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QVS Electrical Supplies | Electrical Wholesale
 Water Heating
 |
Water Heating |
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Untitled Document
Storage recovery time |
Approximate time in minutes to heat 10oC to 65oC |
| Ltrs. |
Loading in Kw |
| |
2 |
3 |
4 |
5 |
6 |
7 |
12 |
18 |
| 5 |
10 |
6 |
5 |
4 |
3 |
3 |
2 |
1 |
| 10 |
19 |
13 |
10 |
8 |
6 |
5 |
3 |
2 |
| 15 |
29 |
19 |
14 |
12 |
10 |
8 |
5 |
3 |
| 50 |
96 |
64 |
48 |
38 |
32 |
27 |
16 |
11 |
| 100 |
192 |
128 |
96 |
77 |
64 |
55 |
32 |
21 |
| 200 |
384 |
256 |
192 |
154 |
128 |
110 |
64 |
43 |
| 300 |
577 |
384 |
288 |
231 |
192 |
165 |
96 |
64 |
| 400 |
769 |
513 |
385 |
308 |
256 |
220 |
128 |
85 |
| 600 |
1153 |
769 |
577 |
461 |
385 |
330 |
192 |
128 |
| 1000 |
1923 |
1282 |
962 |
769 |
641 |
549 |
320 |
214 |
| |
Time in minutes |
|
Guidelines for usage of hot water |
Average Hot Water Requirements |
| Application |
Demand in litres |
Temperature oC |
| Hand wash |
1 |
37 |
| Basin fill |
5 |
37 |
| Sink fill |
10 |
50 |
| Shower |
20 - 50 |
37 |
| Bath |
80 - 120 |
40 |
| Comm. sink |
25 |
50 |
| Cup: tea/coffee |
0.2 |
100 |
|
Schematic SHW,SB |
|
1. Isolating valve
2. Combined control valve
(SHW only)
3. Line strainer
4. Pressure limiting valve
5. Balanced pressure cold draw
off
6. Check valve
7. Expansion valve
8. Expansion valve |
9. Tundish
10. Electrical earthing bond
11. Drain valve
12. Temperature & pressure relief
valve
13. BGC element & thermostat
14. Blank plate (for additional
element, SB only)
15. Element & thermostat assembly |
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|
Useful design formulae - Storage |
Storage
Time in minutes
to heat water
|
= |
Litres x Temp. rise oC
_________________
Kw loading x 14.3
|
Kw loading
required to heat
water
|
= |
Litres x Temp. rise oC
_________________
Time in minutes x 14.3
|
Hot water
required |
= |
Mixed water required
x
Temp.diff. mixed oC
________________
Temp. difference: hot/cold oC |
|
|
Instantaneous Water Heating |
Guidelines for instantaneous water heater sizing |
| |
|
|
Application |
Load per outlet Kw |
Performance* |
| Spray tap |
3.0 |
1.6L/m at 37oC |
| Bib tap |
6.0 |
3.2L/m at 37oC |
| Shower |
8.0 |
4.2L/m at 37oC |
| Hairdresser |
8.0 |
4.2L/m at 37oC |
| Sink |
12.0 |
4.3L/m at 37oC |
| Commercial sink |
24.0 |
8.6L/m at 37oC |
| Bath |
24.0 |
11.4L/m at 37oC |
|
Instantaneous flow chart * |
| |
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| oC |
Loading in Kw |
| |
4 |
6 |
8 |
12 |
18 |
21 |
24 |
45 |
60 |
90 |
| 40 |
1.9 |
2.9 |
3.8 |
5.7 |
8.6 |
10.0 |
11.4 |
21.4 |
28.6 |
42.9 |
| 45 |
1.6 |
2.5 |
3.3 |
4.9 |
7.4 |
8.6 |
9.8 |
18.4 |
24.5 |
36.8 |
| 50 |
1.4 |
2.1 |
2.9 |
4.3 |
6.4 |
7.5 |
8.6 |
16.1 |
21.5 |
32.2 |
| 55 |
1.3 |
1.9 |
2.5 |
3.8 |
5.7 |
6.7 |
7.6 |
14.3 |
19.1 |
28.6 |
| 60 |
1.1 |
1.7 |
2.3 |
3.4 |
5.1 |
6.0 |
6.9 |
12.9 |
17.2 |
25.7 |
| |
Flow rate L/m |
|
Useful design formulae - Instantaneous |
Instantaneous
Temp. rise oC = |
| | |
