MCDonald MULTIflow Manuale utente
Technical Manual
MULTIflow
Thermal Store Cylinders
Tel: (01592) 611123
www.mcdonaldwaterstorage.com
January 2021
MULTI
flow
Thermal Store Tank Technical Manual
Manual must be completed by Installer and left with Home Owner
Issue 3 13/01/21
1
Contents
Preface.................................................................................................................2
Handling & Storage..............................................................................................3
What is a Thermal Store? ....................................................................................3
Design ..................................................................................................................4
Mains Water Supply ............................................................................................5
Immersion Heaters ..............................................................................................5
Water Treatment.................................................................................................6
Pipework..............................................................................................................7
Discharge/Overflow Requirements .....................................................................7
Showers ...............................................................................................................8
MULTIflow OV: Schematic ...................................................................................9
MULTIflow OV: Connection Heights ..................................................................10
MULTIflow SB: Schematic..................................................................................11
MULTIflow SB: Schematic & Connection Heights..............................................12
Technical Data ...................................................................................................13
Installation Schematic (Open Vented)...............................................................14
Installation Schematic (Sealed System).............................................................15
Commissioning ..................................................................................................16
Troubleshooting.................................................................................................18
Warranty............................................................................................................19
Ancillary Descriptions ........................................................................................21
Commissioning Checklist ...................................................................................22
Notes..................................................................................................................25
Issue 3 13/01/21
2
Preface
An early adopter of the principal of domestic thermal stores, McDonald Water Storage
first started manufacturing thermal stores in early 1990s. Manufactured by our trained
coppersmiths and designed based upon the experiences of our technical team. The
McDonald Water Storage MULTIflow provides the perfect solution for mains pressure
hot water.
The MULTIflow Thermal Store Installation & Technical Manual should be read in
conjunction with the installation and servicing manuals issued by the manufacturer(s)
of the heat source(s) used within the thermal storage system.
This information provided is intended to provide support with the installation of the
MULTIflow thermal storage system. Responsibility for selection and specification of our
equipment remains that of our customer and any experts or consultants concerned with
the installation(s). Our full Terms & Conditions of Sale are available on request.
The MULTIflow thermal storage system is required to be fitted by a competent installer,
in accordance with Building Regulations G, Gas Safety Regulations, and the Water
Fitting Regulations (England and Wales),Water Fitting Regulations (Northern Ireland)
or Water Byelaws (Scotland).
(Please note the MULTIflow overcomes Safety implications within Building Regulations G3
relating to pressure and temperature discharge requirements, the installation of the MULTIflow
may be notifiable to the relevant building control.)
Issue 3 13/01/21
3
Handling & Storage
It is important the MULTIflow is handled with care and stored the correct way up in a
dry place at all times prior to, during and after installation.
Carrying handles are provided in the back of the casing to assist with lifting and
positioning. DO NOT LIFT BY THE PIPEWORK as this can loosen off the pre-tested
pipework and may result in leaks. It is good practice to check the joints before filling
with water in case anything has been loosened in transit. Any manual lifting will need
to comply with the requirements of the Manual Handling Operations Regulations issued
by the Health & Safety Executive. For installations on higher levels of properties such
as the 4th floor it is recommended as best practice for the MULTIflow to be moved
vertically within a lift.
What is a Thermal Store?
•Initially the Thermal Store is filled through either the integral, or a remote,
Primary Feed & Expansion Tank.
•The primary store of water is designed to be heated by Immersion Heaters, Gas
/ Oil Boiler or Central Plant Systems.
•Mains pressure water is fed and heated via a secondary heat exchanger, which
draws its heat from the primary store of water.
Issue 3 13/01/21
4
Design
The copper MULTIflow Thermal Store is a primary store that is very well insulated to
ensure minimum Heat Loss and optimally designed to meet the stringent requirements
of ERP.
Cold water at mains pressure passes through a High Efficiency Coil, which is specifically
designed to draw heat from the thermal store at mains pressure. This heated water is
subsequently blended with cold mains water through a Thermostatically Controlled
Mixing Valve, to provide mains pressure water at circa 55°C to the taps and showers.
