Document Jv86jmoKy19LOEQEzN7MZZ4jr

160 CHAPTER 11 1960 Guide and R. R. Tucker: ASHVE Research Repost No. 874--Carbon monoxide concentration in garages (ASHVE TaANRAcnoNs, Vol. 36, 1890, p. 511). F. C. Houghten and Paul McDermott: ASHVE Research Repost No. 936--Carbon monoxide distri bution in relation to the ventilation of an underground ramp garage (ASHVE Transactions, VoL 38, 1932, p. 439). F. C. Houghten and Paul McDermott: ASHVE Research Report No. 934--Carbon monoxide distrifeuticn is relation to the ven tilation of a one-floor garage (ASHVE Transactions, Vol. 38, 1932, p. 424). F. C. Houghten and Paul McDermott: ASHVE Research Report No. 967---Carbon monoxide distribution in relation to the heating and ventilation of a one-floor garage (ASHVE Transactions, VoL 39,1933, p. 395). A. H. Situs, E. K. Campbell, and L. M. Farber: Carbon monoxide surveys of two garages (ASHVE Transactions, Vol. 40, 1934, p. 263). BIBLIOGRAPHY J. B. Dick: Experimental Studies in Natural Ventilation of Houses (Department of Scientific and Industrial Research, Building Research Station Note No. 180, Garston, Watford, England). |- J. B. Dick: Measurement of ventilation using tracer gas technique (ASHVE Journal Section, Heating, Piping and Air Conditioning,'May i950, p. 131). C. W. Coblentz and P. R. Achenbach: Design and per formance of a portable infiltration meter (ASHAE Transac tions, Vol. 63, 1957, p. 477). Gorofl* wnft'fefioa R. R. Sayers, A. C. Fieldner, W. P. Yant, and B. G. Thomas: Experimental Studies on the Effect of Ethyl Gasoline and Its Combustion Products ((/. S. Bureau of Mines Monograph No. 2, 1927). A. C. Fieldner, Yandell Henderson, J. W. Paul, K. R. Sayers, et al: Ventilation of. vehicular tunnels (ASHVE Journal, January-December 1926). S, H. Ash and L. L. Naus: Use of Diesel Engines m Tunnels (U. S. Bureau of Mines Information Circular No. 7222, 1942). L. B. Berger: Ventilation Involved in the Use of Gasoline Powered Equipment in Enclosed Spaces (/. S. Bureau of Mines Information Circular No. 7404, 1947). J, C. Holts, L. B. Berger, M. A. Elliott, and H. H. Schrenk: Diesel Engines Underground: Composition of Exhaust Gas from Engines in Proper Mechanical Condition (U. S. Bureau of Mines Report of Investigations No. 3608, 1940). L. B. Berger, M. A. Elliott, J. C. Holts, and H. H. Schrenk: Diesel Engines Underground: Use of Diesel Locomotives in Construction of the Delaware Aqueduct: Effect of Exhaust Gases upon Quality of Tunnel Air (U. S. Bureau of Mines Report of Investigations No. 4032, 1947). CHAPTER 12 HEATING LOAD General Procedure, Design Outdoor Weather Conditions, Indoor Temperatures, Attic Temperatures, Temperatures in Uryheated Spaces, Ground Temperatures, Basemen) femperafures and Heat Loss, Heat losses from floor Slabs, Transmission Heat loss. Infiltration Heat Loss, Selection of Wind Speeds, Auxiliary Heat Sources, Intermittently Heated Buildings, Residence Heal loss Problems PRIOR to designing a heating system, an estimate must be made of the maximum probable heat loss of each unit. If mechanical exhaust from the room is provided, in amount equal to the outdoor air drawn in by tbe unit, the natural infiltration losses must also be provided for by the unit. room or space to be heated, based on maintaining a selected-If no mechanical exhaust is used, and the outdoor air supply Indoor air temperature during periods of design outdoor weather conditions. The heat losses may be divided into two groups, namely: (1) the transmission loses or heat trans mitted through the confining walls, floor, ceiling, glass, or equals or exceeds the amount of natural infiltration that would occur without ventilation, the natural infiltration may be neg lected. 9. The sum of the heat losses due to transmission (Item 6) through the outside walls and glass, as well as through any cold other surfaces; and (2) the infiltration losses or heat required to warm outdoor air which leaks in through cracks and crevices, around doors and windows, or through open doors and windows, or heat required to warm outdoor air used for floors, ceilings, or roof, plus the heat equivalent (Item 7) of the cold air entering by infiltration, or required to replace mechani cal exhaust, represents the total heat loss equivalent for any building. 