Hamworthy Milborne 500 Series User manual

IMPORTANT NOTE
THESE INSTRUCTIONS MUST BE READ
AND UNDERSTOOD BEFORE INSTALLING,
COMMISSIONING, OPERATING OR
SERVICING EQUIPMENT
MILBORNE 500 SERIES
BOILERS
Wall Hung, Pre-Mix, Condensing,
Modular Boilers
Design Installation, Commissioning
and Operating Instructions
NATURAL GAS I
2H
LPG - PROPANE I
3p

Technical Enquiries 01202 662527/662528
To supplement the detailed technical brochures, technical advice on the application and use of products in the
Hamworthy Heating range is available from our technical team in Poole and our accredited agents.
Site Assembly 01202 662555
Hamworthy offer a service of site assembly for many of our products in instances where plant room area is restricted.
Using our trained staff we offer a higher quality of build and assurance of a boiler built and tested by the manufacturer.
Commissioning 01202 662555
Commissioning of equipment by our own engineers, accredited agents or specialist sub – contractors will ensure the
equipment is operating safely and efficiently.
Maintenance Agreements 01202 662555
Regular routine servicing of equipment by Hamworthy service engineers inspects the safety and integrity of the plant,
reducing the risk of failure and improving performance and efficiency. Maintenance agreements enable our customers to
plan and budget more efficiently.
Breakdown service, repair, replacement 01202 662555
Hamworthy provide a rapid response breakdown, repair or replacement service through head office at Poole and accred-
ited agents throughout the UK.
Spare Parts 01202 662525
A comprehensive spare parts service is operated from our factory in Poole, providing replacement parts for both current
and discontinued products. Delivery of parts and components is normally from stock within seven days. However, a next
day delivery service is available for breakdowns and emergencies.
Customer Services

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
MILBORNE 500 SERIES
BOILERS
Wall Hung, Pre-Mix, Condensing,
Modular Boilers
Design Installation, Commissioning
and Operating Instructions
NATURAL GAS I
2H
LPG - PROPANE I
3p
i
NOTE: THESE INSTRUCTIONS SHOULD BE READ AND UNDERSTOOD BEFORE
ATTEMPTING TO INSTALL, COMMISSION OR OPERATE THIS UNIT
PUBLICATION NO. 500001130
ISSUE ‘A’
JUNE 2005

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
ii
CONTENTS
PAGE
1.0 INTRODUCTION ............................................................................................................................... 1
2.0 TECHNICAL FEATURES.................................................................................................................. 2
3.0 CONSTRUCTION DETAILS & DIMENSIONS .................................................................................. 3
4.0 CONTROLS PHILOSOPHY .............................................................................................................. 4
5.0 INSTALLER INSTRUCTIONS .......................................................................................................... 5
6.0 CONDENSATE DISCHARGE ........................................................................................................... 6
7.0 PIPEWORK CONNECTIONS, MANIFOLD KITS, PUMP SELECTION............................................ 7
8.0 FLUE SYSTEM................................................................................................................................11
9.0 VENTILATION ................................................................................................................................. 16
10.0 GAS SUPPLY.................................................................................................................................. 18
11.0 POWER SUPPLY AND WIRING..................................................................................................... 18
12.0 EMERGENCY MODE ...................................................................................................................... 23
13.0 SET-UP FOR MODULAR MILBORNE INSTALLATIONS.............................................................. 24
14.0 PROGRAMMABLE ROOM THERMOSTAT ................................................................................... 27
15.0 COMMISSIONING........................................................................................................................... 29
16.0 MASTER CONTROL PANEL ERROR MESSAGES ...................................................................... 33
17.0 MASTER CONTROL PANEL DESCRIPTION ................................................................................ 37
18.0 USER’S PARAMETER MODIFICATION ........................................................................................ 38
19.0 PROGRAMMING MODE ................................................................................................................. 41
20.0 PROPANE (LPG) ............................................................................................................................ 51
21.0 CONVERTING FROM NATURAL GAS TO LPG............................................................................ 51
22.0 TECHNICAL DATA TABLES.......................................................................................................... 54
23.0 OPTIONS AND KITS....................................................................................................................... 55

