Film-Tech Forum ARCHIVE: Theatre Temperature

This is topic Theatre Temperature in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by William Leland III (Member # 1400) on 03-22-2003, 04:12 PM:

I was wondering if anyone has put a thermostat on the outside of the booth window?

It would be very convenient and save time. In most booths I have worked, projectionist control the temperature. So why not have a thermostat stat on the outside of the booth window. When we would start a movie, we could check the temperature, rather than do a temperature walk threw.

not sure about what forum to put this in. sorry

Posted by Aaron Mehocic (Member # 15) on 03-22-2003, 05:54 PM:

Impractical given that heat rises. If the port is located near the ceiling of the auditorium, the temperature outside will not be the same as the floor level.

Posted by William Leland III (Member # 1400) on 03-22-2003, 06:11 PM:

yeah i thought of that also, but stadium seating style booths are only a few feet higher than the last row of seats. you could also have the thermostat at the bottom and have the readout displayed at the booth window.

Posted by Aaron Mehocic (Member # 15) on 03-22-2003, 06:16 PM:

True about stadium, and I wasn't thinking about the possibility of remote sensing. I like climate control located in the booth because it does save a lot of hassles with customers and dumb-ass staff members alike. I guess the age old problem of too hot / too cold keeps rearing it's ugly head once again.

Posted by John Hawkinson (Member # 1135) on 03-22-2003, 06:28 PM:

Even if you have stadium seating, if you have an HVAC system,
all air should be flowing and the temperature near the booth
window shouldn't that far off from the rest of the room. Imagine
you're measuring the return air temperature and not the room temp. or the supply temp.

--jhawk

Posted by Chris Byrne (Member # 1563) on 03-22-2003, 08:00 PM:

William,

Like most of our Australian sites, we have gone to a centrally controlled air conditioning system, with DDC, modem, etc.

I think that although the system is obviously designed for greater cost efficiency - the old thermometer set-up worked fine.

I find that there are just as many complaints now as there was with the old set-up, which just proves the fact that you can't please everybody.

Also if you get on OK with your a/c contractors, ask if you can borrow a 'sling' to test the relative humidity inside the booth.
Outside humidity regularly tops 90% outside where I live and I found I had to drop the booth temperature a couple of degrees to get anywhere near the optimum 50 - 60% range of realtive humidity.

Posted by William Leland III (Member # 1400) on 03-22-2003, 09:20 PM:

Chris, I work at the Charleston IMAX and our booth has a De-Humidity control.

In Charleston,S.C we have a 90% humidity in the summer time or higher. I can relate to your problems with keeping the humidity in the 50 - 60% range. Right now it is at 49.

Posted by Aaron Mehocic (Member # 15) on 03-22-2003, 09:46 PM:

William,
So you have a de-humidifier, do you also have a humidifier for say, December or January. Here in Pennsylvania my booth is running anywhere from 30% - 40% RH during those months. I know thats a little on the low side, but I'm aprehensive to start up any humidifiers because I don't want to corrode any circuitry by adding excess moisture into the air.

Also, maybe John Hawkinson could help here, I know you can get humidifiers for home furnace units, but what about HVAC units ( I apologize, since I don't know much about the mechanics behind HVAC).

One last point about 60% RH as being the high end of the optimum range: Everytime my hygrometer is pushing that percentage, I've got bulges on these prints like you wont belive, and I'm being extra vigil for brainwraps because I know there coming. [Frown]

Posted by John Hawkinson (Member # 1135) on 03-22-2003, 10:38 PM:

Sorry, Aaron, out of my depth.

--jhawk

Posted by Gordon McLeod (Member # 33) on 03-22-2003, 10:58 PM:

I would dream of having our booth as high as 49% most of the time it is 22 or less [Mad]

Posted by Aaron Mehocic (Member # 15) on 03-22-2003, 11:02 PM:

Gordon,
How about in the summer? Your only 150 miles due north of me.

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-22-2003, 11:21 PM:

In the summer when I'm another 100 miles due north of Gord I have a hell of a time keeping 50%RH due to the booth air conditioning. The hotter (and more humid) it gets outside the harder it is to keep the humidity up in the booth.

At the same time, some of the other theatres I work at (with little for air conditioning) have no problem keeping 100%RH. [Frown]

The 110 degree booth temperatures aren't great either.

The rest of the year it's a losing battle no matter what we do.

Posted by Paul G. Thompson (Member # 655) on 03-23-2003, 12:49 AM:

We have one of our theatres enviromently controlled by the HVAC system, and we keep the auditorium and booth temperatures about 70 to 72. I don't know what the RH is, but it must be ok. We never had anyone complain about uncomfortable temperatures in the auditoriums. And I have not seen any adverse effects of excessive or not enough humidity in the booth.

Of course, we don't have the extreme temperature swings that other locations have, so maybe that has something to do with it.

Posted by Rick Stowell (Member # 1624) on 03-23-2003, 09:13 AM:

To William's original question: We have sensors in each auditorium between the front row and the screen. The actual thermostat and the readout are in the booth.

