Solution suggestions for exhaust condensation issues....

[Ryan Gallagher]

If I could determine the spots suffer similar condensation problems that would be my winning argument for a motorized version or at least a passive backdraft fail safe. Cause our ops in that department are often very green to our booth, if not green to running spots entirely, easy to miss non-obvious steps.

For analog projection, we are committed to a two projectionist booth now because of how much day of pre-show/backup/post-show we often run manually via the DCI system. Better to just let 35/70 changeovers be the only task for the other person without distraction. But if we are both 35mm projectionists, which we often are, we tend role share a little, and not role sharing exactly the same every time can lead to a missed step in the sequence. So again an argument for some failsafe approaches to this one.

[Ryan Gallagher]

We also tend to invite/employ guest 35mm projectionists, to be the second along with a house staff projectionists, in an effort to deepen our local pool of individuals familiar with our booth and setup. At least once this summer season one of our staff was on vacation, and I caught covid, I had to walk our guest through booth startup and shutdown over the phone... certainly easy to miss a step when describing it from memory. He had only been in the booth one time prior in that context to run a house practice print, and inspect the show print.

A good example was that he thought he had a bad 35mm power supply.. cause after the step of turning on those breakers, I did not warn him they are installed in such a way that they won't all face the same direction in the on position. He thought one was on already and did not flip it, but took us a few minutes to figure that out over the phone.

[Brad Miller]

We also tend to invite/employ guest 35mm projectionists, to be the second along with a house staff projectionists, in an effort to deepen our local pool of individuals familiar with our booth and setup. At least once this summer season one of our staff was on vacation, and I caught covid, I had to walk our guest through booth startup and shutdown over the phone... certainly easy to miss a step when describing it from memory. He had only been in the booth one time prior in that context to run a house practice print, and inspect the show print.
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And then you return and wonder why the light is poor on screen, then you find this (see pic). Even if the house projectionists never forget to open and close the dampers on changeovers, one of those occasional guest projectionists, who would be nervous since it's not a booth he runs each week, sooner or later will forget. Now you've REALLY got problems! Have any spare reflectors on site? How much time and money will it take to source replacements?

Remember you can't just call up Strong and order replacement parts anymore. A film booth in 2024 is simply not a place to boil water.

[Ryan Gallagher]

Oof. That just a cooked reflector? I’d hate to see what flashing a quart of condensation to steam looks like.

Thankfully we do have two backup reflectors in our back room. They have more pitting than our current ones, but almost nothing gets thrown away arsonist here.

[Tony Bandiera Jr]

I was thinking about something like that being tied to the circuit. No doubt would help some, but that style seems to be more about impeding flow, not so much fully sealing. I expect the warm air would easily sneak around that louver when the system is off for weeks at a time.

I’ll do some research on one way passive systems.

Brad is spot on, as usual. Motorized dampers are the way to go, they would, if properly wired, be almost 100% foolproof. And in your follow up posts, I see your bosses may try to argue costs. Ok, 4 or 5 of those dampers (do the spots too) would run around $500 Add maybe another $500 to get them wired in by a tech.

Now price replacement reflectors and xenon bulbs....as you'll quickly learn $1,000 to install those 4 or 5 dampers is chump change vs. the costs to replace reflectors and bulbs in projectors and follow spots.

And if they still don't listen....'em. You've documented the issue on here, and when things go pear-shaped due to their penny pinching...calmly say I warned you about this....

[Paul H. Rayton]

And while you're at it (and I'm not too sure what kind of wiring connections are available with the motorized dampers), you should figure out some kind of visual indicator to alert if the airflow is NOT happening. You may have a vane-type airflow switch already in the stack, but somewhere along the line, it would be a nice idea to have a red warning light to come on if the damper fails to open and airflow is not happening. A red light alert ("no airflow", or comparable) would immediately inform whoever happened to be there that the airflow is in FAIL mode, and to start checking for the problem. It could be tied to the damper device, or the vane switch. It's a bit of an extra frosting on the cake, but if (as Ryan mentioned) he sometimes has visiting projectionists in there, this airflow is mission critical. A quick diagnostic fix to a FAIL problem could save an evening show.

[Ryan Gallagher]

And in your follow up posts, I see your bosses may try to argue costs.

Budgets for maintenance and improvements is an issue for sure, but our real problem is that the theatre has been "slated" for a major restoration for about a decade now... they are closer than ever with the fundraising to make it actually happen, but it is definitely still at least 3 years away.

Everything that isn't actually fixing something broken tends to get waived off with "well do it during the renovation". For example on this front... the DCI projector is probably getting an upgrade to laser 4k, and he's considered pitching NEW Cinemecannica projectors (since they started making them again). Though compared to the Century JJ's i'm not sure that is actually an upgrade, it's just a company you perhaps can get parts from still. Rather than modify the existing exhaust they've discussed ripping out the whole system for a new roof blower and stacks.

But in the mean time... here we are still risking water ingress and damage to the gear we currently use.

Perhaps it's one of those "don't let perfect be the enemy of good" situations. And it would only take minor $$ to achieve "good" on this front.

