andrews MAXXflo EVO CWH 150/302 Manual

Andrews. Built to perform.
Please read and understand these instructions before commencing installation and leave this manual with the customer for future reference.
M10419
MAXXfl o EVO
High effi ciency condensing stainless steel storage water heater
CWH 150/302
INSTALLATION AND MAINTENANCE MANUAL

General 2 MAXXfl o EVO 150/302
Blank Page

General 3 MAXXfl o EVO 150/302
Table of Contents
Ref Subject Page
1.0 General & Safety Information
1.1 Description of heater ...............................................................................
1.2 For whom is this manual intended? ........................................................
1.3 Symbols used in this guide .....................................................................
2.0 Safety
2.1 General safety .........................................................................................
2.2 Regulations and standards ......................................................................
2.3 UKCA & CE Marking ................................................................................
3.0 Technical Data
3.1 Technical data .........................................................................................
3.2 Product Fiche ..........................................................................................
3.3 Performance data ...................................................................................
3.4 General dimensions and connections .....................................................
3.5 System Schematic examples ..................................................................
3.6 Wiring diagrams ......................................................................................
4.0 Installation
4.1 Locating the heater .................................................................................
4.2 Removing the door and inner cover ........................................................
4.3 Cold water supply ...................................................................................
4.4 Unvented design .....................................................................................
4.5 Secondary return design (DHW circulation pump) .................................
4.6 Condensate disposal ...............................................................................
4.7 Flue systems and ventilation ...................................................................
4.8 Maximum fl ue lengths .............................................................................
4.9 Gas connections ......................................................................................
4.10 Electrical & communication connections .................................................
5.0 Commissioning
5.1 Filling and removal of air .........................................................................
5.2 Commissioning of heat engine ................................................................
5.3 Conversion to LPG .................................................................................
5.4 Frost protection and Legionella ...............................................................
5.5 Final checks and user handover ..............................................................
5.6 Fault fi nding .............................................................................................
6.0 Maintenance
6.1 Routine Inspection intervals & requirements ............................................
6.2 Removing and changing components .....................................................
6.3 Flushing / Descaling the heat exchangers .............................................
6.4 Component parts illustrations ....... ..........................................................
6.5 Recommended spares requirements ......................................................
6.6 Error codes ...............................................................................................
4
4
5
6
7
8
9
10
11
12
13
18
20
20
22
23
24
25
26
35
36
37
39
41
47
49
51
52
53
60
69
70
78
79

General 4 MAXXfl o EVO 150/302
1.1 DESCRIPTION OF HEATER
This Andrews Water Heaters MAXXfl o EVO is a gas fi red, low NOx, twin heat engine, cascading, direct fi red
water heater, with an integrated stainless steel tank.
Fully automatic electronic controls are integrated into the heater, with a wide range of control and sensor
options available. The controls also provides voltage free outputs for Enable, Burner On and fault indication.
Full BMS integration is available through the use of Modbus and optional protocol devices.
Access to the controls of the heater via the Internet and/or mobile phone app, is possible through an optional
web server device available from Andrews Water Heaters.
Each heat engine module consists of a stainless steel combustion chamber, premix burner, modulating fan,
gas valve, ignition and fl ame detection electrodes, water pressure sensor and a NTC fl ue sensor for safety
supervision.
Each heat engine module is equipped with NTC sensors for precise temperature control on fl ow and return
manifolds. Fully premixed, radiating, modulating burner, integrated with gas valve to deliver precise gas/air
mixture throughout the full modulation range.
Common combustion air intake manifold, takes air from boiler room (type B23 fl ue) or directly from outside
via a combined fl ue system (C13, C33, C53 & C63).
The safety and operation functions of each heat engine are managed by micro processor controlled circuit
boards, one for each heat engine. The upper controller also acts as the cascade master controller, modu-
lating the heat engines according to the demand, based on data from the systems sensors. Control is per-
formed using comparison parameters between the requested temperature and the global fl ow temperature.
C L:
When a demand is started (the sensor of the DHW tank is less than the set point of the DHW tank - Hyster-
esis), the heat engine is ignited quickly (in the case of the MAXXfl o EVO 150 the second heat engine starts
approximately 60 seconds after the fi rst heat engine ignition). The controls calculate the charge setpoint (fac-
tory standard is the setpoint of the DHW tank) and the heat engine(s) modulate the pump(s) and burner(s) so
that the charge temperature in the tank does not exceed the charge set point.
When the temperature at B3 sensor equals the set point of the DHW tank, the burner(s) are switched off dur-
ing operation and the control elements remain in stand-by until the heat demand is restored.
If the temperature of the DHW tank (B3 sensor) is less than the DHW setpoint - DHW hysteresis, the de-
mand will be restarted and the operation as described above will start again.
1.2 FOR WHOM IS THIS MANUAL INTENDED?
This manual is intended for the heating specialist who installs commercial / industrial heating plant and
equipment.
1.0 GENERAL & SAFETY INFORMATION

