Alpha Alpha Plus DH Units Guide

Instructions for Installation
Alpha Plus DH Units for Domestic Hot Water
and Low Pressure Central Heating
Alpha Therm Ltd
Nepicar House
London Rd
Wrotham Heath
Kent
TN15 7RS
Leave these instructions with the User

1/ INTRODUCTION
The Alpha Plus district heating units are hydraulic units designed for various
heating applications within individual domestic dwellings served by a district heating
scheme. The units are:-
(i) Domestic Hot Water Unit – Model DHW (Part No 6.3000100)
This unit provides instantaneous hot water indirectly from a district heating
circuit via a plate heat exchanger. The main components are pre-assembled
mounted on a back panel. Isolation valves and strainer are supplied with wall
fixings and thermostat sensor.
(ii) Low Pressure Central Heating Unit – Model LPCH (Part No 6.3000300)
This unit is to be used in conjunction with the unit DHW and provides central
heating to the dwelling indirectly from the district heating circuit via a plate
heat exchanger. It incorporates all the necessary components i.e. pump,
expansion vessel, safety valve, pressure gauge, filling loop, pressure switch
etc required to provide a sealed central heating system with a maximum
working pressure of 2.5 bar (Refer diagrams)
Note: Differential pressure control valves and an automatic by-pass valve for
fitting to the district heating circuit are not provided in the above units and
need to be supplied by the installer.
An optional outer cover (Part no 6.3000400) enclosing the main components of the DHW
or LPCH unit is available, if required.
The above district heating units comply with the following requirements:
Electrical requirements of BS EN60335 – 1
EMC requirements of BS EN55014 – 2, BS EN50081 – 1, BS EN61000 - 3 - 2 / 3
UK Water Regulations / Byelaws (Scotland)
Northern Ireland Water Regulations
IMPORTANT
The installation should be in accordance with the following British Standards and requirements:
All current Dept of Environment Building Regulations , i.e. Approved Document L1
Building Standards (Scotland), Regulations issued by the Scottish Development Department
UK Water Regulations/Byelaws (Scotland)
Health & Safety Document No. 635 (The Electricity At Work Regulations 1989)
BS 5449: 1990 Forced circulation hot water system
BS 5546: 2000 Installation of hot water supplied for domestic purposes
BS 6700: 1997 Design, installation, testing and maintenance of services supplying water
BS 7983: 1992 Code of Practice for treatment of water in heating systems
BS 7671: 2001 Requirements for electrical installations, IEE Wiring Regulations
Note: Manufacturer’s instructions must NOT be taken in any way as over-riding statutory
obligations
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2/ TECHNICAL DATA
2.1 District Heating Circuit
Max Working Pressure 8 bar
Min Working Pressure 1 bar
Max Flow Temperature 95°C
Max Differential Pressure 4 bar
Flow connection 22mm
Return connection 22mm
2.2 Secondary Circuit (Domestic Hot Water)
Max Working Pressure 8 bar
Min Working Pressure 0.2 bar
Heat Output to water (approx) 20 to 28kW
DH circuit flow rate reqd for max output 15 to 20 l/min
Max Flow Rate at 35°C rise (approx) 12 l/min
Min required Flow Rate 2.5 l/min
Adjustable Outlet temperature up to 60°C
Max Outlet Temperature (approx) 62°C
Mains inlet connection 15mm
DHW outlet connection 15mm
2.3 Low Pressure Central Heating (Sealed System)
Max. working system pressure 2.5 bar
Min System Pressure 0.5 bar
Max System temperature 85°C
Safety Valve setting 3 bar
Expansion Vessel Size (pre-charge press)8 L @ 0.8 bar
Flow Connection 22mm
Return Connection 22mm
Relief valve discharge connection 15mm
Recommended System Pressure (Cold) 1.0 bar
2.3 Components
DHW Heat Exchanger Stainless Steel 23 plate
CH Heat Exchanger Stainless Steel 14 plate
Hot Water Thermostatic Valve Brass body with removable t/sensor
CH/DHW on/off 2-way Valve Brass body with removable actuator
DHW Flow Switch with Strainer Nylon with ½” Brass connection
Strainer for DH and CH Brass 22mm comp with S/S filter
DH/CH Isolation Valves Brass 22mm comp.
