Potterton Promax 15 HE User guide

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Installation and
Servicing Instructions
Please leave these instructions with the user
Promax 15 HE & 24 HE
Wall Mounted Powered Flue Condensing Boiler
Gas Fired Central Heating Unit

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2
Natural Gas
Potterton Promax 15 HE
G.C.No41 590 58
Potterton Promax 24 HE
G.C.No41 590 62
The boiler meets the requirements of Statutory
Instrument “ The Boiler (Efficiency) Regulations
1993 No3083” and is deemed to meet the
requirements of Directive 92/42/EEC on the energy
efficiency requirements for new hot water boilers
fired with liquid or gaseous fuels:-
Type test for purpose of Regulation 5 certified by:
Notified Body 0051.
Product/Production certified by:
Notified Body 0086.
For GB/IE only.
Guarantee
Your Potterton Promax 15 HE or 24 HE
are designed and produced to meet all
the relevant Standards.
Potterton provide a 12 month
guarantee on the boiler.The guarantee
operates from the date installation is
completed for the customer who is the
original user.
To maximise the benefit from our
guarantee we urge you to return the
reply-paid guarantee registration.
This does not in any way prejudice
your rights at Common Law. Such
rights between the customer and the
installer or supplier from whom the unit
was purchased remain intact.
Any component or part which becomes
defective during the guarantee period
as a result of faulty workmanship or
material whilst in normal use will be
repaired or replaced free of charge.
B.S. Codes of Practice
Standard Scope
BS 6891 Gas Installation.
BS 5546 Installation of hot water supplies for
domestic purposes.
BS 5449 Part 1 Forced circulation hot water systems.
BS 6798 Installation of gas fired hot water boilers.
BS 5440 Part 1 Flues.
BS 5440 Part 2 Ventilation.
BS 7074 Expansion vessels and ancillary
equipment for sealed water systems.
BS 7593 Treatment of water in domestic hot water
central heating systems.
IMPORTANT - Care must be
exercised when lifting and handling
this product. Seek assistance where
appropriate and avoid stooping.
Protective equipment (e.g. gloves)
should be worn as necessary.

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3
1.0 Introduction 4
2.0 General Layout 5
3.0 Appliance Operation 6
4.0 Technical Data 7
5.0 Dimensions and Fixings 8
6.0 System Details 9
7.0 Site Requirements 12
8.0 Installation 17
9.0 Electrical 23
10.0 Commissioning the Boiler 25
11.0 Fitting the Outer Case 26
12.0 Servicing the Boiler 27
13.0 Changing Components 29
14.0 Short Parts List 36
15.0 Fault Finding 37
Section Page
Contents

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Potterton declare that no substances harmful to
health are contained in the appliance or used
during appliance manufacture.
NOTE: This appliance must be installed in
accordance with the manufacturer’s instructions
and the regulations in force, and only used in a
suitably ventilated location.
All systems must be thoroughly flushed and
treated with inhibitor (see Section 6.2).
Read the instructions fully before installing or
using the appliance.
1.1 Description
1. The Potterton Promax 15 HE and 24 HE are gas
fired room sealed fan assisted condensing central
heating boilers.
2. The maximum output of the Potterton Promax 15
HE is 52,000 Btu/hr. The maximum output of the
Potterton Promax 24 HE is 75,000 Btu/hr. Both
boilers automatically adjust their outputs down to
30,000 Btu/hr according to the system load.
3. It is designed for use on Natural Gas (G20).
4. The boiler is suitable for fully pumped open
vented central heating and domestic hot water
systems and sealed systems.
5. A label giving details of the model, serial number
and Gas Council number is situated on the top of
the outercase (Fig. 1).
6. The boiler data badge is positioned on the air
box door (Fig. 2).
7. The boiler is intended to be installed in
residential / commercial / light industrial E.M.C.
environments on a governed meter supply only.
8. The boiler must be installed with one of the
purpose designed flues such as the standard
horizontal flue kit, part no236921.
1.2 Important Information
This product contains Refractory Ceramic Fibres
(R.C.F.) which are man-made vitreous silicate fibres.
Excessive exposure to these materials may cause
temporary irritation to eyes, skin and respiratory tract.
Care must be taken when handling these articles to
ensure the release of dust or fibres is kept to a
minimum.
To ensure that the release of fibres from these articles
is kept to a minimum, during installation and servicing
it is recommended that a H.E.P.A. filtered vacuum is
used to remove any dust, soot or other debris
accumulated in and around the appliance. This should
be performed before and after working on the
installation.
It is recommended that any replaced item(s) are not
broken up but sealed within heavy duty polythene
bags and clearly labelled “R.C.F. waste”. This is not
classified as “hazardous waste”and may be disposed
of at a tipping site licensed for the disposal of
industrial waste.
Protective clothing is not required when handling
these articles but it is recommended that gloves are
worn and the normal hygiene rules of not smoking,
eating or drinking in the work area are followed and
always wash hands before eating or drinking.
1.0 Introduction
4
Fig. 1
Data Badge
Air Box Door
Fig. 2
“Benchmark” Log Book
As part of the industry-wide “Benchmark”initiative all Potterton boilers now
include an Installation, Commissioning and Service Record Log Book.
Please read the Log Book carefully and complete all sections relevant to
the appliance and installation. These include sections on the type of
controls employed, flushing the system, burner operating pressure etc.
The details of the Log Book will be required in the event of any warranty
work. Also, there is a section to be completed at each subsequent regular
service visit. The Log Book must be left with the user.
Label

