EN 15332:2007 – Heating boilers – Energy assessment of hot water storage systems
1 Scope
This European Standard specifies a method for the energy assessment of a domestic hot water system comprising an external heating boiler of specified minimum output indirectly heating an unvented (closed) hot water tank of up to 1 500 l. Whilst tanks intended primarily for direct heating are not covered by this European Standard, it does allow the provision of electric heating elements for auxiliary use.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12897, Water supply — Specification for indirectly heated unvented (closed) storage water heaters
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
indirectly heated un-vented (closed) hot water storage tanks
storage vessels used for heating up domestic hot water with an external heat source where the hot water side is not vented to atmosphere, including all devices delivered with it
3.2
hot water side
side of the storage tank which contains domestic hot water
NOTE If a mixing valve is delivered with the storage tank, it is considered as part of the hot water side.
3.3
heating side
side of the storage tank which contains the heating medium
3.4
temperature of the cold water
ϑ ϑ c
temperature at the entrance of the hot water side of the storage tank in °C
3.5
temperature of the warm water
ϑ ϑ w
temperature at the outlet of the hot water side in °C
3.6
usable hot water temperature
ϑ ϑ u
minimum temperature for the hot water to be usable
NOTE Minimum temperature for the hot water defined here as difference between the temperature of the warm water ϑ w = 45 °C minus the temperature of cold water ϑ c = 10 °C ( ϑ u = ϑ w – ϑ c = 35 K).
3.7
heating medium supply temperature
ϑ ϑ h
heating medium temperature at the entrance of the heating side of the water heater
3.8
heating medium return temperature
ϑ ϑ r
heating medium temperature at the outlet of the heating side of the water heater
3.9
storage temperature
ϑ ϑ s
temperature of the storage tank measured at the thermostat position, which is intended for this purpose
3.10
ambient temperature
ϑ ϑ a
temperature in the environment of the hot water storage tank measured according to 5.4.1
3.11
storage excess temperature
∆ ∆ ϑ ϑ x
temperature difference between the storage temperature and the ambient temperature:
a s x
ϑ ϑ ϑ ∆ − =
3.12
tapping volume flow
V w
flow of warm water through the hot water side in l/s
3.13
tapping mass flow
m w
flow of warm water through the hot water side in kg/h
3.14
loading mass flow
m l
flow of heating medium through the heating side in kg/h
3.15
rated storage capacity
C R
capacity of the storage tank assigned by the manufacturer in l
EN 15332:2007 – Heating boilers – Energy assessment of hot water storage systems