General 5 MAXXfl o EVO 150/302
1.3 SYMBOLS USED IN THIS GUIDE
DANGER!
Indicates serious danger to personal safety and life
DANGER of electric shock!
Indicates serious danger from electricity to personal safety and life
WARNING!
Very hot water can cause severe burns and in extreme cases death
CAUTION!
Indicates a potentially dangerous situation for the heater and the
environment
INFORMATION
Suggestions to assist the user in implementing instructions in this
guide
ADDITIONAL READING
Reference to additional information in other documents

Safety 6 MAXXfl o EVO 150/302
2.1 GENERAL SAFETY
SMELL OF GAS
If you smell gas - follow these safety instructions:
- Do NOT turn off or on any electrical switches (including light switches)
- Do NOT smoke
- Do NOT use the telephone
- DO evacuate persons away from the source of the gas smell
- DO close the main gas shutoff valve
- DO open all the windows and doors where the gas leakage has occurred
- DO inform the gas authority or a competent specialist as soon as possible
DANGER
This Andrews Water Heaters product has been designed and manufactured to comply with cur-
rent European standards of safety. However, following an improper use, dangers could arise
concerning the safety and life of the user or of other people, or damage could be caused to the
heater or other objects. This heater is designed to be used in a domestic hot water supply and
storage system. Any other use of this heater will be considered improper. Andrews Water Heat-
ers declines any responsibility for any damage or injuries caused by an improper use. In order to
use the heater according to its designed scope, it is essential to carefully follow the instructions
given in this guide.
DANGER
This heater is not intended for use by persons with reduced physical, sensory or mental capabili-
ties, or lack of experience and knowledge, unless they are given supervision or Instruction con-
cerning the use of it by a person responsible for their safety. Children under the age of 12 years
should not be permitted to use the heater.
DANGER
The installation, adjustment & servicing of this heater must be carried out by a competent person
and installed in accordance with current standards and regulations. Failure to correctly install or
maintain this heater could cause injury to persons or damage to property. The manufacturer shall
not be held liable for any such injury and / or damage.
DANGER
Do not store or use explosive or easily infl ammable material (such as petrol, paint or paper) in
the same room where this heater has been installed.
CAUTION
Water temperature over 50OC can cause burns and in severe cases, injury or death. Children,
the elderly and the physically or mentally disabled are most at risk from scald injury. Feel water
before bathing and showering. Temperature limiting devices such as mixing valves should be
installed whenever possible to ensure safe temperatures at hot water outlets.
CAUTION
This heater has been designed for use with G20 (natural gas) and G31 (liquefi ed propane gas)
and is manufactured to give an effi cient, safe and long service life. To ensure continued trouble-
free operation of this heater at maximum effi ciency, it is essential that correct installation, com-
missioning, operation and service procedures are carried out strictly in accordance with the
instructions given in this manual.
Only original parts and accessories from the manufacturer may be used on this heater. Using
non-approved parts may compromise the safety of the heater and invalidate any warranty.
In the event of failure and/or suspected faulty functioning of the heater. Switch off the heater and
contact a suitable qualifi ed technician. Do not attempt to make any repairs yourself, unless you
are suitably qualifi ed and competent to do so.
2.0 SAFETY