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
iii
PICTORIAL AND DIAGRAMATICAL DATA
FIGURES PAGE
Figure 3.1 Basic Dimensions...................................................................................................................... 3
Figure 5.1 Unpacking the Boiler.................................................................................................................. 5
Figure 6.1 Condensate Discharge .............................................................................................................. 6
Figure 6.2 Condensate Discharge .............................................................................................................. 6
Figure 7.1 Pipework Schematic No. 1 ......................................................................................................... 7
Figure 7.2 Pipework Schematic No. 2 ......................................................................................................... 8
Figure 7.3 Single Milborne 502 Pipework Kit ............................................................................................... 9
Figure 7.4 2 x Milborne 502 Pipework Kit .................................................................................................... 9
Figure 7.5 Flow Resistance Graph............................................................................................................ 10
Figure 8.1 Single Milborne 501 Flue Installation......................................................................................... 11
Figure 8.2 Single Milborne 502 Flue Installation......................................................................................... 11
Figure 8.3 Twin Pipe Flue Adaptation Kit................................................................................................... 12
Figure 8.4 Flue Manifold........................................................................................................................... 12
Figure 8.5 Typical Flue Placement Options ............................................................................................... 13
Figure 11.1 External Device Circuit............................................................................................................. 19
Figure 11.2 Pump Wiring Diagram.............................................................................................................. 20
Figure 11.3 Connections to an External Alarm............................................................................................. 20
Figure 11.4 Interlock Circuits ...................................................................................................................... 21
Figure 11.5 Milborne 502 Master - Wiring Diagram...................................................................................... 21
Figure 11.6 Milborne 502 Slave - Wiring Diagram........................................................................................ 22
Figure 12.1 Master Card Emergency Enable............................................................................................... 23
Figure 12.2 Master Card Emergency Enable............................................................................................... 23
Figure 12.3 Master Card Emergency Enable............................................................................................... 23
Figure 13.1 Milborne Multiple Installation..................................................................................................... 24
Figure 13.2 Setting Jumpers, Typical Example............................................................................................ 25
Figure 13.3 Example of Boiler Installation, 7 boiler Modules in same Cascade Sequence.............................. 26
Figure 13.4 Setting Up / Positioning of Room Thermostats .......................................................................... 27
Figure 15.1 Gas Valve Adjustment Points ................................................................................................... 29
Figure 15.2 Gas Inlet Pressure Test Point................................................................................................... 30
Figure 15.3.1 Analysis Point.......................................................................................................................... 30
Figure 15.3.2 LPG Flow Adjustment.............................................................................................................. 30
Figure 15.3.3 Starting the Boiler .................................................................................................................... 30
Figure 15.3.4 Control Panel Modules............................................................................................................ 31
Figure 15.3.5 Master Control Panel Controls, General Overview..................................................................... 31
Figure 15.3.6 LED Positions.......................................................................................................................... 31
Figure 15.3.8 Air Flow Adjustment................................................................................................................. 32
Figure 15.3.11 Gas Flow Adjustment............................................................................................................... 32
Figure 17.1 Control Panel Overview ........................................................................................................... 36
Figure 18.1 Changing Operating Temperature Set-Points............................................................................ 38
Figure 18.2 Entering into Monitor Mode ...................................................................................................... 39
Figure 18.3 User Level Parameters ............................................................................................................ 40
Figure 19.1 Programming Mode / Parameter Lists....................................................................................... 41
Figure 21.2 Gas Valve Air Inlet Positions .................................................................................................... 51
Figure 21.3 Venturi / Gas Valve Positions ................................................................................................... 52
Figure 21.4 Removing Venturi from Gas Valve............................................................................................ 52
Figure 21.5 Venturi Separated.................................................................................................................... 52
Figure 21.6 LPG Orifice Location................................................................................................................ 52
Figure 21.7 LPG Orifice Fitted .................................................................................................................... 52
Figure 21.8 LPG Orifice Options................................................................................................................. 53

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
iv
TABLES
Table 9.1 Air Flow Table for Restricted Space Installations .................................................................. 16
Table 9.2 Air Flow Table for Restricted Space Installations .................................................................. 16
Table 20.1 Technical Table LPG Firing ................................................................................................... 51

