Solution suggestions for exhaust condensation issues....

[Ryan Gallagher]

We learned the hard way (probably for the umpteenth time) this week that failing to block off our 35mm exhaust stacks as we leave the booth invites disaster.

If we fail to do so, for any significant length of time, the outside relative humidity finds it's way to the lamp house surfaces super-cooled by the 63deg booth.

Currently...

Unfortunately our two Strong Super 80s are plumbed to a shared outside air exhaust blower on the roof (shared with the two Strong Super Trooper spotlights). The spotlights have relatively convenient duct gates that can be closed. But the two Century JJs are plumbed to pre-existing "stove pipes" that probably date back to the carbon arcs. There is no gate or one-way valve. We have to remember to slide a piece of luon or fiber-board between the lamp house and the exhaust coupler after cool down. Would share pictures but just got home.

One of our sacrificial boards was getting moldy last time, so we replaced it, but that action threw off our rhythm and we left the replacement sitting somewhere somewhat hidden from view during our cool down. It was not caught and that lamp house became a swamp over 4 days.

Have mostly recovered now and roof blower is air drying everything after removing the lamp and mopping up the bulk of it. No 35mm until the 21st thankfully.

But in a perfect world where outside air is involved, what is the best method to mitigate the worst case, even in the event of operator forgetfulness?

In the short term i'm considering something cleanable and frisbee shaped inverted to catch the condensation in the stack, which isn't much when only the stack is producing the condensation. You start to need a mop when the outside air gets past that into the lamphouse. Re piping the exhaust, adding a gate, including a one way flow activated valve, and using insulated piping within the booth seems pretty obvious, but has been a bridge too far to date despite this issue recurring on occasion.

[Ryan Gallagher]

Hah, actually, for now, I think glow in the dark frisbees is the way to go. Turn the lights off, if the stacks aren't glowing you forgot something.

[Brad Miller]

Motorized dampers will work (get "usually closed" type).

One such example:
https://www.amazon.com/dp/B078PS3XFB

[Ryan Gallagher]

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.

[Ryan Gallagher]

Maybe something more like this (one way backdraft passive damper with rubber seal):

https://www.homedepot.com/p/VENTS-US...50-U/205715170

The one problem would be it would be opened whenever the shared exhaust is enabled. Stealing exhaust air whenever spotlights are in use but not the projectors. Might have to be that plus a manual or electronic damper.

[Ryan Gallagher]

Motorized dampers will work (get "usually closed" type).

One such example:
https://www.amazon.com/dp/B078PS3XFB

Actually your original example does have weather seal foam shown in other photos... so maybe yeah, a motorized one that has a seal, which do seem to exist.

[Randy Stankey]

How about using hand operated butterfly dampers?
You know the kind... They have a handle on the outside that you pull/turn to regulate air flow the way you want.

Put one at each device that needs to have its duct closed off when not in use. When you need it, pull the handle open. When you're done, pull it shut.

Put a red ribbon on the handle in the fashion of the "Remove Before Flight" ribbons you find on airplanes. That way you'll be reminded to open and shut dampers before you start and after you finish.

[Brad Miller]

We have done a number of installs where we had only one exhaust to the roof and 2 (or 3) projectors that had to share it. Using motorized dampers like these, some "T" ductwork connectors and some time delay off relays, as each machine was turned on the damper would open permitting air flow as the bulb struck. Then when the bulb was turned off, the time delay relay would continue to keep that duct open for a few minutes so that bulb could cool, while still providing airflow to the incoming machine.

Note that the exhaust CFM and the size of the bulbs determined the time adjustment needed. Also yes the incoming machine didn't get full CFM levels for the first 2-3 minutes due to this, but it never negatively affected anything as the bulb had just been turned on. Depending on your setup, the hardest part will be to decide where to tie the wires into as there are pros and cons for various connection control points. Having an automation is truly the best way to do this, but the people who are all about "watching the reels spin" and fetishize the whole reel to reel thing will be having an aneurysm at the mere mention of the "a" word for immediate fear they won't get to fap by pushing the button at a changeover. Remember having an automation does NOT mean it must literally run the show and make the coveted changeovers. It can be used quite effectively for external controls and failsafe purposes such as exhaust dampers, turning off the LEDs in your sound readers to extend their life when that machine is not actively on screen, making sure if a film break happened (or tail-out) that the motor and lamp turn off immediately (instead of mangling the end of the film from slapping or burning a lens or a hole in the shutter), etc. Meanwhile the human projectionist can happily co-exist with an automation backup because he still gets to make that coveted, yet less-accurate changeover.

If you don't have some fancy automations (which I don't think you do there) expect to need to do things such as adding in DPDT relays to trigger that machine's exhaust through the time delay off relay where before there was just a switch (for example, to turn the projector motor on/off). If you leave the motorized dampers to another manual switch the projectionist must remember to flip, you WILL at some point or another have problems that will cause an interruption in a show, or pre-maturely kill a lamp because it's being forced to run with no airflow, or the running machine is only getting half CFM because the projectionist forgot to close the outgoing projector after a couple of minutes, etc.