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2.0 General Layout
5
2.1 Layout (Figs. 3,4 & 5)
1. Wall Plate
2. Flue Elbow
3. Heat Exchanger
4. Burner
5. Air Box
6. Fan Protection Thermostat
7. Fan Assembly
8. Condensate Trap
9. On/Off/Lockout Reset Switch
10. Gas Tap
11. Gas / Air Ratio Valve
12. Electronics Housing
13. Transformer
14. Flow Pipe Connection
15. Return Pipe Connection
16. Flow Temperature Safety Thermostat - Black
17. Flow Temperature Thermistor - Red
18. Flow Switch (dry fire protection)
1
2
3
4
5
6
7
9
8
10
11
12
13
17 16
14
15
18
Fig. 4
Fig. 3
Fig. 5
2.2 Optional Extras
KIT PART No
FLUE EXTENSION KITS (110/70)
Flue Extension 0.25M 241692
Flue Extension 0.5M 241694
Flue Extension 1M (Use two kits for 2M etc.) 241695
Flue Bend x 2 - 45°(Reduce overall length of flue
by 0.5m when fitting this bend) 241689
Flue Bend - 90°(Reduce overall length of flue
by 1m when fitting each bend) 241687
VERTICAL FLUE (110/70)
Vertical Flue Terminal 242802
Vertical Boiler Connection 242886

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3.0 Appliance Operation
6
3.1
1. Switched Live On: When the switched live
switches on pump overrun occurs.
2. Pump Overrun: The pump is on while the fan,
spark generator and gas valve are off. If at any
stage during pump overrun the flow temperature
is less than the set point and the flow switch is
made then fan purge occurs. After 1 minute of
pump overrun anti-cycle occurs.
3. Fan Purge: The pump and fan are on while
the spark generator and gas valve are off. After 5
seconds ignition occurs.
4. Ignition: The pump, fan, spark generator and
gas valve are on. If a flame is detected then
burner on occurs. If a flame is not detected within
5 seconds and less than 5 ignition attempts have
been made then fan purge occurs. If a flame is
not detected within 5 seconds and 5 ignition
attempts have been made the ignition lockout
occurs.
5. Burner On: The pump, fan and gas valve are
on while the spark generator is off. Flow
temperature is controlled by varying the fan
speed (and thereby the gas rate) to achieve
optimum operation. If the flow temperature is
greater than the set point then pump overrun
occurs. If the TRVs all shut down then anti-cycle
occurs.
6. Anti-cycle: The pump, fan, spark generator
and gas valve are switched off. After 3 minutes
pump overrun occurs.
7. Ignition Lockout: The pump, fan, spark
generator and gas valve are switched off. The
boiler can only be reset by manually using the
thermostat knob.
Mains On.
Flow
temperature less
than set point and flow
switch made ?
YES
5 second
Fan Purge.
Flame Detected ?
Burner On. Ignition
Lockout.
5 second
Ignition Period.
All TRVs
shut down ?
Flow temperature
greater than set
point ?
Ignition done and
5 attempts made ?
Ignition done
and less than 5
attempts made ?
Pump Overrun
Anti-cycle.
Pump Overrun
for 1 minute ?
YES
YES
YES
YES
YES
YES