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
1
1.0 Introduction
The Milborne 500 series is a range of wall hung
boilers comprising 1 or 2 50kW boiler modules
within a single casing. Having a comprehensive
built-in controls package the boiler is particularly
suited to installations that do not have a dedicated
controls installation.
Where larger installations require more power than
a single boiler can produce then multiple boilers
may be installed in a modular arrangement.
Supplied from the factory as fully assembled units,
the boilers are set up for either natural gas or for
LPG prior to delivery. Where required a modification
may be made on site to change from one gas to
another.
Installation
In order to ensure safety and correct operation, the
installation shall always take place in full compliance
with the applicable Law and with the instructions
provided by the Manufacturer, and will always be
carried out by professionally qualified technical
personnel only. The equipment shall be installed in
a suitable area, and connected to the heating
system in accordance with the applicable Law.
Regulations
The following British Standard Codes of Practice
and Regulations have relevant recommendations
regarding the installation of Milborne boilers.
CR331.3 Low pressure installation pipes.
BS.5449.1 Forced circulation hot water
systems
BS.5446 Installation of gas hot water
supplies for domestic purposes
BS.5440.1 Flues (for gas appliances of
rated input not exceeding 60kW)
BS.5440.2 Air supply (for gas appliances of
rated input not exceeding 60kW)
BS.6798 Boilers of rated input not
exceeding 60kW
BS.6644 Installation of Gas Fired Hot
Water Boilers 60kW – 2MW
BS.6700 Design, installation, testing and
maintenance of services
supplying water for domestic use
BS.6880.1,2 & 3 Code of practice for low
temperature hot water heating
systems of output greater than
45kW
BS.7074.1&2 Application, selection and
installation of expansion vessels
and ancilliary equipment for
sealed water systems. Code of
practice for low and medium
temperature hot water systems
I. Gas E. Publications
IGE/UP/1 Soundness testing and purging
of industrial and commercial gas installations
IGE/UP/1A Soundness testing and direct
purging of small low pressure
industrial and commercial natural
gas installations
IGE/UP/2 Gas installation pipework,
boosters and compressors in
industrial and commercial
premises
IGE/UP/10 Installation of gas appliances in
industrial and commercial
premises Pt1 flued appliances
Health and safety executive
Guidance note PM5 Automatically controlled
steam and hot water boilers
Warranty
Full warranty assistance will be ensured when the
appliance is commissioned by Hamworthy Heating
Ltd commissioning engineers, please see Terms
and Conditions for full details.
The Manufacturer disclaims any and all
responsibility resulting from damage due to
tampering, improper use or mistakes made during
equipment installation, operation and maintenance.
In the event of failure or breakdown, isolate the
equipment and do not try to repair it. Call the
Technical Support Service tel [phone].
Start-Up
The boiler shall be switched on for the first time by
approved Corgi registered engineers only. During
start-up, the engineer shall complete the
commissioning certificate and leave you a copy,
thus starting the warranty period, whose conditions
are specified in the Terms and Conditions available
on request.
Installation and User Manual
This manual shall be read carefully, in order to use
the boiler correctly and safely, and shall always be
kept safely.

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
2
2.0 Technical Features
Milborne 501/502 is a wall-mounted, modular,
condensing, pre-mixed and blown boiler assembly,
consisting of one (Milborne 501) or two (Milborne
502) boilers installed within one casing.
The useful power of each Boiler element reaches
48.50 kW (100%, 50°C-30°C) and is modulating
from 30% to 100%. The efficiency of each generator
reaches 108.6% (nett) in relation to the lower
heating power of natural gas (Hi); thanks to the low
temperatures of flue gas, an integrated flue gas
collector entirely in plastic can be used, having a
50mm diameter and a glass-shaped connection,
which can reach a height of 30 metres.
Milborne boiler assembly series 500 is a great
achievement as regards control, cost-effectiveness,
reliability, and flexibility. Indeed, thanks to the latest
generation electronic management, modularity and
versatility that characterise this product. This boiler
can be rapidly connected to any type of heating
system including systems for the production of
domestic hot water, simultaneously managing three
different systems operating at three different
temperatures.
Milborne 501/502 is fitted with an electronic
management system, making it possible to combine
several boiler assemblies in cascade, to create
boiler installations which can reach an installed
power exceeding 3000 kW.
Individual Boilers can be installed in cascade,
besides applying the traditional lead boiler rotation,
by means of a variable load factor, so that when the
first unit reaches a certain power percentage (e.g.
30%), the following units starts (unison control), all
with the same load factor.
This makes it possible to divide supplied power onto
several heat exchangers with a power: heat
exchanger surface ratio which is particularly useful
to exploit latent condensation heat.
The Milborne boiler offers the following main
advantages:
◊ Total pre-mixing blown air burner.
◊ Condensing heat exchanger with efficiency up
to 109%.
◊ Power from 10 to 100 kW (Single Milborne 502).
◊ Flue gas maximum temperature 80°C
◊ Ø50 mm flue gas pipe up to 30m equivalent
length per boiler module.
◊ Standard condensate discharge system in the
boiler.
◊ Fast connection of water, condensate and gas
using optional pipework header kits, with left or
right hand connections.
◊ Serial connection of E buses between the
various boiler modules and the Master control
panel.
◊ Standard outside weather compensation for
high and low CH circuits.
◊ Control of mixing valve for low temperature CH
circuit.
◊ Modulating and sequential regulation of the
power of individual boilers.
◊ Automatic rotation of lead boiler.
◊ Selection of the burner’s modulation rate within
a cascade control.
◊ Management of domestic hot water and circuits
at different temperatures, with or without
operation priority.
◊ Automatic summer/winter switchover.
◊ Anti-Legionella function (remote control only)
◊ Weekly switch-on time setting (remote control
only)
◊ Priority setting of 3rd pump as either primary or
low temperature CH pump.
(1) See paragraph ‘flue gas exhaust’
(2) Each 90° bend in the piping reduces the
exhaust pipe maximum length by 2 metres.