Safety 7 MAXXfl o EVO 150/302
CAUTION
If the water system is not in use for periods exceeding 14 days, there is an increased risk of
corrosion on all copper parts and an increase in bacterial growth. Follow the recognised measures
for Anti-legionella in section 5.4.2. to manage this risk
2.2 REGULATIONS AND STANDARDS
This heater must be installed in accordance with relevant Standard Specifi cations, Codes of Practice and cur-
rent Building Regulations, together with any special regional requirements of the Local Authorities, Gas under-
taking and Insurance Regulations for the Electrical Equipment of Buildings. The installation of this heater must
be in accordance with the relevant requirements of:
• Health and safety at work act 1974
• Building regulations 2010
• Electricity at work regulations 1989
• Management of health and safety at work regulations 1998
• Manual handling regulations 1992
• Water Supply (Water Fittings) Regulations 1999 (England and Wales)
• Water Supply (Water Fittings) Byelaws 2014 (Scotland)
• Water Supply (Water Fittings) Regulations 2009 (Northern Ireland)
• BS 7671 - Requirements for electrical installations, IET wiring, regulations
• BS 6644 - Specifi cation for the installation of Gas fi red hot water boilers for rated inputs between 70kW
(net) and 1.8 MW
• BS 7074-2 - Applications selection and Installation of expansion vessels and ancillary equipment for sealed
water systems.
• BS 6880:1 Code of practice for low temperature hot water heating systems of output greater than 45kW.
• BS 6880:2 Code of practice for low temperature hot water heating systems of output greater than 45kW.
• BS 6880:3 Code of practice for low temperature hot water heating systems of output greater than 45kW.
• CP 342:2 Code of practice for centralised hot water supply. Buildings other than individual dwellings.
• IGE/UP/1 - Strength testing/tightness testing/direct purging of industrial and commercial gas installations
• IGE/UP/2 - Installation pipework on industrial and commercial premises
• IGE/UP/10 - Installation of fl ued gas appliances in industrial and commercial premises.
• IGE/UP/16 - Design for Natural Gas installations on industrial and commercial premises with respect to
Dangerous Substances and Explosive Atmospheres Regulations (DSEAR)
CAUTION
These manufacturer’s notes must not be taken in any way as over-riding statutory obligations.

Safety 8 MAXXfl o EVO 150/302
CATEGORY: I2H
FLUE TYPES: B23,C13,C33,C53,C63
0063
-
22
NG ONLY ADJUSTED FOR G20 @ 20mbar
MODEL:
MAXXflo EVO
CWH 150/302 7800597
HEAT INPUT (GROSS) Q(Hs)= 151.0kW
HEAT INPUT (NET) Q(Hi)= 136.0kW
HEAT OUTPUT P= 148.2kW
CO2 MAX RATE 9.0% (± 0.2%)
This appliance may only be installed in a room which complies with the
appropriate ventilation requirements. Read the technical instructions before
installing this appliance.
CONDENSING APPLIANCE
MAX WORKING PRESSURE
9
bar
CAPACITY
300
Litres
POWER SUPPLY
230V ~ 50Hz, IP20,
359
W
PIN CODE
0558CU2236 / 0063CT3553
COUNTRIES OF DESTINATION UK:IE
Year: 2022 Serial
No: 123456789
Manufactured by Malvern Boilers Ltd, Malvern, WR14 1BW, for:
Baxi Heating UK Ltd, Coventry Road, Warwick, UK CV34 4LL
M10120A
0558-22
2.3 UKCA & CE MARKING
There is one data plate located on the heater. This is mounted on the outside of the heater (left hand side)
The UKCA marking documents of this heater confi rms compliance with the essential requirements of the
following Regulations:
• Regulation (EU) 2016/426 on appliances burning gaseous fuel, as brought into UK law
• Ecodesign for Energy-Related Products and Energy Information (Amendment) (EU Exit) Regula-
tions 2019 No. 539
• Electromagnetic Compatibility Regulations 2016 No. 1091
• Electrical Equipment (Safety) Regulation 2016 No. 1101
KEY
1 Type approval designation
2 Gas type and pressure
3 Model Name
4 Heat, gas fl ow & CO² data
5 Technical data
6 Serial number and year
This manual is an integral and indispensable part of the heater and it is suggested that
this manual is kept in a safe place for future reference.
1
2
3
4
5
6

