Our building has been said to be the last of the "Tinseltown" design. It was built in 1996, just before they switched to the "stadium" design. In fact, they say our building was almost going to be stadium until they changed their minds at the last minute... Anyway, here's the problem:

Every morning when you go in to open up you find all the platters and the tops of the lamphouses covered with dust bunnies. It seems that when the air conditioning kicks-on in the morning the "surge" of air blows all the crap out of the ducts and out into the room. Of course, somebody had the bright idea to put all the vents right above the projectors!

Sometimes it hapens during the day, too. Especially if it's hot outside and the AC cycles on and off a lot. (It only happens diring the summer when the AC runs -- Not when the burners run for heat.)

I'm not entirely sure which duct it's comming from. It might be the ventillation ducts or it might be the air-return ("balancer") ducts.

Of course, having dust bunnies attacking our film isn't a good thing. Especially since we've worked so hard in the last year to clean up our presentation. It feels like one step forward and two steps back, sometimes!

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Has your theater got electronic air cleaners instead of regular air filters installed in the HVAC system?

When they are turned off, the minute particles that collect on the charged surfaces are released and in some systems the particles fall into the ducts. The next time the blower starts....

If no EAC system, how often are the air filters changed? I've seen many commercial set-ups that have had the same filters in them for months, and are clogged. Also, who supplies the filters? Your theatre or the service co? If you can see through the new filters, just think how much crud gets thru them. I look for filters that are thick. They cost more, but are worth it.

I have an EAC on my home HVAC system that had problems blowing white dust all over everything. I installed the filters just past the EAC and stopped all dust. All I have to do is vacuum the filter surface every couple of months and they last forever, well, a year or more anyway.

Honeywell Air Systems RULE!

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

I wish I had a nickle for evey stupid architect mistake, like vents directly over the film, or (my fav) return ducts behind the screen so dirt get drawn into the holes.

In "clean-rooms" for IC wafer maufacturing, they find that (after filtering the incomming air) the next problem is dust from people's clothing. The doors to clean-rooms have an "air-wash," where a big blower blasts you (while in a sort of air-lock) before you go in.

If an even "cleaner" room is needed, that's when they make you wear the "bunny-suits."

Cleanroom technology is essential to the manufacture of microelectronic components and photographic film. Kodak's film and microelectronic manufacturing areas have air-jet/vacuum "people washers" and require "bunny suits" (cleanroom coveralls for shoes, clothing, hair and beards) to enter.

Such extreme measures are usually not needed for projection rooms. Easily cleaned worksurfaces, good air filtration and good housekeeping are usually all that is needed to maintain clean film images. On-line film cleaners are recommended to remove any dirt picked up during projection.

The most important "rule" is not to let the film or leader come in contact with a dirty surface. Operators who say "it's only leader" or "I don't have time to wipe off the rewind bench" are usually the ones with the dirty prints.

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

I'm not sure it's the intake filter. I just think the ducts are dirty. Since it only happens when the AC is on, maybe it's the condenser coil?

The HVAC units we have are Trane. We have Novar control system. All I can say is "Nothing runs like a Trane". -- "Clickety Clack! Clickety Clack!". As far as "Novar", take of the "r" and it's "No va" -- Spanish for "Doesn't Go."

You might check, if possible, to see if all the filters are installed correctly. There is an arrow pointing which way the air is supposed to flow through them. It does make a difference!

Trane stuff is good. GE made the compressor that they used to hawk as being indestructable (Remember the Weathertron® heat-pumps of the early '80's? Same compressor, and they are still running.)
Most heat-pumps last around 10-12 years before the compressor dies. GE no longer owns the compressor design, or has leased it to Trane and they now build it themselves.

I have installed several roof-top package systems over the years, but no theatre jobs. I always hoped that I could do that just once!

It would be a good idea to install filter material over the supply ducts in the booth. They can be changed every month or so when they get dirty. Unfortunately, the duct system is probably caked with grey dust by now. Changing to better filters will fix the problem, but, all the crud that is in the ductwork will have to work its way out.

Oh, yeah. I just meant I thought using a few simplified ideas might work. The three big things I wanted to do was; a tight seal around the port windows for noise and dirt; ceiling tiles that don't 'rain' little fibers down, and a filtered closed-loop for the lamphouses. So much air gets sucked in by the snood that the whole area there (the gate, trap, intermittent) gets pretty dirty. I wasn't thinking about 'sticky-floors', etc.

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I agree with your suggestion to have the ducts professionally cleaned if they have a buildup of debris. Even new ductwork often has alot of construction "crud" left in them. Once the ducts are cleaned, be meticulous in changing the filters properly and frequently.

Another worthwhile idea to improve booth cleanliness is to have a central vacuum cleaning system installed, exhausted to the outside. Using a shop vac, broom, or dry mop just tends to stir up the dirt, so it lands elsewhere. Wet-mopping works well if you're on a budget.

The guy who thought of using blowers to clean the auditorium should be made to clean out each perforation in the screen with a toothpick, one hole at a time! The dust raised by the blowers also finds it's way onto the port glass, and even into the booth. I recall another thread mentioned watching the placement of the HVAC ducts so they don't suck or blow dirty air through the perforated screen.