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
3
Figure 3.1 - Basic Dimensions
3.0 Construction Details
Milborne 501 and Milborne 502 Boiler assemblies
have one or two boilers inside the metal cabinet
respectively.
Each Boiler is connected to the hydraulic system
and the gas supply in parallel (reverse return) to
the others and consists of the following main
components:
◊ Two-way motorised isolation valve.
◊ Heat exchanger.
◊ Pre-mixing burner assembly.
◊ Control and management Slave card.
◊ Safety controls.
◊ 50 mm polypropylene flue gas exhaust
pipe.
Each Milborne 500 Series boiler can be
combined, in series, with other similar boilers, to
create modular boiler installations where the
various boilers are managed by one single
Master control, which can be installed on any of
the boiler assemblies making up the installation.
1. High-efficiency burner and 50 kW heat
exchanger fitted with bi-metal corrugated internal
coil.
- Water side: Copper.
- Flue gas side: stainless steel.
The micro-flame burner is located high, at the
centre of the exchanger, and is a grid type, with
one combined ignition electrode and flame probe.
2. Pre-mixing unit consisting of a modulating gas
valve integrated with a high head fan. The system
ensures a constant mixing ratio in all operating
conditions, and flue gas discharge through a
plastic (PP) exhaust pipe, up to 30 metres
equivalent length.
3. Digital Master control panel. The panel
includes several adjustment functions and is
equipped with a double display, which, depending
on circumstances, shows either the operation
status or the error codes related to the most
common failures.
4. The Master / Slave adjustment system is
located behind the front panel. It consists of a
master control unit that manages on (Milborne
501) or two (Milborne 502) Slave0type control
units. Each slave card controls the operation of
the individual boiler to which it is connected. The
Master card can manage up to 60 Slave cards
and is set for tele-management, temperature
regulation and remote control.
60
0
38
0
1000