The Secondary Pipework Loop (DHW Coil & External Pipework) can contain a total of
3 - 5 Litres of water and incorporates an expansion bottle to accommodate the thermal
expansion of the heated mains water. If the volume of the secondary pipework loop
exceeds 15 Litres, then the installer must fit suitable relief valves and appropriately
sized expansion vessels.
The main benefit of the Open Vented Thermal Store configuration is that there is no
onerous discharge restrictions, as required with Unvented Storage Cylinders under G3
regulations.
Where applicable, it also allows the Boilers to input all their power into the store and
reduces boiler cycling.
Being a thermal store that is vented, it is inherently safe and requires no annual
maintenance. Its benefits go one step further as being a primary store there is no
legionella risk, having a blending valve ensures in-built scald protection and then
primary store is not subject to scale build up.
Issue 3 13/01/21
5
Mains Water Supply
The MULTIflow’s performance is largely related to the cold water supply pressure and
flow rate incoming to the property.
•The mains supply to the unit should ideally be in a minimum of 22mm diameter
but will work with 15mm if there is adequate pressure and flow rate.
•The MULTIflow will operate with a minimum incoming mains pressure of 1.0 Bar
and a minimum flow rate of 20 Litres/minute.Careful consideration should be
made to ensure the pressure of hot and cold supplies are balanced.
•An incoming pressure of 2.1 Bar is the most optimal for performance.
•If the incoming pressure exceeds 3 Bar, then a pressure reducing valve must be
fitted after the stopcock of where the incoming cold supply enters the property.
•No Pressure Reducing Valve or Check Valve should be fitted within 2 metres of
the Cold Inlet to the MULTIflow Coil.
•If the flow rate exceeds 15 Litres per minute at any tap, it should be restricted
to maintain the performance of the system as a whole.
Immersion Heaters
•Immersion Heaters are preset to ensure the store temperature reaches 70°C
(maximum 75°C) once the unit is heated.
•The Immersion Heater thermostats are preset with the control setting at 70°C
and the high limit setting at 90°C. The control setting can be lowered or
increased as required for the installation requirements.
•If in any doubt of how to set the Immersion or what temperature we would
advise for specific installations, please contact us on 01592 611123.
•All Immersion Heaters should be wired by a qualified electrician as shown
below, for further information refer to literature provided with the immersion;
Issue 3 13/01/21
6
Water Treatment
In accordance with the Building Regulations L1A: New Dwellings/ L1B: Existing
Dwellings, the requirements set out in the Domestic Building Services Compliance
Guide specify that “where the mains water hardness exceeds 200ppm provision should
be made to treat the feed water to water heaters and the hot water circuit of
combination boilers to reduce the rate of accumulation of lime scale”. In most instances
of this water condition, an inline Water Conditioner/Scale Inhibitor would be fitted to
the incoming mains.
The water quality shall be in accordance with European Council Directive 98/83/EC, or
revised version at the date of installation, and is not fed with water from a private
supply. Particular:
•Chloride content: Max. 200 mg/l
•Sulphate content: Max. 200 mg/l
•Combination chloride/sulphate: Max. 300 mg/l (in total)
The MULTIflow is part of the primary system the Boiler models (where applicable) and
other parts of the primary circuit will require the application of a protective scale and
corrosion inhibitor such as Fernox to ensure adequate protection. This should avoid
having corrosive material in the primary system and remove any build-up of sludge
which can reduce the performance of the High Efficiency Heat Exchanger Coil.
The volumes and concentration of inhibitor required should be calculated in accordance
with the manufacturer’s instructions. Please ensure that the thermal store volume is
also included as well as the radiator and pipework volume.
While we strongly recommend it, inhibitor is optional where the units are utilised with
electricity only. However if there are doubts regarding the quality of water being used
to fill the MULTIflow, an inhibitor should be added to the appliance when filling in line
with the manufacturer’s instructions for these products.
Please note that in all MULTIflow models, the primary water within the thermal store
water is used as primary storage and the domestic hot water is heated instantaneously
by means of the High Efficiency Heat Exchanger Coil. Therefore, treating the primary
water will not have an effect on the domestic hot water supply.
Issue 3 13/01/21
7
Pipework
It is imperative to achieve balanced supply of hot and cold water in a mains pressure
system, and that the piping in a dwelling should be sized in accordance with BS 6700.