Technical Data 9 MAXXfl o EVO 150/302
3.0 TECHNICAL DATA
3.1 TECHNICAL DATA
Product name CWH
150/302
Daily electricity consumption Qelec kWh 0.221
Declared load profile XXL
Sound power level, indoors LWA dB 66
Daily fuel consumption Qfuel kWh 24.619
Emissions of nitrogen oxides NO Xmg/kWh 36
Weekly fuel consumption with smart controls Qfuel, week, smart kWh -
Weekly electricity consumption with smart controls Qelec, week, smart kWh -
Weekly fuel consumption without smart controls Qfuel, week kWh -
Weekly electricity consumption without smart controls Qelec, week kWh -
Storage volume Vl300
Mixed water at 40 °C V40 l∞
Harmonised standards applied
Specific precautions that shall be taken when the water
heater is assembled, installed or maintained:
EN: 13203-2
Before any assembly, installation or
maintenance the installation and
operation manual has to be read
attentively and to be followed
MAXXflo EVO

Technical Data 10 MAXXfl o EVO 150/302
3.2 PRODUCT FICHE
Product name
CWH
150/302
Declared load profile XXL
Water heating energy efficiency class ----
Water heating energy efficiency ηwh % 97
AEC kWh (1) 48
AFC GJ (2) 19
Thermostat temperature setting ᵒC 58
Sound power level LWA indoors dB 66
Ability to off-peak hours functioning(3) Yes
Enabled smart control settings(4) -
(1) Electricity
(2) Fuel
(3) If applicable
Annual energy consumption
Other load profiles for which the water heater is suitable to
use and corresponding water heating efficiency and annual
electricity consumption(3)
(4) If smart control setting value is "1", the water heating energy efficiency
and annual electricity / fuel consumption only relate to enabled smart control
settings
MAXXflo EVO

Technical Data 11 MAXXfl o EVO 150/302
3.3 PERFORMANCE DATA
PERFORMANCE Unit 150/302
Q Maximum Heat Input net (gross) kW 135.0 (149.9)
Q Minimum Heat Input net (gross) kW 29.0 (32.2)
Output Max (Min) kW 147.2 (31.5)
V Maximum Gas Consumption G20 / G31 m3/h 13.7 / 5.6
Flue gas temperature max (70OC Anti-legionella) oC90
CO2 at max output G20 / G31 % 9.0 / 9.8
CO at max output ppm 100
NOx emission GCV mg/kWh 36.0
NOx Class class 6
Sound level (EN15036-1 Average @ 1m) LAeq 66
HOT WATER
Tank capacity litres 300
Thermal Standby losses kWh/day 2.26
Recovery rate through 50oC l/hr 2,572
Recovery rate through 56oC l/hr 2,297
Approximate Heat up time T = 50oCminutes 7.2
Approximate Heat up time T = 45oCminutes 6.5
PMS Inlet / Operating pressure max (min) bar 9.0 (0.8)
In / Out connections BSP 1 1/2”
Water return connection BSP 1”
ELECTRICAL
Electrical supply voltage / Hz V / Hz 220 - 240 / 50
Fuse rating on mains supply A 5
Insulation protection rating IP 20
Power consumption - standby W 5.5
Power consumption - maximum W 359
FLUE
Flue connection - single mm 130
Flue connection - concentric mm 130/200
Flue systems permitted type B23, C13, C33, C53, C63
Max fl ue equivalent length - open (B23) m 44
Max fl ue equivalent length - concentric (C13, C33) m 24
Max fl ue equivalent length - twin (C53) m 48
Flue gas volume @ minimum load m3/h 49.8
Flue gas volume @ maximum load m3/h 232
Flue gas mass @ maximum load kg/h 224
Maximum internal fl ue pressure @ 65OC Pa 370
Maximum condensation production l/h 20.0
OTHER CONNECTIONS
Gas BSP 1”
Condensate mm 41mm
Tank drain mm 22mm
WEIGHTS & CLEARANCES
Shipping weight kg 296
Weight empty kg 226
Weight full kg 539
Service clearance - rear mm 20mm
Service clearance - right mm 25mm
Service clearance - top mm 400mm
Service clearance - left mm 300mm
Service clearance - front mm 800mm