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
4
4.0 Controls Philosophy
The Milborne 500 series boiler is supplied with a
sophisticated integrated control system. This system
works with the Master and Slave principle of control
allowing several boilers to be installed all operating
from one control system.
The Master boiler is available as either the Milborne
501 or the Milborne 502. Each Master boiler is
equipped with a digital control panel as the user
interface and heating controller.
Additional Slave boilers are available as Milborne
502 models allowing combinations using one Master
boiler to be assembled as modular installations.
Boiler sequencing is commanded from the Master
boiler with lead boiler rotation based on hours run.
Each Master boiler is supplied with a temperature
sensor for fitting in the common flow pipework. This
must be positioned after the last boiler connection in
a cascade arrangement on the flow pipework
closest to the heating circuits.
Summer shutdown is based on outside air
temperature measured from the outside air
temperature sensor supplied with each Master
boiler. An adjustable parameter allows setting for
the outside temperature at which the heating circuits
are disabled.
Frost protection is also facilitated from the outside
air temperature sensor. Stage 1 will start the primary
pump, or the high temperature heating circuit pump
where a primary pump is not used. Stage 2 will
enable the boilers based on water temperature
within the heating circuit at a temperature configured
in the parameter settings.
Weather compensation is available for the heating
circuits based on outside air temperature and a
common curve. Each heating circuit can be offset
from this curve by setting the maximum and
minimum water temperatures in the parameters.
From the Master boiler it is possible to control 2
heating circuits and a DHW circuit. The heating
circuits are designated as high temperature heating
circuit and low temperature heating circuit. The latter
incorporates control outputs for both the pump and a
mixing valve whilst the high temperature circuit and
DHW circuit have only outputs for pump control.
All 3 circuits can be set in the parameters to operate
at different temperatures. The low temperature
heating and DHW circuits have additional optional
sensors for control of water temperature.
DHW can be set in the parameters to operate with
traditional calorifiers or plate heat exchangers using
voltage free switching thermostats.
Where the heating circuits are controlled from the
Master boiler control panel and not all three
secondary heating circuits are installed, the unused
circuits can be disabled in the parameter settings.
Pump designation
A maximum of 3 pumps can be controlled from the
Master boiler. Should a primary pump be required
for a primary circuit, then pump 3, normally used for
the low temperature heating circuit, must be re-
designated in the parameter settings as a primary
pump. The secondary circuit capability of the boiler
is then restricted to DHW and high temperature
heating.
However the high temperature heating circuit can be
set to operate at condensing low temperatures and
use weather compensated flow temperature.
Pump control.
When using weather compensated heating circuits
with DHW the pumps are controlled in the following
manner.
When there is a DHW demand requiring higher
primary temperatures the pump for the high
temperature heating circuit is switched off. For the
low temperature heating circuit the pump remains
running whilst the mixing valve is modulated to
prevent higher temperature water entering the
circuit.
At the end of the DHW demand the DHW pump is
switched off and the high temperature heating circuit
pump switched on again. The low temperature
heating circuit mixing valve is re-modulated to suit
the new primary water temperature. Primary water
temperature is set to the higher of the two heating
circuit requirements.
When only one circuit requires heat the primary
water temperature is set to the requirement of that
circuit.
Pump over-run
A separate adjustable parameter is provided for all
three pumps to facilitate pump over-run. This will
remove residual heat from the boiler when the last
circuit is signalled off by the relevant time clock or
thermostat.
These parameters are set as part of the
commissioning procedure and can be adjusted
between 0 and 255 minutes.
Temperature control
Whilst the maximum and minimum settings for the
heating circuits are set by the parameters at

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
5
commissioning, the user can alter the operating set-
points within these limits via the Master control
panel.
Parameter settings are fixed during commissioning
and cannot be altered by the user.
Time clock control
Time clock control can be provided by time clocks in
series with volt free switching room thermostats, or,
programmable room thermostats utilising volt free
switching contacts to the Master boiler. A separate
time signal is required for each of the heating
circuits. Domestic hot water can be time controlled
using a time clock in series with a volt free switching
cylinder thermostat.
Alternatively the Master boiler can be enabled from
a BMS using a 0-10 V analog input. In these
circumstances it is anticipated that the BMS will
control all secondary circuit functions.
5.0 Installation Instructions
Packing and Product Identification
Milborne series 500 heat generators are supplied on
pallets, packed and protected with strapped
cardboard.
It is important immediately to check for product
integrity and correspondence with the order.
Product features are specified on the outer part of
the packing: model, power, version, and fuel type.
Should the product not match with the order,
immediately contact customer services at
Hamworthy Heating Ltd.
Location
Milborne series 500 Boiler assemblies shall be
installed in accordance with the most recent
applicable standards and technical regulations on
boiler installations and condensing boilers, as with
any other boiler installation.
Wall-mounting
The boiler must be installed on a solid masonry wall
by means of hooks supplied with the boiler, inside
the packing. The hooks position ensuring correct
boiler installation can be determined using the
cardboard template to be found in the packing.
◊ Place the template supplied with the boiler on the
wall, at a height of approximately 140 cm from the
ground, using a spirit level to ensure that the
mounting holes are perfectly horizontal.
◊ Secure the template on the wall temporarily and
mark the boiler’s mounting holes on the wall
◊ Drill the holes and install the screw anchors
supplied with the boiler.
Health and safety. Care must be taken when lifting
the boiler to its securing hooks. The weights are
given in the technical table at the rear of this
manual.
Warning: Milborne Series 500 boiler
assemblies must not be installed
outdoors.
Note.
When installing multiple boilers the Master boiler
must be placed closest to the heating system to
allow correct location for the common flow
temperature sensor.
Figure 5.1 - Unpacking the boiler.