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Appliance Category CAT I2H
4.0 Technical Data
7
Horizontal
Flue Terminal Diameter 110mm
Dimensions Projection 150mm
Outercase Dimensions
Overall Height Inc Flue Elbow - 750mm
Casing Height - 600mm
Casing Width - 390mm
Casing Depth - 320mm
Weights kg lb
Packaged Boiler Carton 40.7 89.6
Packaged Flue Kit 3.6 8.0
Weight Empty 38.2 84.1
Installation Lift Weight 31.5 69.3
Connections
Gas Supply - 1/2in BSPT
Central Heating Flow (HE15) - 28mm
Central Heating Flow (HE24) - 28mm
Central Heating Return (HE15)- 28mm
Central Heating Return (HE24)- 28mm
Condensate Drain - 1 in BSP
Recommended System
Temperature Drop
Normal 11°C20°F
Condensing 20°C36°F
Heat Input (see note) Max Min
15 HE kW 16.88 10.2
Btu/hr 57,600 34,840
24 HE kW 24.50 10.2
Btu/hr 83,600 34,840
Heat Output
(Non Condensing 70°C Mean Water Temp)
Max Min
15 HE kW 15.24 9.14
Btu/h 52,000 31,180
24 HE kW 22.0 9.14
75,000 31,180
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption 80W
External Fuse Rating 3A
Internal Fuse Rating (BS 4265)
Fuse (2) 4 AT (Control Board)
Fuse (3) 2 AT (Ignition Board)
Max Gas Rate (Natural Gas)
(After 10 Mins)
Btu/hr 75,000 52,000
m3/h 2.31 1.64
ft3/h 83.3 52.1
Inlet Pressure at Gas Valve (Natural Gas)
Min 18.1 mbar
Max 22.5 mbar
(see Section 10.1)
Injector (Natural Gas)
6.3mm Diameter
Clearances
Both Sides 5mm Min
Above Casing 200mm Min
Below Casing 130mm Min
Front (For Servicing) 500mm Min
Front (In Operation) 5mm Min
0 10203040
20
40
60
80
100
120
140
160
180
200
220
Water Flow Rate (litres/min)
Pressure Drop (mbar)
0.8
1.7
2.5
3.3
4.2
5.0
5.8
6.6
7.5
8.3
9.1
Pressure Drop (in wg)
Hydraulic Resistance Chart
Appliance Type C13 C33
Nox Class 5
Heat Output
(Condensing 40°C Mean Water Temp)
Max Min
15 HE kW 16.49 10.1
Btu/h 56,260 34,520
24 HE kW 23.8 10.1
81.200 34,520
Water Content
litres 2.6
pints 4.6
Static Head
max 30 metres (100 ft)
min 1 metre (3.25 ft)
Low Head 0.2m (8 in) min
System Detail
fully pumped open vented & sealed systems
Gas Connection RC1/2(1/2in BSPT)
Controls
installer preset boiler thermostat, safety
thermostat, flow switch, electronic flame
sensing,temperature protection thermostat
& condensate blockage sensor
The efficiency is
Promax 15 HE - 91.3%
Promax 24 HE - 91.0%
This value is used in the UK Government’s
Standard Assessment Procedure (SAP) for
energy rating of dwellings. The test data from
which it has been calculated has been
certified by 0086.
SEDBUK Declaration For
Potterton Promax 15 HE & 24 HE

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5.0 Dimensions and Fixings
8
DIMENSIONS
A600mm
B320mm
C390mm
D125mm ØMin.
E150mm
F125mm
SIDE FLUE (left and right)
For every 1m of horizontal flue
length, the clearance above the
top of the flue elbow should be
55mm to incorporate the 3°
(1 in 20) fall in the flue from the
terminal to the elbow.
The 3°(1 in 20) fall provided by
the elbow is to allow condensate
to run back to the boiler, for
disposal through the condensate
discharge pipe.
Flue length (Y)
up to 1m
1m - 2m
2m - 3m
Clearance (X)
55mm
110mm
165mm
360°Orientation
Tube Ø110mm
DC
B
A
E
F
Y
3°
(1 in 20)
X
3°
(1 in 20)
Fig. 6
Fig. 7

