Temp controlled fans would probably be the next step. They're cheap and easy to implement.
     
  8. JD

    JD Well-Known Member

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    I assume that the HVAC vents are in the normal ceiling section, and that there are no ceiling fans that push air down. Under those circumstances, there is a natural heat gradient in any room with the floor being coolest and the ceiling being hottest. Without a mixing element, AC can coexist with hot air near the ceiling. I don't see a significant cost savings for the venue to close them off unless there is a positive pressure above the ceiling forcing the hot air downward.
     
  9. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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  10. lightingman117

    lightingman117 Member

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  11. JD

    JD Well-Known Member

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    They are hung almost below the coves so I don't think it will affect them as much, especially as there will be a ceiling level swirl from the HVAC vents. Small vent fans (like a bathroom vent) connected to thermostats in the boxes, set at 100 degrees would help and save them money by removing the heated air from the room.
    A bigger problem might be the bases of the movers, which contain the electronics, being subjected to preheated air. May cause early failures in those electronics.
     
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  12. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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  13. FMEng

    FMEng Well-Known Member Fight Leukemia

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    The pictures change my opinion. I think the S4s have enough air movement to be fine. I would worry about the mover, though. At the least, hang it lower so that the electronics are where there is more air movement and lower temps.

    I am skeptical about the bathroom fan idea. Not only do they tend to be noisy, but the motor bearings would be subjected to the temperature of the exhaust air. They won't last long under those conditions because permanent lubrication isn't really permanent.
     
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  14. JD

    JD Well-Known Member

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    I used the work "like" because of the noise issue, but there are plenty of small vent fans and some duct booster fans that run pretty quiet. Object would be to dump the air from the box if the temperature got above X degrees. Still, I suspect nothing needs to be done about the S4 fixtures because they are hung low. Capacitors drying out in the electronics of the movers over time would worry me.
    Here's another thought, see if someone in the HVAC department could run some 3 inch flex-duct from the AC ducts and vent them into the boxes. getting a little air moving around may prevent the heat buildup without adding any noise.
     
  15. lightingman117

    lightingman117 Member

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    Ohh that's a good idea!

    Aight, glad my gut reaction was along the correct lines.

    I'll inform them covering the holes won't hurt the lights, but adding some cooling specifically for the movers might be a good idea :)

    Thanks everyone!
     
  16. Chase P.

    Chase P. Well-Known Member

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    What about a couple of little brushless fans? They're nearly silent, cheap as chips on Amazon, and compact enough to fit almost anywhere. Get the 120v versions, and they could go on the same power as the mover, thereby only being on when it is.

    They'd do a fair bit to just keep the air moving, same as the 3"duct idea, but without calling in an HVAC contractor.
     
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  17. Jay Ashworth

    Jay Ashworth Well-Known Member

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    If you dump chilled air into those coves, aren't you going to have condensation problems?
     
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  18. RonHebbard

    RonHebbard Well-Known Member Premium Member

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  19. JD

    JD Well-Known Member

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    Shouldn't. As air heats up, it drops in humidity so it would be a drying effect. Now if hot moist air were entering a cool pocket, then there would be a problem.
    As Ron mentioned above, the condensation occurred on the outside of the ducts as hot air cooled on the chilled metal.
     
  20. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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