[Brad Miller]

And while you're at it, you should figure out some kind of visual indicator to alert if the airflow is NOT happening.

Excellent point and one trivially accomplished with an automation monitoring the status of everything. Without an automation though, something as simple as a separate low voltage power supply running through a microswitch that drives a red or green LED, depending on whether there is airflow pulling the featherswitch up or not. The idea would be to route that power source through whatever the manual control point is (possibly the projector motor's relay) so when the system isn't running, neither LED is on, but when the system is running, either the red or the green LED is on. To help projectionist-proof it further, a low volume buzzer could be added to the "red" relay side of the microswitch so a constant buzzing happens when the system is running without exhaust to make the projectionist look around thinking "what's that noise" to ensure they see the red LED warning.

And yes you would want that green LED, not just the red LED so if that little power supply ever failed, at least there would be a decent chance that the projectionist would notice that there was no exhaust status light on. There is a reason why you would want to keep the LEDs on a separate power supply though, as if the LED/buzzer power source failed, the exhaust dampers would still be working fine, it would just the the visual and audible alert system that failed. However the real reason for separate power supplies is that if the exhaust damper's power supply ever failed, the projectionist would get the red light and buzzing to alert of a problem and they could then flip the damper open/closed by hand to get through the show. If both the dampers and the LED/buzzers were fed from the same low voltage power supply, and especially if the "green" LED was omitted, if that one supply ever failed nobody would have any idea anything was wrong.

All that would be needed to make-your-own featherswitch like you would find at the exhaust connection of a lamphouse is a microswitch with a long actuator lever and a cut-out piece of a Coke can attached to the end of it. Some bendable strapping material and there you have it. The parts cost would likely be under $20. Still though if the booth is going to get a retrofit and money will be blown on a "pew pew lazer" digital projector, there is no excuse not to add a proper automation system to the booth. It could watch over the film shows as well as assist with digital shows as well.

And yes, yes, yes don't panic...the projectionist could STILL press the changeover buttons manually.

[Ryan Gallagher]

Excellent point and one trivially accomplished with an automation monitoring the status of everything. Without an automation though, something as simple as a separate low voltage power supply running through a microswitch that drives a red or green LED, depending on whether there is airflow pulling the featherswitch up or not. The idea would be to route that power source through whatever the manual control point is (possibly the projector motor's relay) so when the system isn't running, neither LED is on, but when the system is running, either the red or the green LED is on. To help projectionist-proof it further, a low volume buzzer could be added to the "red" relay side of the microswitch so a constant buzzing happens when the system is running without exhaust to make the projectionist look around thinking "what's that noise" to ensure they see the red LED warning.

And yes you would want that green LED, not just the red LED so if that little power supply ever failed, at least there would be a decent chance that the projectionist would notice that there was no exhaust status light on. There is a reason why you would want to keep the LEDs on a separate power supply though, as if the LED/buzzer power source failed, the exhaust dampers would still be working fine, it would just the the visual and audible alert system that failed. However the real reason for separate power supplies is that if the exhaust damper's power supply ever failed, the projectionist would get the red light and buzzing to alert of a problem and they could then flip the damper open/closed by hand to get through the show. If both the dampers and the LED/buzzers were fed from the same low voltage power supply, and especially if the "green" LED was omitted, if that one supply ever failed nobody would have any idea anything was wrong.

All that would be needed to make-your-own featherswitch like you would find at the exhaust connection of a lamphouse is a microswitch with a long actuator lever and a cut-out piece of a Coke can attached to the end of it. Some bendable strapping material and there you have it. The parts cost would likely be under $20. Still though if the booth is going to get a retrofit and money will be blown on a "pew pew lazer" digital projector, there is no excuse not to add a proper automation system to the booth. It could watch over the film shows as well as assist with digital shows as well.

And yes, yes, yes don't panic...the projectionist could STILL press the changeover buttons manually.

All good ideas. Our current DCI setup exhausts into the booth with a ceiling mounted blower. Apparently everyone got cold feet about adding it into the existing roof exhaust... and it's vintage blower, along with the headache of punching a new hole in the plaster and metal lath ceiling. Maybe the CFM in the shared situation was not solid enough. So a redo of digital certainly doesn't mean anyone will want to do it next time either. That and laser may not even need the blower exhaust.

[Ryan Gallagher]

Recovery to the status quo is at least official. Screened a relatively gorgeous print of “I Am Love” tonight. A bit of dirt but not a scratch or splice to be seen.

Will keep begging for exhaust parts after the summer series closes Sept 1st.

[Paul Finn]

For the booth retrofit I vote for Cinemeccanica 35/70s. They are built like a tank. You will love them.

Paul Finn

[Tony Bandiera Jr]

Excellent point and one trivially accomplished with an automation monitoring the status of everything. Without an automation though, something as simple as a separate low voltage power supply running through a microswitch that drives a red or green LED, depending on whether there is airflow pulling the featherswitch up or not. The idea would be to route that power source through whatever the manual control point is (possibly the projector motor's relay) so when the system isn't running, neither LED is on, but when the system is running, either the red or the green LED is on. To help projectionist-proof it further, a low volume buzzer could be added to the "red" relay side of the microswitch so a constant buzzing happens when the system is running without exhaust to make the projectionist look around thinking "what's that noise" to ensure they see the red LED warning.