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
6
6.0 Condensate Connection
The condensate water produced by boiler assembly Milborne 501/2 during its normal operation shall be
discharged at atmospheric pressure, i.e. by dripping into a tundish or siphon-shaped container connected as
described in the following procedure:
a) Install a tundish or drip pan under the
condensate discharge system (see position
on installation template).
b) Connect the tundish to the sewage system by
means of a ‘U’ bend.
c) Install a condensate acid neutraliser if
required by the applicable laws.
The tundish (or drip pan) shall be created and
installed in accordance with the applicable technical
standards.
Plastic polypropylene pipes should be used to
create the condensate discharge system as the
acidity in the condensate will rapidly corrode metal
pipes. Never use copper pipes.
Flue system condensate discharge piping
Should it be necessary to extend the vertical or the
horizontal section of the discharge piping to over 4
metres, create a ‘U’ bend at the foot of the pipe. The
siphon’s useful length must be at least 300 mm. The
‘U’ bend discharge shall then be connected to the
drainage / sewage system.
Using the condensate discharge kit, HHL Part No.
573407110, detailed in the flue system section, to
make an easy connection to the flue system for
condensate removal.
Condensate maximum production rate (50°C - 30°
C) 100% output rate.
Milborne 501……….7.2 Kg / h (l/h)
Milborne 502……….14.4 Kg / h (l/h)
Min.
Distance
Slope away from
system 3%
Condensate Trap
Condensate
discharge
pipe
Figure 6.1—Condensate Discharge
Fig 6.2

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
7
7.0 Pipework Connection
System Cleaning
This preventive measure is absolutely required
whenever a heat generator needs to be replaced in
existing systems, but it is in any case recommended
also on new systems, in order to remove any waste,
dirt, working residues, etc.
To clean the system, if the old generator is still
present in the system, it is advisable to:
◊ Add a descaling solution, such as FERNOX
Superfloc at 2% concentration to the system
water volume.
◊ Have the system operate with the circulating
pump for approximately 7 days.
◊ Discharge the system’s dirty water and wash
once or several times using clean water. If the
system is very dirty, repeat the last procedure
until clean.
Figure 7.1 - Pipework Schematic No. 1
Pump the water + additive through the system for
approximately 7 days and perform a final wash as
described in the previous paragraph.
At the end of cleaning operations, before installing
the boiler, it is advisable to add corrosion inhibitor
FERNOX MB-1 AT 4% concentration to the system
water volume
Example of a Milborne installation using a primary circuit with domestic hot water and single
heating circuit.
*See note below Pipework Schematic No. 2 regarding pump control

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
8
Figure 7.2 - Pipework Schematic No. 1
Example of a Milborne installation using domestic hot water with high temperature and low
temperature heating circuits.
*See note below regarding pump control
*The Milborne boiler has the facility to start and control 3 pumps.
It is therefore important when designing the heating system to allow pump number 3 to be assigned as the boiler
primary pump where required (see pipework schematic 1). In all other installations pump 3 will be assigned as the
low temperature heating circuit pump (see pipework schematic 2). Therefore where a primary system pump is
required the control system will not support a low temperature mixing circuit.

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
9
Hydraulic Connections
Figure 7.3 & 7.4 show the hydraulic connections and their size and type.
To make hydraulic connections easier, two kits are available: one for the installation of one single Milborne 502,
figure 7.3, the other for the installation of two Milbornes series 500 as a set, figure 7.4.
Kit for a Single Milborne 502 (up to 100kW)
Hamworthy kit ref. PKS502, HHL Part No
573407124, Fig 7.3.
Comprising of;
1 x gas header, diameter 50 mm.
1 x flow header, diameter 50 mm.
1 x return header, diameter 50 mm.
Each header is fitted with 2 x 25 mm branch pipe
connections for flow and return and 2 x 19 mm for
gas connections to each boiler is made using
isolating valves, and for the flow connections a 3
port isolation vent valve.
Optional wall support brackets as shown.
Kit for two Milborne 502 boilers installed in
series (up to 600 kW)
Hamworthy kit ref PKD502, HHL Part No.
573407125, Fig 7.4
1 x gas header, diameter 3” PN6
1 x flow header, diameter 3” PN6
1 x return header, diameter 3” PN6
Each header is fitted with a 4 x 25 mm branch pipe
connections for flow and return and 4 x 19 mm gas
connections to each boiler unit. Final connection to
the boiler is made using isolating valves, and for
the flow connections a 3 port isolation vent valve.
Standard wall support brackets as shown.
Figure 7.3 - Single Milborne 502
Figure 7.4 - 2 x Milborne 502
Note: When Installing multiple boilers the Master Boiler must be placed closest to the heating system to
allow correct location for the common flow temperature sensor.