Cold Water Inlet Valve Brass 15mm comp
Pump with AAV & Separator Grundfoss 15/60
LP Pressure Switch Set 0.5 bar switching
Expansion Vessel 8 litre charge to 1 bar
Pressure Relief Valve/Gauge Set 3 bar
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2.4 Electrical
Supply – 230/240V – 50 Hz
External fuse - 3 A
Power Consumption – 116W
Important – Ensure terminal block 2 (supplied with LPCH unit) is fitted within the DHW
control box, if not already fitted
2.5 Installation
Dimensions of each assembled Unit Height 500mm
(Including Cover) Width 300mm
Depth 220mm
Min clearances required Top 5mm
Bottom 200mm
Sides 5mm
Front 450mm
Assembled weight of Units DHW 7.4kg
LPCH 8kg
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2.6 Schematic Diagram
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3/ OPERATION
Domestic hot water is available continuously and always takes priority over central
heating. If a demand for hot water is required during a central heating period the
controls will automatically switch to the hot water mode until the demand is
satisfied. This interruption in the central heating is only when the demand for hot
water is present and should not be noticed by the User.
3.1 Domestic Hot Water mode
When there is a demand for hot water the flow switch operates and the DHW valve
is opened via a relay. District heating water is circulated to the DHW heat
exchanger thus heating the incoming mains water. The hot water is maintained at
the set temperature by the hot water thermostatic valve regulating the district
heating water flow to the heat exchanger. When the flow switch senses that hot
water is no longer required the DHW valve closes.
3.2 Low Pressure Central Heating
If there is a call for heating from an external control the CH valve opens and district
heating water is circulated to the CH heat exchanger. The pump will start and
circulate the central heating water to the dwelling’s radiators via the heat
exchanger. When there is no demand for heating the CH valve will close and the
pump will stop. If there is a demand for hot water the CH valve will close and not be
allowed to open until the hot water demand has been satisfied.
Note: If the pressure in the central heating system falls below 0.5 bar the pressure
switch will operate and stop the pump from running until the system has been re-
pressurised above 0.5 bar
4/ INSTALLATION
4.1 Unpacking
(1) The contents of each box is as follows:
DHW Box - Assembled unit panel mounted with heat exchanger,
flow switch, DHW valve, HW thermostatic valve, control
box and pipework
Thermostat and sensor
Thermostat sensor fixing kit, screws and wall plugs
Two 22mm isolation valves, strainer, 15mm Isolation valve
LPCH Box - Assembled unit panel mounted with heat exchanger, pump
with AAV and separator, CH valve, pressure switch and
pipework
Four 22mm isolation valves, strainer, screws, wall plugs
Terminal block 2
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(2) Unpack and remove loose items
4.2 Unit Location
(1) The unit is not suitable for external installation. It must be installed vertically on
a flat vertical wall which is capable of supporting its weight.
(2) Decide upon the position of the unit taking into consideration the clearances
required (Refer Sect 2.5)
(3) Refer to diagram below for the layout and location of the two units:
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4.3 Fit the DHW Unit
(1) Drill four fixing holes (5mm dia) through the back panel of the unit to accept
the No. 8 screws supplied.
(2) Hold the unit on the wall in the required position ensuring it is level and mark the
position of the fixing holes. Then drill the fixing holes (6mm dia) in the wall to
accept the No.8 wall plugs.
(3) Using the screws supplied secure the unit to the wall.
4.4 Fit the Thermostat and Sensor (Refer Diagram 4.2.3)
(1) Unscrew the plastic cap on the HW thermostatic valve body and remove.
(2) If applicable, remove the pocket from the capillary tube sensor and discard.
Then locate the thermostat onto the valve body by tightening the loose nut by
hand onto the thread of the body.
(3) With care unwind the capillary tube and position the sensor onto the location
provided on the outlet pipe from the heat exchanger.
(4) Secure the sensor in position using the tape supplied. Then locate the
insulation supplied around the sensor and secure with the two straps provided.
4.5 Connect the Pipework (Refer Diagram 4.2.3)
(1) Thoroughly flush out ALL the system pipework.
Note: An automatic system by-pass must always be fitted.
(2) Connect the 15mm isolating valve to the cold inlet pipe of the unit and then
connect the domestic hot water pipework.
