Regulations
- MIN hot-water storage capacities by BS 6700
- Part L1 of Building Regs - Copper Grade 3 is MIN option for Heat Exchanger and Insulation Level
Minimum Requirements
- 35-45L per occupant (depend on recovery rate of the heat source)
- 100L for systems heated by solid-fuel boilers
- 200L for systems heated by off-peak electricity
- The most common size - 900mm x 450mm, storing 110L
Heat Recovery
- Power = SHC x KG x Δ / Time (sec), where:
- SHC - specific heat capacity of water (4.186kJ)
- KG - the mass of water to be heated
- Δ - temperature rise
Capacity of HWSC
- M=VT/(14.3p) where
- V - volume of water heated in litres
- T - temperature rise in °C
- p - rate of heat input
Heat input for domestic properties
| Heat input to hot water (kW) |
Dwelling with 1 bath |
Dwelling with 2 baths |
| With stratification (l) |
With mixing (l) |
With stratification (l) |
With mixing (l) |
| 3 |
109 |
122 |
166 |
260 |
| 6 |
88 |
88 |
140 |
200 |
| 10 |
70 |
70 |
130 |
130 |
| 15 |
70 |
70 |
120 |
130 |
Stratification
- when hot water in the storage vessel, floats on a layer of cold-feed water
- hot water doesn't mix with cold water inside the cylinder
HWSC Labeling
- Type of vessel
- Nominal capacity (in litres)
- Standing heat loss (in kWh/day)
- Heat exchanger performance (in kW)
- Reference to product compliance with relevant standard