10. In buildings that have a reasonably steady internal heat ventilation. release of appreciable magnitude from sources other than the heating system, a computation of this beat release under design - GENERAL PROCBMJRE The general procedure for calculating heat losses of a conditions should be made for deduction from the total of the heat losses computed in Items 1-9. This is especially important for heating systems of high initial cost or those for which a de mand charge is based on installed capacity. structure is: DESIGN OUTDOOR WEATHER CONDITIONS 1. Select the design outdoor weather conditions: tempera ture, wind direction, and wind speed. The data on climatic oonditioas'given in Tables 1 and 2 will be helpful, but should be The ideal solution to the basic problem which confronts the designer of a hearing system is to design a plant that has a used with judgment as suggested in the section Design Outdoor Weather Conditions. 2. Select the indoor air temperature that is to be maintained in each room during the coldest weather. (See Table 3.) 3. Estimate temperatures in adjacent unhealed spaces and capacity at maximum output just equal to the heating load which develops when the most severe weather conditions for the locality occur. In most cases, economics interferes with the attainment of the attic. (See section Attic Temperatures.) The attic tempera this ideal. Studies of weather records show that the most ture need not be estimated if the combined roof and ceiling co efficient is used. 4. Select or compute the heat transmission coefficients for outride walls and glass; also for inside wails, floors, or top- severe weather conditions do not repeat themselves every year. If heating systems were designed with adequate capacity for the maximum weather conditions on record, there would floor ceilings, if these are next' to unhealed space; include roof if next to heated space. (See Chapter 9. If the design wind speed is appreciably different from 15 mph, the appropriate change in the heat transmission coefficients in Tables 5 to 15 of Chapter 9 can be found in Table 20 of that chapter.) be considerable excess capacity during most of the operating life of the system. The weather records of principal cities of the United States1 have been analyzed to determine the probability of occur 5. Determine net area of outside wall, glass, and roof next rence of certain low temperatures. The results of this analy to heated spaces, as well as any cold walls, floors, or ceilings not to unheated space. Such* measurements are made from building plans, or from the actual building, ijng inside dimensions. 6. Compute the heat transmission losses for each kind of wall, sis appear in Table 1. Data for Canadian cities obtained by a different analytical method appear in Table 2. Five probabilities of outdoor temperatures are offered for glass, floor, ceiling, and roof in the building by multiplying the American cities and four for Canadian cities. The analytical , beat transmission coefficient in each case by the area of the surface in square feet, and the temperature difference between the indoor and outdoor air. (See Items 1, 2, and 3.) 7. Select unit values and compute the heat equivalent of the methods used for determining the several design temperatures ' died in Table 1 for U. S. and Table 2 for Canadian cities are described in the footnotes of the tables. infiltration of cold air taking place around outside doors and windows. These unit values depend on the kind or width of crack, wind speed, and the temperature difference between the indoor and outdoor air; the result expreses the heat required to warm up the cold air leaking into the building per hour. (See Chapter/11.) 8. When positive ventilation using - outdoor atr is provided by an air-heating or an air-conditioning unit (see Table 1 of Chapter 6, Table 3 of Chapter 13, and air quantities given in Chapter 48 for various conveyances), the heat required to warm In many eases, occasional failure of a heating plant to maintain a pre-selected indoor design temperature during brief periods of severe weather is not criric&L However, the successful completion of some industrial or commercial proc esses may depend upon close regulation of indoor tempera tures. These are special cases and require extra study before assigning design temperatures. Before selecting an outdoor design temperature from the outdoor air to room temperature must be provided by the (Text continued on p. 165) 161