Hot water requirements
For a residential building, hot water may be supplied to all plumbing fixtures and equipment used for bathing, washing, cleansing, laundry and clunary purposes. For a nonresidential building, hot water may be supplied for bathing and washing purposes.
the design of a hot water supply may be based upon the following temperature requirements:
1. Scalding ---- 68 deg. Centigrade
2. Hot bath ---- 41 deg. Centigrade
3. Warm bath ---- 37 deg. Centigrade
4. Tepid bath ---- 30 deg. Centigrade
5. Sink ---- 60 deg. Centigrade
The capacity of hot water vessel shall be based on the maximum short time demand of the premises.
Cold water supply connection to the water heaters
The connection of cold water supply piping into water heater shall be made near its bottom. The minimum size of cold water supply piping shall be based on the probable hot water demand of different fixtures but not less than 25 mm. The supply pipe shall deliver cold water into hot water cylinder as follows:
1. The water heater( electric or gas ) of less than 15 litres storage capacity may be directly connected to the water main through a nonreturn valve.
2. The storage heater of 20 to 70 litres capacity may be connected directly to the water main through a nonreturn valve and with an additional device that will prevent the siphonage of hot water back the water main.
3. The enclosed water heater with storage capacity greater than 70 litres shall be fed from the storage tank. This water heater shall not be connected directly to the water main.
4. The water supply connection to an open vessel type water heater may be made with an air gap of at least 15 mm above the top edge of the water heater. Ball valve connection shall not be used to control the flow of water into this water heater.