Do note you can always manually override these dampers in the event of a motor failure so you don't have to worry about losing a show in such an instance. Again just make sure you get the "normally closed" variation. Otherwise you have to supply power to the motor constantly when a given projector is not in use (as in overnight or weeks at a time between shows).

Setup properly, this sort of solution eliminates mistakes from the operator forgetting to open and close valves, and also gives more CFM to the currently burning machine as opposed to simply "T" connecting the ducts and making everything perform poorly. Of course the PROPER way to do this is to install another exhaust fan (or two) on the roof, but that is frequently just not an option.

[Randy Stankey]

I like the idea of motorized dampers. It's cool but, sometimes, things like that can be a complex solution to a simple problem.

Years ago, I was working on a student play on the stage at Mercyhurst. There was a scene where one of the characters was sitting in a kitchen, waiting for a kettle to boil in order to make tea. During one of the initial tech meetings, the issue of how to make the tea kettle boil was brought up.

Some people talked about using sound effects to make the tea kettle whistle. Some people wanted to use dry ice to make the kettle appear to blow steam. There were about a half dozen different ideas thrown around about how to make the effect work. Each had their own pros and cons but they were all complicated in some way.

If you use a sound effect, where does it come from? Do you use a recording, played through the sound system? Do you use a discrete speaker, behind the kettle? Does somebody blow a whistle from off-stage? What about dry ice? How do you procure it? How do you use it? Where do you store it? How much will it cost? How do you make the timing right? There are a hundred different solutions to this problem and a hundred different ways for each solution to go wrong.

In the end, somebody finally spoke up: "Why not just boil the water?"

Yes! Get a regular tea kettle. Use an electric hot plate. Put in a certain amount of water that's been measured to boil in a certain amount of time. The actor in the scene just does things the way anybody would do in real life. It took a bit of time and experimentation to figure out how much water to put in the kettle but, in the end, it worked perfectly with little to no fussing around.

After the play was over, the phrase, "Just boil the water" became a common joke around the stage, which meant, "Don't use complicated solutions to solve simple problems when you don't have to."

I like the idea of motorized dampers but manual dampers might be the better solution in the long run. You'll have to think about your situation and how you normally do things then choose the solution that fits your work flow best.

Sometimes, it's better to just boil the water.

[Dave Macaulay]

Doing installations for the rollout, we had a few sites with exhaust blowers serving several projectors. One site installed slide valves at the projector duct fitting for balancing airflow, they worked really well for that. But they could also be used as duct cutoffs. One screen kept the 35mm system (likely unused after digital went in), its exhaust duct could be closed to keep flow up for the new projector and reduce dirt and dust in the 35 lamphouse.

Just search for "8 inch blast gate".

Also, in Hawaii for an Imax installation, same issue as the super humid oceanside air would suck into the chilly lamphouse overnight and steel parts were rusting badly. We installed one and the rusting stopped. That lamphouse had an airflow switch so the operator could not strike the lamp and melt things. But could leave it open at end of day of course.

[Brad Miller]

Randy, the whole "just manually do this or that" methodology may have been fine for theaters that ran film every single day of the week for year after year because it literally becomes "muscle memory" and the projectionists didn't even have to think about it. However for these situations where a theater will only be running film intermittently, mistakes WILL happen on "extra steps" being added to the equation.

Take for example a theater that runs a film show once or twice a month. The projectionist(s) will not be in the same level of daily practice as they were back in say 2005, so "muscle memory" doesn't apply here. If Ryan needs to install some sort of damper on his systems for whatever the reason, it's foolish not to spend just a couple extra bucks and automate it (even if it's nothing more complicated than a relay tied to the projector motor) so a show doesn't get futz'd up because the projectionist is nervous about not messing up his changeovers and forgets about that extra switch here and there that have to be flipped in addition to the regular procedure.

I couldn't care less about the stupid "everything must be manual for it to be a REEL show" fetish. (Yes I wrote "reel" because we all know that pun has been overused by those people to the point of vomiting.) What IS important in the year 2024 is that film shows don't have mistakes in the presentation, or people will start attributing film shows as problematic. It's just like scratching prints in the year 2024. A scratched print no longer becomes something special to seek out. It just helps put film into the grave sooner. In this day and age, each film presentation must be done properly and without ANY mistakes or print damage/wear if film is to survive for much longer.

[Ryan Gallagher]

Thanks for all the further thoughts folks. You are correct in that we currently have no automation on systems other than the ability for doremi to talk to the Christie, AP20, and Bluray player.

I'm not against automation, in fact I hope to add some more soon. Will consider all the options if I get a green light to build a parts list for this effort.

The good news is that projector recovered from it's condensation shower. Had the lamp back in it today, ran it for an hour and redid lamp position/focus and checked current trim. Even made the upgraded glow-in-the-dark frisbee manual insert that will hold us over until we improve things.

I am just glad it was not both projectors, and glad I caught it between screenings. Certainly wasn't the first time, hopefully the last.

[Randy Stankey]

Brad, what I'm saying is that people need to consider what fits their needs in a particular situation.

