Domestic hot-water systems supplies taps in houses or buildings with hot water.
Output Heating Capacity
Output heating capacity of a domestic hot-water system:
hout = q ρ dt cp (1)
hout = heating capacity, output (Btu/h)
q = flow rate (gph)
ρ = 8.34 - density of water (lbs/gal)
dt = temperature rise (oF)
cp = 1.0 - specific heat of water (Btu/lboF)
Input Heating Capacity
Input heating capacity of a domestic hot-water system:
hin = q ρ dt cp / μ (2)
hin = heating capacity, input (Btu/h)
μ = efficiency
Recovery rate for an electrical heater in a domestic hot water system:
RR = hin μ / dtρ
= P (3413 Btu/kW) / dtρ (3)
RR = recovery rate (gal/h)
P = electrical power supplied by heater (kW)
Temperature rise in an electrical heater in a domestic hot-water system:
dt = hinμ / qρ
= P (3413 Btu/kW) / qρ (4)
Electrical Power Supply
Electrical power supply to a domestic hot-water systems:
P = q ρ dt cp / (3413 Btu/kW) (5)
Hot and cold water service systems - design properties, capacities, sizing and more.
Introduction to general design of domestic service water supply systems - with pressurized or gravity tanks.
Content of hot water in some common used fixtures - basins, sinks and baths.
Hot water can be circulated through a return pipe if it's instantly required at the fixtures.
Consumption of hot water per person or occupant.
Dimensions and capacities of hot-water storage tanks.
Hot water consumption of some common equipment as basins, sinks, baths and showers.
Activity and average water consumption
Free online tool for designing water supply systems in buildings.