However, the following rule of thumb guidelines should be adequate for most of the
smaller property types as long as water pressures are within the recommended range.
•The cold feed from the main incoming stop tap to the MULTIflow should be run
in 22mm pipe. The cold main and hot draw-off should also be run in 22mm as far
as the branch to the bath tap.
•A 15mm copper or equivalent external service may be sufficient for a small 1
bathroom dwelling (depending upon the flow rate available), but the minimum
recommended size for new dwellings is 22mm (25mm MDPE).
•The internal branches to the hand basins and sinks should be in 10mm and to the
baths and showers in 15mm. (1 metre minimum)
•A pressure reducing valve must be fitted after the stopcock of where the
incoming cold supply enters the property and at least 2 metres away from the
inlet to the Secondary Water Coil.
Discharge/Overflow Requirements
The MULTIflow is a Vented Thermal Store and therefore does not require safety
discharge from a Pressure and Temperature Relief Valve as highlighted in Part G of the
Building Regulations.
The MULTIflow Thermal Store can be sited anywhere within the property as no
discharge pipework is required. A manual fill Feed and Expansion tank is provided as
standard and we would recommend wherever possible, to ensure an overflow pipe is
connected to a suitable discharge point.
On the OV model, if an open vented central heating system is to be run, ensure a
minimum 500mm from the highest point of the radiator circuit and the bottom of the
Feed & Expansion Tank. Once the unit is filled through the pipework, close off the
isolation valve and disconnect the flexible hose from the pipework and cap the pipe to
avoid any dead legs.
Issue 3 13/01/21
8
An Automatic Fill version is available as an optional extra at the time of order. The
overflow must be run to a suitable drain point. A tundish is supplied with the automatic
fill kit, if the overflow termination is difficult to see. The tundish must be fitted vertically,
with continuous fall of the overflow pipe.
The overflow should be run in either 22mm copper tube or high temperature overflow
pipe with suitable supports. Ensure that the overflow is capable of coping with a ball-
valve fail situation and restrict flow to the ball-valve accordingly.
Showers
•MULTIflow cylinders are compatible with all showers.
•Most commonly used are of the Thermostatic Mixing type. All mains pressure
systems are subject to dynamic changes particularly when other hot and cold
taps/showers are opened and closed. This will cause changes in the inlet hot
water temperature and pressure at mixed water outlets such as showers.
•Careful consideration should be taken in selecting specification of the shower
valve to ensure the correct mixed water temperature and pressure is
maintained and that it is suitable for the type of people using it.
•Some showers in the TMV2 range have about a 10 degree differential between
the hot inlet temperature and the mixed outlet temperature, allowing
showering temperatures of up to 48 degrees.
•Other valves such as TMV3 only allow maximum temperatures of 41 degrees.
•Commissioning should ensure that the hot draw off from the thermal store is
set taking this into account.
•Please ensure that the shower head is capable of taking mains pressure.
•Please ensure that the shower tray drain is capable of handling the shower
head flow rate. A flow restrictor may be required in the shower outlet hose.
•The hot water supply to a shower-mixing valve should be fed wherever
practical directly from the MULTIflow or be the first draw-off point on the hot
circuit.
•The cold supply to a shower-mixing valve should wherever practical be fed
directly from the incoming mains. To ensure balanced pressure for the shower
mixing valve, a pressure reducing valve must be fitted after the stopcock of
where the incoming cold supply enters the property.
•The shower must incorporate or be fitted with the necessary check valves to
provide back-syphonage protection in accordance with the Water Regulations.
Issue 3 13/01/21
9
MULTI
flow
OV: Schematic
Standard manual fill model shown above.
3kW
3kW
Expansion Pipe
Feed Pipe
Hot Out
c/w Thermostatic
Mixing Valve
Expansion
Bottle
Cold Mains
Secondary Water
High Efficiency
Secondary Coil
Boiler Flow
Boiler Return
Immersion Heater
(On Peak)
Boiler Control Stat
@ 70⁰C
Drain
Immersion Heater
(Off Peak)
Sight Glass
Indice
Altri manuali MCDonald Scaldabagno