We have a minimum of 2 degrees range, so we've learned over the years to set them at 71 to 73 degrees, winter or summer.

Question: When we built 9 years ago, we were told that sound travels through the ducts, so each auditorium has a separate HVAC unit, as well as the lobby. Is this accurate information?

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-23-2003, 04:47 PM:

quote:
When we built 9 years ago, we were told that sound travels through the ducts, so each auditorium has a separate HVAC unit, as well as the lobby. Is this accurate information?

Sound sure can travel between theatres through ductwork.

Posted by John Pytlak (Member # 331) on 03-23-2003, 08:03 PM:

The ideal range for film projection and handling is between 50 and 60 percent RH. Really low humidity will cause excessive "positive" curl and increased static charging. Very high humidity will cause "negative" curl, and the moisture softens the gelatin emulsion, making it stickier and more likely to be abraded. High humidity is also likely to cause rust and corrosion of equipment.

Posted by Gordon McLeod (Member # 33) on 03-23-2003, 08:21 PM:

Considering that cinesphere sits in lake ontario one would think low humidity would not be an issue but even in the summer it is lucky to get the booth up to 40%

Posted by William Leland III (Member # 1400) on 03-24-2003, 10:25 AM:

Aaron Mehocic, during the winter months our humidiy reading was in the low 20's. We do have a humidifier and I saw no help. The film would still stick. I am assuming your are running 35mm film? I have never found a way not to keep a print from sticking once the humidity is out of the control area. Film Guard does help.

Mr.Pytlak what do you mean by an "excessive positive curl" do you mean the film will actually curl? During the winter months our film was concaving. It ran fine but from the QTRU to the projector the film was "curving" down towards the floor. Is this what you are referring to as "excessive positive curl" .?

Posted by John Pytlak (Member # 331) on 03-24-2003, 01:26 PM:

Yes. With very low humidity, the gelatin emulsion loses moisture and shrinks relative to the polyester base, so it pulls in and causes "positive" curl. With very high humidity, it expands with the added moisture, and curls the other way -- "negative curl". It's all described on the Kodak website:

http://www.kodak.com/country/US/en/motion/support/h1/baseP.shtml

A quick way to judge the proper humidity is to hang up a short strip of film --- it should hang with just a slight amount of "positive curl". If the curl of the film is more than a few millimetres across the 70mm width, use a humidifier to get to the ideal range of 50 to 60 percent RH.

Posted by Aaron Mehocic (Member # 15) on 03-24-2003, 02:10 PM:

William,
Yes, I'm running 35 mm. Not all humidifiers are created equal. Sears Kenmore builds about the best I've seen and I hardly ever use it for already mentioned reasons. NEVER NEVER NEVER use a humidifier that sprays water directly into the air (I know you know that, but for the popcorn poppers out there that might just care enough to visit this site.)

Posted by William Leland III (Member # 1400) on 03-24-2003, 02:33 PM:

Mr.Pytlak thanks, that site is very helpful.

Posted by John Pytlak (Member # 331) on 03-24-2003, 02:37 PM:

The most efficient humidifiers blow air through a foam, paper, or ceramic material that is saturated with water, and the water evaporates into the air. They are sometimes called "whole house" humidifiers, or "Wick, evaporative" humidifiers:

http://home.howstuffworks.com/humidifier4.htm

http://home.howstuffworks.com/humidifier1.htm

Steam vaporizers actually boil the water to form steam, which uses alot of electricity. The hot steam can also cause burns.

Ultrasonic or impeller humidifiers that actually spray or mist the water into the air are NOT recommended. The mist may actually get things it touches wet (not good for film or electronics), and carries all the minerals that were in the water, so that when it evaporates, it will leave behind mineral deposits (also not good for film or electronics). Do NOT use a "cold mist" impeller or ultrasonic humidifier in a projection room.

Here is an example of an evaporative "whole house" humidifier:

http://www.allergybuyersclubshopping.com/bemis-h12-300.html

Posted by Lance C. McFetridge (Member # 95) on 03-25-2003, 10:23 AM:

Each of my auditoriums has a remote reader that samples the temperature at about 6' off of the lowest floor height. This remote sends the temp to the thermostat located in the booth. We find that 74 in the winter and summer is just right for comfort. Each auditorium has it's own HVAC rooftop unit.
I also put a remote in the lobby with the thermostat in the storage area so no one messes with it.
lance

Posted by William Leland III (Member # 1400) on 03-25-2003, 03:45 PM:

Lance, what type of remote reader do you have? Who makes it? Was it installed by the builders or was an after thought? Does it work well? Thanks Will

Posted by Lance C. McFetridge (Member # 95) on 03-25-2003, 06:36 PM:

Will,
Both the thermostats and remotes are manufactured by Trane.
I have had them in from day one and they do work well. You can calibrate them if needed and are simply attached through a low voltage thermostat wire. I will check for the model number tomorrow. Hope this helps,
lance