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
10
Safety valve
Each 50kW boiler module is supplied with a fitted
safety valve rated at 6 barg. This ¾” valve is piped
to the bottom of the boiler module where it must be
piped to discharge via a tundish (not supplied). The
discharge should be in an obvious position to alert
the responsible person of a problem.
System Pump Size
The pump is not an integral part of the boiler.
Consequently, its size should be chosen considering
the features of the Boiler assembly and of the
system to be fed.
To help choose the correct pump, figure 7.5 shows
the curve of flow resistance values inside the boiler.
Pump Type
Pumps should be of the electronic constant
pressure type. This will ensure that as boiler
modules are turned off and the individual motorised
isolating valves close, flow rates for the remaining
modules are maintained.
Alternatively a fixed speed pump with flat curve
characteristics may be used.
Maximum Operating Pressure
The boiler’s maximum operating pressure is 6 bar,
its minimum operating pressure is 0.5 bar.
Boiler Filling and Draining
The boiler should be filled using the system quick fill
connection. This connection must be removed after
filling.
The boiler should be drained using the relevant
drain valves fitted to the boiler or system.
Flow rate requirements
As a condensing boiler the Milborne is designed for
operation at 20°C differential temperatures. Should
the flow rate drop the boiler will recognise the
change in differential temperature and modulate the
burner to maintain 20°C differential. It is therefore
important to size the pumps based on a flow rate of
0.6 l/sec (2160 l/hr) per 50kW boiler module plus an
allowance for system resistance.
MILBORNE 501
Figure 7.5 - Flow Resistance Graph

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
11
8.0 Flue Gas System
Available for the following flue types
B23 Conventional open flue system drawing combustion air from the room the boiler is installed within.
C63 Room sealed, twin duct, using separately approved flue components for the air supply and flue discharge.
Note: Balanced flues using concentric ducts are not available or approved for this boiler.
Each heat generator (module) inside boiler
assemblies Milborne 501/502 has been validated
equipped with a self-extinguishing polypropylene
flue gas exhaust system (1) with glass-shaped
connections.
As for the air supply system, since boiler assemblies
Milborne 501/502 have been validated as type B or
type C assemblies, air can be taken directly from the
boiler room through specific vacuum pipes (2).
Flue systems must be designed and installed in accordance with the requirements of the relevant standard:
BS5440 for single Milborne 501 installations
BS6644 for single Milborne 502 and multiple boiler installations
Flue Maximum Length.
Each 50 mm flue pipe maximum equivalent length is
30 metres with a maximum 4 metre flow resistance
for each 90° bend and 3 metres for a 45° bend.
Open Flue Installations type B23
Figure 8.1 shows the configuration of a single
Milborne 501 boiler installation using the B23 open
flue arrangement. In this application combustion air
is taken directly from the boiler house.
Figure 8.2 shows the configuration of a single
Milborne 502 boiler installation using the B23 open
flue arrangement. In this application combustion air
is taken directly from the boiler house.
For B23 type open flue arrangements with air intake
from boiler house the maximum equivalent flue
length of 30 metres includes only the flue pipe.
Note: Consideration must be made for the
prevention of condensate from freezing within
the condensate trap at the base of the flue.
Locating the condensate discharge kit to the
horizontal flue section within the building may
provide a suitable solution.
Figure 8.1 - Single Milborne 501 Flue Installation. Related Standard BS5440 Part 1
Milborne 501
Milborne 502
Figure 8.2 - Single Milborne 502 Flue Installation. Related standard BS6644