If I had been directing a Broadway play, we could have spent thousands of dollars to make a teapot appear to boil on stage. We could have had all sorts of special effects and we would have had professional stagehands to operate them. In a college play, we have, maybe a couple-few hundred dollars to spend on the whole show. The stagehands are college students and the rigging is run by a guy we call in from the Local.

If we had been doing this effect or a modern-day movie or TV show, we could have spent a "million" on CGI but we were doing it will college students on a shoestring budget. We had to think about what the students were capable of doing. We had to think about how much time and money it would have taken to engineer the effect. We had to consider whether the actor would be able to pull it off during a show. In the end, we decided that it was better to just boil the water.

In the projection booth, you have to make the same kinds of decisions and decide what's best for the situation. How much is the cost? Who is going to install and operate it? What's going to happen ten years from now when nobody remembers how the thing was hooked up and something needs to be fixed.

Personally, I believe that the simplest solution is usually the best but that doesn't mean that simple is always best.

Maybe it's better to use a hand operated damper and tie a ribbon on the handle that hangs down in the operator's sight when it's in the closed position. I don't know, for sure. You've got to consider what's best for your situation.

[Ryan Gallagher]

Doing installations for the rollout, we had a few sites with exhaust blowers serving several projectors. One site installed slide valves at the projector duct fitting for balancing airflow, they worked really well for that. But they could also be used as duct cutoffs. One screen kept the 35mm system (likely unused after digital went in), its exhaust duct could be closed to keep flow up for the new projector and reduce dirt and dust in the 35 lamphouse.

Those are in fact what we have at the ceiling on the legs that exhaust each spotlight. They ops still have to remember to close them, which they don't always do. They tend to notice when they forgot to open them, as the troopers gets quite hot to operate without gloves.

For sure two more of those would be less hacky than our inserts, and a component of an all manual solution. In conversations today it seems prior hesitations to do anything more "complete" were due to having to modify the rigid stovepipes in place, which are part of the larger existing system above the ceiling. But in my mind nothing an angle grinder or nibbler can't solve. I've at least been promised a "fresh look" at the options. Apparently our booth AC capacity is recently improved to a point this issue is far worse than it has been in the past.

[Brad Miller]

I like the idea of motorized dampers. It's cool but, sometimes, things like that can be a complex solution to a simple problem.

Motorized dampers are not complicated in the least bit. Apply low voltage, they open. Remove low voltage, the spring pulls them closed. It doesn't get much simpler than that.

Brad, what I'm saying is that people need to consider what fits their needs in a particular situation.

Randy, that is literally stating the obvious for just about every decision in life that needs to be made at work, at home, in any industry, etc.

If I had been directing a Broadway play...In the end, we decided that it was better to just boil the water.

Right and I believe I would have gone with the exact same "boil the water" solution had I been a part of that example. However what you are not calculating is that Broadway play would have boiled the water each show, day after day, week after week, show after show. That makes it a useless example in this scenario because that is the opposite of what I wrote. For a theater that's NOT running shows every day on film, manually controlled dampers create extra steps that WILL end up causing show failures and interruptions. This is because it's no longer muscle memory for the projectionist because they aren't running shows every single day on film, unlike your Broadway show boiling water example.

In the projection booth, you have to make the same kinds of decisions and decide what's best for the situation.

Another painfully obvious statement that doesn't actually accomplish anything in the discussion. Let me throw in a bit of sarcasm by stating something else obvious: in the projection booth, the projectionists still need to breathe oxygen when running a show.

What's going to happen ten years from now when nobody remembers how the thing was hooked up and something needs to be fixed.

Anyone operating the projection equipment 10 years from now should be smart enough to figure out how to flip the lever to open the exhaust if something failed to open, but in the meantime at least the equipment lasted 10 years and survived because it wasn't baked or rusted to death due to a damper that a projectionist didn't remember to open or close manually. Plus the theater would still be running film shows because they didn't piss off their audience with botched film presentations where the projectionist forgot the extra manual damper steps. Mistakes like that will only run the patrons off and effectively put an end to shows on film because film shows will become known to the customers as having problems.

Personally, I believe that the simplest solution is usually the best but that doesn't mean that simple is always best.

I agree with your statement in general, but I absolutely disagree that manual levers are better than a simple motorized damper setup. Again, to expect a projectionist who only runs the system occasionally to remember extra steps of manually opening and closing dampers while they are trying to do changeovers on top of everything else they have to do in a manual booth is asking for problems. You are simply discounting the fact that the more infrequent humans do tasks, the more they forget little steps like this. That's my entire point you are clearly missing.

Those are in fact what we have at the ceiling on the legs that exhaust each spotlight. They ops still have to remember to close them, which they don't always do. They tend to notice when they forgot to open them, as the troopers gets quite hot to operate without gloves.

Randy, my point was just proven by Ryan. People forget when they don't operate things every day!

If adding a couple of simple motorized dampers will fix the problem by protecting the equipment from humidity down the exhaust stack or overheating due to no airflow AND will help ensure that film presentations run smoothly...I find it absurd someone would opt for a manual lever with all of the mistakes that can occur as a "solution" to the problem.

Remember, apply low voltage, they open. Remove low voltage, the spring pulls them closed. That's pretty damn simple.