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6.0 System Details
9
6.1 Water Circulating Systems
1. The appliance is suitable for use with open vent
fully pumped systems and sealed systems .
The following conditions should be observed
on all systems:
•The static head must not exceed 30m (100ft)
of water.
•The boiler must not be used with a direct
cylinder.
•Drain cocks should be fitted to all system low
points.
•All gas and water pipes and electrical wiring
must be installed in a way which would not
restrict the servicing of the boiler.
•Position isolating valves as close to circulating
pump as possible.
•It is recommended that the return pipe is fitted
with an automatic air vent as close to the boiler
as is practical.
NOTE: Full TRV Systems (refer to section 6.4)
Where all the radiators are controlled by TRV’s
then pump protection will be required. This can be
done by either of the options opposite (see Fig A &
B). The option shown in Fig. A should only be
used on a full TRV system without a bypass.
Fig. B shows a system with a bypass that must
be capable of allowing a flow of at least 3 l/min.
6.2 Treatment of Water Circulating
Systems
•All recirculatory water systems will be subject to
corrosion unless an appropriate water treatment
is applied. This means that the efficiency of
the system will deteriorate as corrosion sludge
accumulates within the system, risking damage
to pump and valves, boiler noise and circulation
problems.
•When upgrading existing systems that exhibit
evidence of sludging, it is advisable to clean the
system prior to treatment in order to remove any
sludge and reduce the likelihood of these
deposits damaging new components.
•When fitting new systems flux will be evident
within the system, which can lead to damage of
system components.
•All systems must be thoroughly drained and
flushed out. The recommended flushing and
cleansing agents are Betz-Dearborn Sentinel
X300 or X400 and Fernox Superfloc Universal
Cleanser which should be used following the
flushing agent manufacturer’s instructions.
•System additives - corrosion inhibitors and
flushing agents/descalers should be suitable for
aluminium and comply to BS7593 requirements.
The only system additives recommended are
Betz-Dearborn Sentinel X100 and Fernox-Copal
which should be used following the inhibitor
manufacturer’s instructions.
Failure to flush and add inhibitor to the
system will invalidate the appliance warranty.
•It is important to check the inhibitor
concentration after installation, system
modification and at every service in accordance
with the manufacturer’s instructions. (Test kits
are available from inhibitor stockists.)
•For information or advice regarding any of the
above contact the Potterton Helpline.
Boiler
No demand
for hot water
Central
heating
load
All TRV’s shut down
(boiler flow switch
causes pump to stop)
Live feed
to pump
Switch live from
programmer, etc.
S/L N P/F
Fig. A Wiring to the pump feed connection of boiler
Fig. B Providing a 3 l/min bypass
Boiler
No demand
for hot water
Central
heating
load
All TRV’s shut down
(pump continues
around bypass)
Switch live from
programmer,
room stat, etc.
S/L
junction
S/L N P/F 3 l/min
bypass
Boiler
Connections
Boiler
Connections
NOTE: This boiler does not require a bypass.
This boiler does not require a permanent live.
These diagrams only refer to pump protection for fully TRV’d systems.

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6.0 System Details
10
6.3 Pipework
1. The sizes of flow and return pipes from the
boiler should be determined by normal methods,
according to the requirements of the system. The
connection to the boiler is 28mm (compression).
2. Due to space requirements within the boiler
outercase, pipework should comprise of solder
fittings.
3. A 20 °C (36°F) drop in temperature across
the system is recommended for condensing
boilers. Existing radiators may be oversized and
so allow this, but where radiator sizing is marginal
it may be advisable to retain a system temperature
drop of 11°C (20°F).
4. In systems using non-metallic pipework it is
necessary to use copper pipe for the boiler Flow
and Return. The copper must extend at least 1
metre from the boiler and include any branches
(Fig. 7a).
6.4 System Controls
1. For optimum operating conditions, the heating
system into which the boiler is installed should
include a control system.
2. Such a system will comprise of a timer control
and separate room or cylinder thermostats as
appropriate.
3. The boiler should be controlled so that it
operates on demand only.
4. Operation of the system under control of the
preset boiler thermostat & TRV’s only does not
produce the best results.
6.5 Low Head Installation
1. Using a close couple arrangement the minimum
head is as shown in the diagrams (Figs. 8 & 9)
subject to the following conditions:
a) The pump being adjusted to give an 20oC
drop across the boiler.
b) The pump must be fitted on the flow.
c) The pump must be fitted in accordance with
the pump manufacturer's instructions.
d) The open vent pipe must be taken up from a
tee in a horizontal section of the flow pipe.
An alternative Low Head Installation (Fig. 10)
2. For heads below 400mm then a combined vent
and feed pipe may be connected. This must be a
minimum of 22mm diameter. It is recommended
that an air separator is fitted when using a
combined feed and vent pipe.
6.6 Thermal Stores
1. The Promax 24 HE is suitable for fitting with a
Thermal Store, for details please contact
Technical Enquires (08706 049 049). The Promax
15 HE is not suitable for fitting with a thermal
store.
Typical Low Head Installation
If Conditions Require,
This System Possible
Alternative Low Head Installation
Boiler
500mm
45°
22mm
Open Vent
1000mm
Min
150mm
Max
15mm
Cold
Feed 400mm
Min Head
Return
Pump Flow
Boiler
500mm
45°
22mm
Open Vent
400mm
Min Head
1000mm
Min
Automatic
Air Vent 15mm
Cold
Feed
150mm
Max
Return
Pump
Flow
Return
Pump
Flow
Boiler
200mm
Min
Air
Separator
22mm
Feed & Vent
Pipe
Fig. 8
Fig. 9
Fig. 10
Boiler
Flow
Return
Copper
0.5m
Copper
1m
Copper
0.5m
Fig. 7a