(3) Using a ‘T’ connection, Connect the DH flow and return of the DHW unit and fit
the LPCH unit in the position shown in the diagram 4.2.3 and as detailed in
section 4.2 and 4.3.
Note: Ensure the LPCH unit is located within 300mm of the DHW unit. This will
allow the cables to be directly connected into the unit’s control box.
(4) Fit the 22mm strainers supplied to the DH flow pipe and to the CH return pipe.
Ensure the strainers are always fitted after the valves so that isolation allows
cleaning of the filter (Refer diagram 2.6)
4.6 Fit the Sealed System Kit
(1) Assemble the components of the sealed system kit as shown in the instruction
supplied in it’s box. Note: Check the expansion vessel has been charged to 1
bar before connection to the system.
(2) Using the 22mm ‘T’ connector and 22mm to 15mm reducer supplied connect
the kit to the CH system, preferably on the return to the pump.
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Note: The pressure relief valve discharge pipe must be routed to a drain in such a
manner that it may be seen, but cannot cause injury to persons or property.
4.7 Fit Terminal Block 2, If Not Already Fitted (Supplied with the LPCH unit)
(1) Gain access to the DHW terminal block by releasing the 4 screws securing the
control box cover.
(2) Connect the terminal block 2 to terminal block 1 as follows (Refer diagram 2.4):
Brown wire to terminal 6, Blue wire to terminal 3, Green/Yellow wire to earth.
(3) Locate terminal block 2 into the control box as shown in diagram 4.10.6
4.8 Connect the CH Valve Electrical Cable (Refer Sect 2.4)
(1) Gain access to the DHW terminal block by releasing the 4 screws securing
the control box cover.
(2) Pass the CH valve’s electrical cable through a cable clamp and connect the
wires to terminal block’s 1 and 2 as follows (Refer diagram 2.4);
Brown to terminal 7, Black to terminal 9, Blue to terminal 3, Grey to terminal 13,
Orange to terminal 12, White wire not used ensure to terminate it safely.
(3) Tighten the cable clamp by hand until the cable is secured.
4.9 Connect the CH Pump electrical cable
(1) Pass the CH pump’s electrical cable through a cable clamp and connect the
wires to the terminal block 2 as follows (refer diagram 2.4);
Brown to pump ‘L’ (no11), Blue to pump ‘N’ (no10), Green/Yellow to pump earth
(2) Tighten the cable by hand until the cable is secured.
4.10 Connect the LP Pressure Switch
(1) Pass the LP pressure switch cable through a cable clamp and connect the wires
to terminal block 2 as follows (refer diagram 2.4):
Brown wire to terminal 13, Blue wire to terminal 11
(2) Tighten the cable by hand until the cable is secured.
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4.10 Connect the Electrical Supply (Refer Sect 2.4)
The Unit requires a 230/240V ~ 50Hz mains supply, fused at 3A
The Unit must be earthed.
There must be only one common isolator, providing complete electrical isolation, for
the Unit and any external controls.
Using PVC insulated cable not less than 0.75mm²(24 x 0.2mm) to BS6500 Table 16,
the Unit should be connected to a fused three pin plug and unswitched shuttered
socket outlet (both complying with BS1363), or a fused double pole switch with a
contact separation of at least 3mm in both poles.
Wiring external to the Unit must be in accordance with the current IEE Wiring
Regulations (BS7671).
NOTE:If external controls are fitted, they MUST be suitable for 230/240V
switching and MUST be single pole, 2 way / Changeover switching
The procedure is as follows:
(1) Gain access to the terminal block as in 4.7.1.
(2) Pass the mains supply cable through the cable clamp and connect as follows:-
Brown to L, Blue to N and Green/Yellow to earth. Ensure correct polarity.
Note: Ensure that the length of the earth wire is such that if the supply cable
is pulled out of its clamp the live and neutral wires become taut before
the earth wire.
(3) If an external control i.e. room thermostat or external clock is to be fitted,
remove the link between terminals 8 and 9. Pass the cable through the cable
clamp and connect to terminals 8 & 9 using terminal 9 as switched live.
(4) Ensure there is sufficient free cable to allow the control box cover to be
removed giving easy access to the main terminal block, then tighten the cable
clamps by hand.
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