Technical Data 12 MAXXfl o EVO 150/302
3.4 GENERAL DIMENSIONS & CONNECTIONS
LH Side Inner Cover Front Door
REMOVABLE PLATE
FOR TANK CONNECTION
INSPECTION (INSIDE UNIT)
TANK DRAIN (INSIDE UNIT)
22mm ISOLATION VALVE
T&P VALVE EXIT
495
1154
USER DISPLAY
POWER & RESET
SWITCHES
671
MCWS
1.5" BSP (m)
SECONDARY
RETURN
1" BSP (m)
MULTIPLE CABLE
ENTRY POINT
DHW
1.5" BSP (m)
602
TANK INSPECTION
HATCH
CHECK VALVE
301
9191
209
172
TANK SENSOR
WELL ACCESS
PANEL
DATA LABEL
913
1983
264
602
203
97
CONDENSATE
CONNECTION
41mm
60
259
300
391
128
GAS INLET
1" BSP
2x TP VALVES - 28mm
CONCENTRIC FLUE/AIR
130mm/200mm
REMOVABLE AIR DUCT
SPIGOT PLATE
CONDENSATE
TRAP
(2 PER UNIT)
2008 - REMOVABLE AIR DUCT SPIGOT FOR LOWER DOOR CLEARANCE
1998 - MINIMUM HEIGHT
REMOVABLE
AIR DUCT SPIGOT
718

Technical Data 13 MAXXfl o EVO 150/302
EXAMPLE 1: SINGLE MAXXfl o EVO (SCHEMATIC)
EXAMPLE 2: PARALLEL MAXXfl o EVO (SCHEMATIC)
3.5 SYSTEM SCHEMATIC EXAMPLES
B39
Q4
MAXXfl o EVO
B39
Q4
MAXXfl o EVO MAXXfl o EVO
Maximum circulation rate Q4 pump
Model MAXXfl o EVO
150
Flow (m3/h) 1.8

Technical Data 14 MAXXfl o EVO 150/302
Refer to “Controls Operating Instruction Manual for greater detail of the Anti-legionella function
setup
EXAMPLES 1 & 2: SINGLE AND PARALLEL MAXXfl o EVO (SETUP)
Menu Parameter Settings
DHW 1647
Legionella function
circulation pump
If the function is turned OFF, circulation pump Q4 will be switched OFF while the “Legionella”
function is performed (anti-legionella action performed on tank only).
If the function is turned ON, circulation pump Q4 is switched ON while the “Legionella” func-
tion is performed (anti-legionella action performed on DHW system).
1660
Pump release
Set desired option for activation of the DHW circulation pump, normally either activated with
time program 4 (DHW) or independently of DHW via time program 5
1661
Pump cycling
When switched on, the circulation pump Q4 will cycle on and off during the activation period
(on for 10 minutes then off for 20 minutes repeatedly).
Where B39 sensor has been installed this function will become active only once the circula-
tion setpoint has been achieved
1663
Circulation setpoint
When B39 sensor is installed on the DHW distribution return pipe, the heater controller will
monitor the return temperature during the activation time of the circulation pump Q4. When-
ever the temperature acquired by the sensor falls below the circulation setpoint, circulation
pump Q4 will be active until the setpoint has been exceeded (minimum pump run time is 10
minutes).
During a legionella cycle operation the temperature at the sensor can be used to adjust the
dwell time, ensuring that the entire DHW system reaches the legionella setpoint for the total
dwell time length set. The dwell time counter is not started until the temperature at the sensor
reaches legionella setpoint.
Main related parameter settings:
3.5 SYSTEM SCHEMATIC EXAMPLES (CONTINUED)
(
/13(/1
12

1&
&2 12 1&
&2 12 1&
&2
Q4 DHW
circulation
pump
1 amp max
(supplied by others)
B39
DHW return
sensor kit
(optional)
p/no: 7720071

Technical Data 15 MAXXfl o EVO 150/302
EXAMPLE 3: MAXXfl o EVO & BUFFER SS300-10 (SCHEMATIC)
3.5 SYSTEM SCHEMATIC EXAMPLES (CONTINUED)
Q4
ST1
K21
B39
AGU 2.5
MAXXfl o EVO
BUFFER
SS300-10