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
12
Room Sealed Flue Installations Type C63
Figure 8.3 shows the twin pipe flue adaptation kit fitted to a Milborne 502 boiler. This allows the air supply and the
flue to be piped using separate ducts for room sealed applications.
It is most important that horizontal flue terminals are
positioned at least to the minimum requirements, as
shown in Figure 8.5, from other features of the
building , i.e. opening windows etc.
Air supply inlets must be positioned at least 300 mm
from flue terminals to prevent flue gas recirculation.
We recommend that flue terminals are discharged
higher than air inlets.
For C53 twin type pipe installations the maximum
equivalent length of 30 metres includes both the
requirements for the air inlet pipe and flue pipe.
Figure 8.3
To comply with the requirements of the Clean Air Act 1956 a maximum of three (3) 50 kW modules may be
terminated with horizontal flue discharges.
Connection to a Flue Gas Header
The design of the flue system for the installation of several Milborne 500 Series boilers will be easier if a 125 mm
diameter, polypropylene flue gas header with male / female connections is used.
The header is designed to collect the flue gas
from the two 50 mm flue pipes of a Milborne
502, each of which contains a flue gas non-
return valve.
When using the flue gas header for up to
three (3) boiler assemblies connected in
series, the minimum distance required
between the assemblies (150 mm) must be
complied with; see figure 8.4.
In this way, the male end of one of the two
headers will connect more readily to the
female connection of the adjacent header.
Note: When using the 125 mm diameter flue
header the maximum number of 50kW
modules acceptable in a single flue system is
six (6), or 3 x 502 models.
Maximum equivalt flue length when using the
125 mm diameter flue header with 6 x 50kW
modules remains at 30 metres, with a 4
metres reduction for each 90° bend in the flue
system and 3 metres for each 45° elbow.
Maximum pressure available at flue
connection to an individual 50 kW module is
0.7 kPa (7 mbar)
Figure 8.4
Note: Air supply ducts must not be connected together when using room sealed applications. Only
individual air ducts for each module are acceptable.

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
Flue Terminal Locations
The diagram below details the minimum spacing requirements for flue terminals from other building features when
using horizontal flue terminals with C63 twin pipe flue systems.
It is recommended that air supply inlet terminals are positioned no closer than 300mm to any flue terminal when
using C63 twin pipe flue systems. Air supply inlets should preferably be positioned lower than flue terminals.
13
Figure 8.5
Dim Terminal Position Min Dis
(mm)
A Directly below an opening, air brick, opening window etc 300
B Above an opening, air brick, opening window etc 300
C Horizontally to an opening, air brick, opening window etc 300
D Below gutters, soil pipes or drain pipes 75
E Below eaves 200
F Below balconies or car port roof 200
G From a vertical drain pipe or soil pipe 150
H From an internal or external corner 300
I Above ground roof or balcony level 300
J From a surface facing the terminal 600
K From a terminal facing the terminal 1200
L From an opening in the car port (e.g. door, window) into the dwelling 1200
M Vertically from a terminal on the same wall 1500
N Horizontally from a terminal on the same wall 300
O From the wall on which the terminal is mounted N/A
P From a vertical structure on the roof N/A
Q Above intersection with roof N/A
Note: Flue Installation should comply with BS5440 Part 1

HAMWORTHY HEATING LTD MILBORNE 500 SERIES 500001130/A
14
Components for Individual Flues per 50kW Boiler Module
50 mm diameter flue components for use with Milborne 501 and 502 boilers.
For use on applcations consisting of B23 type flue configurations, where combustion air is taken from within the
boiler house, and C53 room sealed twin duct systems where combustion air is taken directly from outside and
ducted to the boiler.
Maximum equivalent length for this flue system is 30 metres from boiler to terminal for B23 applications, and from
air inlet terminal to flue terminal for C63 applications.
Equivalent lengths for 90° bends is 4 metres with 3 metres equivalent length for a 45° bend.
Pictorial View Description HHL Part No.
Polypropylene 45° bend ø50 mm
Polypropylene 90° bend ø50 mm
573407109
573407047
Polypropylene pipe ø50 mm x 250mm
Polypropylene pipe ø50 mm x 500mm
Polypropylene pipe ø50 mm x 1000mm
Polypropylene pipe ø50 mm x 1500mm
573407111
573407112
573407113
573407114
Cravat for flat room ø50 mm 573407115
Cravat for pitched roof ø50 mm 573407116
Stainless steel horizontal wall terminals ø50 mm 573407117
Twin duct horizontal flue discharge / air intake kit.
Consisting of:
2 x 90° bends
2 x ø50 mm x 500mm pipe
2 x ø50 mm x 250mm pipe
2 x Stainless steel wall terminals
573407119
Twin duct vertical flue discharge with horizontal air
intake kit for flat roofs. Consisting of:
1 x 90° bend
2 x ø50 mm x 500mm pipe
1 x ø50 mm x 250mm pipe
1 x Stainless steel wall terminals
1 x cravat for flat roof
573407121
Twin duct vertical flue discharge with horizontal air
intake kit for pitched roof. Consisting of:
1 x 90° bend
2 x ø50 mm x 500mm pipe
1 x ø50 mm x 250mm pipe
1 x Stainless steel wall terminals
1 x cravat for pitched roof
573407123
Polypropylene condensate discharge kit. To
remove condensate from vertical and horizontal
flue sections.
573407110
Polypropylene 50mm vertical flue terminal. 573407131