Plumbing Engineering-5

Calculation of Hot water amount which required for different buildings:
1- From Table (6) we determine the type of building and the type of sanitary equipment.

2- Find the total demand for every type of fixture
Total demand for every type of fixture= demand for every type of fixture (From Table 6) * No. of the fixture

3-Find total hot water demand for the system
Total Hot water demand for the system = sum of Total demand for every type of fixture
4- Find Max. Hourly demand for system and this represented minimum heater capacity


Max. Hourly demand for the system= Total demand for the system* Demand factor (From Table 6)

5- Calculate the storage tank capacity which depends on the type of building.

Storage tank capacity = Max. hourly demand for the system* storage capacity factor (From Table 6)













Example:- Determine heater and storage tank size for an apartment building for a number of fixtures :
60 lavatories
30 bathtubs
30 showers
60 kitchen sinks
15 laundry tubs

Solution:-
Hot water demand gal/hr Flow per fixture gal/hr ( from table 6) Number of fixtures Type of fixtures
120 2 60 lavatories
600 20 30 bathtubs
900 30 30 showers
600 10 60 kitchen sink
300 20 15 laundry tubs
2520 Total demand for the system


Max. hourly demand for system=Total demand for the system* Demand factor
From Table (6) Demand factor=0.30
Max. hourly demand for system= 2520 *0.30 = 756 gal/hr
minimum heater capacity=756 gal/hr
Storage tank capacity = Max. hourly demand for system* storage capacity factor
from table (6) storage capacity factor = 1.25
Storage tank capacity = 756 * 1.25 = 945 gal