Technical Data 16 MAXXfl o EVO 150/302
EXAMPLE 3: MAXXFLO EVO & STORAGE TANK (SCHEMATIC)
Menu Parameter Settings
Confi guration 6020 Set function of extension module 1 to “Multifunctional”
6030 Set Relay Output QX21 module 1 to “dT controller 1 K21”
6041 Set sensor input BX22, module 1 to “Special temperature sensor 1”
General func-
tions
5570 Factory setting : Not used
5571 Factory setting: “- 1.5OC” - When BUFFER SS300-10 tank temperature is 0.5OC below
MAXXfl o EVO tank temperature K21 pump will be turned off .
5572 Factory setting: “3.0OC” - When BUFFER SS300-10 tank temperature is less than 2.0OC
below MAXXfl o EVO tank temperature K21 pump will be turned on.
5573 Factory setting : “DHW sensor B3”
5574 Factory setting : “Special temperature sensor 1”
5575 Factory setting : 30 seconds - Represents the minimum time that K21 pump will be activated
even if parameter 5571 conditions are met.
Related settings table (in addition to example 1 table)
3.5 SYSTEM SCHEMATIC EXAMPLES (CONTINUED)
(
+
0
%;
%;
8
0
0RGXOH1R
/ 1
4;
4;
4;
1
1
(
/13(/1
12

1&
&2 12 1&
&2 12 1&
&2
Q4 DHW
Circulation
pump
1 amp Max
(supplied by
others)
Buff er SS300-10
ST1 10k (B3977)
Tank sensor
K21 Transfer pump
1 amp Max
(Supplied by others)
AGU2.5 Expansion module
(supplied with Buff er SS300-10)
B39
DHW return
sensor kit
(optional)
p/no: 7720071

Technical Data 17 MAXXfl o EVO 150/302
EXAMPLE 4: BMS CONNECTIONS
3.5 SYSTEM SCHEMATIC EXAMPLES (CONTINUED)
BMS
/13(/1
12

1&
&2 12 1&
&2 12 1&
&2
Modbus
Enable
Fault
Flame (top burner)
Flame (bottom burner)
A+B- REF

Technical Data 18 MAXXfl o EVO 150/302
3.6 WIRING DIAGRAM (MAXXfl o EVO 150 kW MODEL)
PCB1
+
0
%;
%;
8
0
0RGXOH1R
/ 1
4;
4;
4;
1
1
0RGEXV
5HPRWHHQDEOH
YROWIUHH
)ODPH
LQGLFDWRU
9
+]
$
4
'+:
SXPS
)DXOWLQGLFDWRU
/3%
A+ B-
REF
DB/CL+
MB/CL-
/LYH
1HXWUDO
/LYH
(DUWK
1HXWUDO
%
'+:
UHWXUQ
WHPS
)ODPH LQGLFDWRU
/13(/1
12

1&
&2 12 1&
&2 12 1&
&2

Technical Data 19 MAXXfl o EVO 150/302
PCB2
3.6 WIRING DIAGRAM (MAXXfl o EVO 150 kW MODEL)

Installation 20 MAXXfl o EVO 150/302
The location selected for installation of the heater must allow the provision of a satisfactory fl ue, an ad-
equate air supply (for type B23), a drain and be well illuminated. A purpose built plant room or compartment is
strongly recommended.
If a purpose built plant room is not available, measures should be taken to protect the heater from damage
and prevent any extraneous matter from being stored on or around the heater. See BS 6644 Clauses 4, 5
and 6 for details.
There must be easy access to the plant room and heater at all times. The heater must be located in an area
where leakage from the tank, water connections or the combined temperature and pressure safety valve will
not result in damage to the area adjacent to it. When such locations cannot be avoided, a suitable drain tray
must be installed under the heater. The drain tray must be no deeper than 38mm and must be 100mm wider
and longer than the heater. It should be piped to an adequate drain using 20mm (0.75in) diameter pipe,
angled for proper drainage.
Access must be provided to the front of the heater with adequate clearance for servicing and operation
(See 3.3) The fl oor on which the heater is installed must be fl at, level and of suffi cient strength to withstand
the weight of it when fi lled with water, and should satisfy the requirements of the Local Authority & Building
Regulations.
Ensure that the heater is isolated from the power supply.
Remove the single screw (A) on the left hand side of the door.
Release the two latches (B) by pulling on the back of the latch and lifting outwards.
Open the door, and detach the case earthing lead near the upper hinge (C). Lift the door upwards and
off its hinges. Place the door carefully against a wall, ensuring that it cannot fall over.
4.1 LOCATING THE HEATER
4.2 REMOVING THE DOOR AND INNER COVER
4.0 INSTALLATION
AB
C