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1948-49 Theatre Catalog, 7th Edition, Page 177 (166)

1948-49 Theatre Catalog, 7th Edition
1948-49 Theatre Catalog
1948-49 Theatre Catalog, 7th Edition, Page 177
Page 177

1948-49 Theatre Catalog, 7th Edition, Page 177

overtime which will be required if the theatre is to remain open during the progress of the installation. It is possible to allow much of the work required for an air-conditioning system or ventilation system to proceed during show time, but for reasons which are very obvious, the work over the main ceiling should be done only when the public is not subject to injury or panic.

In instances where there is no space in the attic for ducts, then the problem of distributing the air properly in the auditorium becomes more difficult, but not impossible. The large ducts can sometimes be run over the top of the roof, in which case they must be well insulated. In other cases the ducts can be installed to imitate beams through the center and directly under the ceiling, or along the sidewalls.

In the other parts of the house, where the duct sizes are much smaller waste spaces can be found, or the ducts furred in so that they do not detract from the general appearance.

Cleaning Ducts and Plenums

If any or all of the existing sheet metal ductwork is to remain after the remodeling, then arrangements should be made to have the interiors of the ducts thoroughly cleaned of the accumulated dust and dirt. In the larger cities, some contractors specialize in this

class of work, and do a very excellent.

job of cleaning with special vacuum cleaning equipment. To accomplish this, it is necessary to cut holes in the ducts at intervals, and these should of course be closed up air-tight after the job is finished.

While this job is being done the entire duct system should be gone over and all joints and seams which may have opened should be tightly closed, and any hangers which may have become loosened or removed should be repaired. Particular attention should be given at the points where the sheet metal ducts join with plaster or masonry ducts which are sometimes used for vertical risers.

The same cleaning operation together with the closing up of all leaks as required for the ducts should also be carried out for any plenum spaces to which the ducts are connected. The space between the balcony soffit or that of the mezzanine and the construction above is very often used for this purpose, and the duct connections to such spaces, also all the enclosing construction should be made as tight as possible, and of course, should also be cleaned thoroughly. Many times this will mean the difference between the satisfactory and unsatisfactory operation of this portion of the ventilating or conditioning system. After the ducts and plenums have been cleaned and made tight, periodic inspections should be given and necessary steps taken to see that they remainain this condition.


If dust and dirt are found to gather in the space with undue rapidity, either a new bank of filters should be installed, or the system inspected for leaks, and these, if any are found, closed.

Many ventilation systems will be found where no filters have been pro

vided. If this equipment is installed in an adequate manner the cost of cleaning the interior of the house will be noticeably reduced. The cheapest installation for this purpose employs throw-away filter units made of glass fibers, animal hair, etc., and are very satisfactory if inspected regularly and replaced when required. Automatic selfcleaning equipment which is available at a higher original cost produces far better results.

Insulation of Ducts

While the duct system is being inspected for leaks, etc., evidence of rusting of the metal may also be noticed. This condition will indicate that excessive condensation is taking place because of the difference in temperature of the air in the duct and the temperature of the air in the enclosing space. This condition is often found where the main supply ducts run over the suspended ceiling, and the attic space becomes very hot due to the lack of roof insulation, and proper ventilation of the attic space itself. Gravity ventilators through the roof into this space, with louvers in the exterior walls at each corner, will provide circulation and relieve the condition to a great extent. It may, however, be necessary, in addition, to insulate the ducts themselves, which will not only stop the condensation, but will also take a large load off the air conditioning plant. The louvers referred to above together with the gravity ventilators should be provided with weather-tight closures for the winter season. ,

If new roofing is to be installed, then it is recommended that the necessary insulation be installed on the roof deck before the new roofing is laid. This will in most cases dispense with the neces sity of insulating the ducts themselves, but the gravity ventilation is recommended in either case.

Spraying the Roof

When the water from the condensing unit of the air conditioning system is not recirculated through the system, the installation of the necessary piping and pump to spray this water over the roof area, will produce a certain amount of evaporative cooling and keep the space underneath the roof many degrees cooler, a distinct help to the air-conditioning system. This practice, of course, is not recommended if cost of water is high. Then, economical considerations enter the picture and a cooling tower, evaporative condensor, or spray pond is indicated to recover the water for re-use in the condensors.

If a spray system is installed on the roof, it will be necessary to be sure that the roofing is in good state of repair, with special attention to the gutters, flashings, and down spouts or leaders, so that no leaks will develop from the constant presence of water on this area.


If the contractor proposes the locating of fans or other heavy equipment in any part of the stucture, other than the basement, the structural supports should be checked by a competent engineer, and the contractor required to install any

additional supports or reinforcing that may be necessary to carry the additional imposed load. Special care regarding this procedure should be taken in cases where equipment is to be installed on the roof.

The location of the fans and compressors is very important because of possible noises and vibrations which may be very annoying to the audience. This equipment should be set on heavy concrete bases, and equipped with vibration eliminators. The outlet velocity of the large supply fan should be low, so that no sound of rushing air will result. Sometimes the gas piping from the compressor to the condenser will be attached to, or supported by, a structural member of the building. Such a situation will often cause annoying noises in the theatre, which can only be overcome by removing the support or connection, or by proper insulation of these members.

Fresh Air Intake

The fresh air intake should be so located that no excess amount of dirt, smoke from fiues on adjoining buildings, or other undesirable odors will be drawn into the ventilating system. To so 10cate the fresh air intake is sometimes very difficult and expensive, and as a result many intakes are installed in exit courts or alleys, close to the ground, or alongside of a flue from an adjoining restaurant. Such installations will always he a source of annoyance and complaints and will eventually have to be changed.

Consideration should also be given to the location of the exhaust vents from the system, as it. is possible to locate these where they would be a nuisance to the adjoining porperty owners.

Location of Equipment

If the air-conditioning equipment is to be installed within the existing confines of the theatre, there is a possibility that the space assigned may be too small, with the result, that it will be very difficult and expensive to service this equipment or to remove and replace certain parts which will surely wear out during the life of the equipment. If different parts of the machines are too difficult to get at, these will be neglected with the resulting repair expense.

If no adequate space is available in the existing structure the cost of building an addition or a pent house will be returned many times during the expected life of the equipment.


No attempt should be made In skimp on the qualin of elorlrir wiring in the Ihealre building. Cheap installations may result in the unIimvly deslrurlion of an, otherwise substantial amusement center. Only an unwise owner would make Ihv (le('isiun of being penny-wise and pound-foolish. If the electric wiring job is done righl and under expert guidance, polonlial fire hazards can be reduced and Ihe harm caused by faully wiring eliminaled.

1948-49 Theatre Catalog, 7th Edition, Page 177