The following table is a guide to determine the hot water demand for commercial or
light industrial facilities.
DEVICE LOCATION WATER CONSUMED AT 60'C(LITRES) Shower Aged Homes 18 - per person Domestic Dwellings 15 - per person Caravan Parks 18 - per person Hotels/Motels 18 - per person Mining Towns 25 - per person Baths Domestic & Hotels 60 - per person per day Wash Basins Domestic Dwellings 2 - per person per day Offices 1 - per person per day Dish Washing Sinks Domestic Dwellings 7 - per sink full Hotel/Motel 10 - per sink full Dish Washers Domestic Dwellings 10 - per meal Hotel/Motel 90 - per hour One Meal Sitting 2 'hour' Operation Two Meal Sitting 4 'hour' Operation Glass Washers Hotel Bars Weekdays 3 hours use/day 55 - per hour per unit Weekends 5-6 hours use/day Restaurants 6 - 10 per hot meal Messes (Mining) 75'C required 10 - per meal Full Laundry 27 - per person per day Blocks (Mining) Ring Main Losses Good condition - Small +(10%) of Total Demand Good condition - Large +(20%) of Total Demand Long or Poorly Insulated +(50%) of Total Demand
4.2 GENERAL NOTES
As some dish washers have their own water heating system, not all dish washers will require inclusion with the hot water demand calculations. The types to be used on the installation should be checked prior to calculating the hot water demand. Use manufacturers' recommendations wherever possible when considering the actual hot water usage of the dish washer.
When the project is to add a Non Residential Solar Hot Water System to an existing installation it is preferable to install a water meter in the existing system and accurately measure the hot water demand over a 2 or 3 month representative period. This method will ensure that the actual demand is known and can also provide hard facts to present to the customer during the selling process.
When connecting a Non Residential Solar Hot Water System to an existing hot water system, care should be taken to ensure that energy is not wasted.
The following points require particular attention:
i) Existing hot water pipe work insulation should be checked and up-graded where necessary.
ii) Heat loss up hot flow pipes and into header tanks should be checked and heat traps fitted where appropriate.
iii) When connecting into an existing oil or gas fired hot water boiler, care should be taken to ensure that the low operating efficiency of the boiler does not adversely affect the whole system.
Use by-pass valves to isolate the existing boiler during the summer months so that during these periods the boiler can be isolated from the circuit.
Low efficiency boilers can be deleted in favour of gas boosted Non Residential Solar Hot Water Systems.
iv) It is preferable to install several systems, strategically placed around the building or groups of buildings to avoid long ring main circuits. For low usage areas not economically connectable or economically suitable to the central Heat Store system, install standard Solahart roof top Residential Solar Hot Water systems.