Scandia House, Boundary Road,
Woking, Surrey GU21 5BX
Tel: +44 (0) 1483 771 910
Fax: +44 (0) 1483 227 519
Email: info@sav-systems.com
Web: www.sav-systems.com
HIU FlatStation specification indirect (based on SAV HIU FlatStation 7 Series)
Hot water and heating to each apartment shall be provided by means of wall mounted heat
interface units located in each apartment and fed from the main community heating
distribution system.
Heat interface units shall have the following operating capabilities:
Table 1:
Operating limits and demands
Nominal pressure
Max. heating supply temp.
Min. DCW pressure
Max. primary pressure differential
Hot water temp. settable range
Heating system settable range
Hot water temp. control (max.)
Max. idle function by-pass temp.
Energy rating for pump in sec. side
Max DHW capacity
Max heating capacity
7 Series BS
PN10 bar
120 °C
0.5 bar
4.5 bar
20-60 °C
30-100 °C
± 2.5 °C of set value
=DHW set value
A level
90 kW
40 kW
7 Series DS
PN10 bar
120 °C
1.0 bar
4.5 bar
45-65 °C
30-100 °C
± 2 °C of set value
=DHW set value -8 °C
A level
59 kW
35 kW
OPTIONAL CLAUSES REGARDING APPEARANCE AND THERMAL INSULATION:
Heat interface units shall have white lacquered stainless steel covers suitable for locating in
occupied areas.
OR
Heat interface units shall have white lacquered stainless steel covers suitable for locating in
occupied areas, and thermal insulation of internal components to minimise heat losses.
(Available for the 7 Series DS.)
July 2012
Technical specification subject to change without notice
Page 1 of 3
OR
Heat interface units shall have moulded thermal insulation casings suitable for locating in
unoccupied areas such as cupboards. The thermal insulation casings must have a thermal
conductivity around 0.039*W/m*K. (Available for the 7 Series DS.)
Heat interface units shall incorporate a thermostatically controlled instantaneous hot water
heater, and a branch connection for a central heating circuit with specific features as
described below.
Hot water heaters
The instantaneous hot water heaters inside each heat interface unit shall heat incoming
mains cold water via a plate heat exchanger using heated water from the community
heating system.
Hot water heaters shall have the following features integral to the heat interface units:
 Thermostatic control of hot water temperature enabling a constant, pre-settable hot
water supply temperature (as specified in table 1) at all times, regardless of
temperature or pressure variations in the community heating system and cold water
supply. (Note: there should be no requirement for localised thermostatic mixer
valves at outlets, unless required by special building types.)
 Thermostatically controlled by-passes to ensure a constant, low level flow of water
from the community heating system through the unit, ready to cope with sudden
demands in hot water (see idle function requirement in table 1).
Central heating circuits
Water for central heating systems shall be heated via a plate heat exchanger located inside
each heat interface unit. The plate heat exchanger shall be used to transfer heat from the
community heating system (the primary side) to a separate circuit capable of feeding
radiators or under-floor heating within each apartment (the secondary side).
The following components shall be provided as integral to the heat interface units:
 A strainer in the primary pipework to protect the primary side of the plate heat
exchanger from circulating debris.
 A differential pressure control valve in the primary side pipework to maintain a
constant pressure differential across the plate heat exchanger, regardless of
variations in pump speed or valve closures in other parts of the community heating
system.
July 2012
Technical specification subject to change without notice
Page 2 of 3
 A 2 port on/off control valve on the return of the primary side pipework to prevent
energy loss when no heating is required.
 A wiring box with connection to separate timer, which energises the primary control
valve. The wiring box must also have a wired connection to the secondary side pump
allowing for this to be switched on and off according to heating demand.
 An energy meter in the primary side pipework to monitor the heating energy
consumption to the apartment. The measuring accuracy of the energy meter must
meet the requirements of EN 1434 (MID) class 2.
 A two port thermostatic control valve in the primary side pipework, controlled such
that the secondary side flow temperature is maintained at a fixed pre-settable value
(suitable for either radiators or under-floor heating) as detected by a temperature
sensor located in the secondary side flow pipe.
 A pump in the secondary side pipework incorporating a modulating variable speed
pressure controlled operation mode, for circulation of water to the central heating
system.
 A strainer in the secondary side pipework to protect the secondary side of the plate
heat exchanger.
 An expansion vessel in the secondary side pipework to accommodate expansion of
secondary circuit water.
 A safety valve and drain off cock in the secondary side pipework to provide pressure
relief in the event of a malfunction.
Installation
Heat interface units shall be supplied with ball valves in all pipework connections to and
from the units.
Primary/community heating system connections shall have facility for installation of
pressure test points on flow and return connections for checking of pressure differentials
across the units.
Primary/community heating system connections shall have a fixed full bore by-pass to allow
flushing of the system pipework without having to circulate flushing water through the heat
interface unit.
Depending on the circumstances, pipework connections to heat interface units shall be
either bottom fed, top fed, or mixed.
July 2012
Technical specification subject to change without notice
Page 3 of 3