And yes you would want that green LED, not just the red LED so if that little power supply ever failed, at least there would be a decent chance that the projectionist would notice that there was no exhaust status light on. There is a reason why you would want to keep the LEDs on a separate power supply though, as if the LED/buzzer power source failed, the exhaust dampers would still be working fine, it would just the the visual and audible alert system that failed. However the real reason for separate power supplies is that if the exhaust damper's power supply ever failed, the projectionist would get the red light and buzzing to alert of a problem and they could then flip the damper open/closed by hand to get through the show. If both the dampers and the LED/buzzers were fed from the same low voltage power supply, and especially if the "green" LED was omitted, if that one supply ever failed nobody would have any idea anything was wrong.

All that would be needed to make-your-own featherswitch like you would find at the exhaust connection of a lamphouse is a microswitch with a long actuator lever and a cut-out piece of a Coke can attached to the end of it. Some bendable strapping material and there you have it. The parts cost would likely be under $20. Still though if the booth is going to get a retrofit and money will be blown on a "pew pew lazer" digital projector, there is no excuse not to add a proper automation system to the booth. It could watch over the film shows as well as assist with digital shows as well.

And yes, yes, yes don't panic...the projectionist could STILL press the changeover buttons manually.

And that is super simple to implement. Wire the power supply, microswitches and LEDs as follows: Power supply DC out (-) to all LED's negative side, Power supply (+) to ALL microswitches' COM terminal. Red LED (+) on each switch with the correct series resistor inline to the Normally closed (NC) terminal on the microswitch, and the Green LED (+) with series resistor to the Normally Open (NO) terminal on the switch. Easy peasy lemon squeezy. You can easily power multiple of these with one small 250ma to 500ma wall wart supply. (up the supply to 1a if you want warning buzzers) The resistors value will be determined by the power supply voltage. For 24v 1.33k ohms, for 12v 550ohms. (or nearest available values.) Those values will drive the LED's at 5ma. For longer life and driving them at 2.5 ma, 12 would be 650 ohms, 24v would be 1.6k ohms. Select the appropriate voltage for the warning buzzers, and they would connect with buzzer (-) to power supply minus, and buzzer (+) direct to the NC terminal on the switch.

Turn that power supply on or off with any switch or circuit breaker that has to always be on when using the booth equipment. (power to sound or lighting board would be best, if you use the exhaust fan breaker/switch and someone forgets to turn on the exhaust fan the system will not work. If you're using buzzers though, any show not requiring spots or projectors would have them all sounding off...in that case you'd be better off tying to exhaust fan power, but at the risk of not having a warning if someone forgets to turn on the fan.)

[Brad Miller]

Turn that power supply on or off with any switch or circuit breaker that has to always be on when using the booth equipment. (power to sound or lighting board would be best, if you use the exhaust fan breaker/switch and someone forgets to turn on the exhaust fan the system will not work. If you're using buzzers though, any show not requiring spots or projectors would have them all sounding off...in that case you'd be better off tying to exhaust fan power, but at the risk of not having a warning if someone forgets to turn on the fan.)

Assuming there is one breaker that feeds 110v to both projector motors (along with possibly other things in the film projector system), connect the power supplies to that. This way if the projectors are shuttling film then the exhaust "alarm" would be active.

[Ryan Gallagher]

Assuming there is one breaker that feeds 110v to both projector motors (along with possibly other things in the film projector system), connect the power supplies to that. This way if the projectors are shuttling film then the exhaust "alarm" would be active.

Yeah the easiest for us is either motor power, or we have the pedestal base outlets on another breaker (which drive the optical diodes etc). Exhaust circuit is a no go because yeah, would want it closed and not alarming while only spots are operating.

After my technical manager came up to the booth to talk about it, he seems more willing to do the necessary things to resolve this before next summer film series. He operates best if you hand him an exact purchase list and plan, though in this case he wants venue operations involved too since he considers some of that exhaust equipment to be in their domain. I'll pretend it's entirely my project and give them something to approve. The indicators and flow monitoring stuff can come after the initial effort. Will try to convince em of the motorized option... but he was obviously leaning towards replicating what was done for the spots... which is just a fancier version of the manual solution we already have. Le Sigh.

[Ryan Gallagher]

Alternative to making my own basic indicator... there are some reasonably priced airflow switches/sensors out there:

Basic Airflow Vane Switch: 27$
https://bravocontrols.com/shop/air-flow-switch/

Fancy Version: Differential Pressure Averaging Pilot Tube and Sensor (0-10v): 56$
https://bravocontrols.com/shop/air-flow-sensor/

I don't believe that pilot tube unit is rated for an appropriate temp range for xenon exhaust stack though. Only rated to 60C/140F for HVAC.

Here is a high temp stainless pilot tube... but at quite the price difference i'm sure. But anyway, fun to think about pressure sensing as a way to monitor the health of the blower on the roof, perhaps not realistic.
https://easterninstruments.com/products/vap3.html