Johnson & Starley AQUAIR S-25 User guide

www.johnsonandstarley.co.uk
www.johnsonandstarley.co.uk
Johnson & Starley Ltd
Rhosili Road
Brackmills, Northampton
NN4 7LZ
Aquair Water To Air Space
Heaters
Aquair S-25
These instructions are to be left with the User
INSTALLATION, COMMISSIONING
& SERVICING INSTRUCTIONS
AQUAIRS-25
of Water to Air Space Heaters
Publication No. ZZ 1428-3
November 2021

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In the interest of continuous development Johnson and Starley reserve the right to change specification without prior notice.
Johnson and Starley prides itself on it’s ability to supply spare parts quickly and efficiently.
CONTENTS
1 Features 3
2 General Description 3
3 Building Standards & Regulations 4
4 Safety Information 4
Handling the Unit
Electrical Supply
5 Technical Data 4
6 Positioning & Preparation 5
7 Installation Instructions 5
Downflow Installation
Water Connections
Electrical Harness
8 Return Air System 5
9 Electrical 6
10 Circuit Diagram 6
11 Fan Performance 6
12 Operating Mode 7
High Temperature Mode
Low Temperature Mode
13 Commissioning 7
Setting Maximun Speed
Setting Minimum Speed
With Therimsta-stat Fitted
With No Thermista-stat Fitted
14 Servicing & Maintenance 7
Routine Maintenance
PCB Replacement
PCB Removal
Fan Removal
Heat Exchanger Removal
Air Filter Removal
15 Faulty Finding 8
16 Dimensions 10
17 Spares List 10
18 Exploded Diagram 11

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1. FEATURES
2. GENERAL DESCRIPTION
2.1 AQUAIR S is a water to air heat exchange unit with a heat output of 25kW (assuming a hot water supply at 80˚C
is available). Modairflow control is incorporated. A wire mesh filter is fitted as standard. The unit requires a supply
of hot water at a minimum temperature of 60°C. Water connections are left or right handed through knockouts
in the sides of the cabinet.
2.2 The air is drawn in through the air filter or Cleanflow air cleaner (if fitted) and the heat exchanger by a centrifugal
fan, and is discharged through the opposite end of the unit. A Summer Air Circulation switch (optional) provides
the facility to supply unheated air to the air outlets during warm weather. An external timer (not provided) will be
required if it is necessary to set the periods of operation.
2.3 The Aquair S Unit has been designed to allow downflow configuration only.
8
9
7
1
2
5
4
3
6
FIGURE 1. AQUAIR S-25 FEATURES
1 Mains Supply
2 Air Filter
3 Air Circulation Fan with EC Technology
4 PCB Control Board
5 Hot water return to heat source
6 Hot water flow from heat source
7 Flow Sensor
8 Heat Exchanger
9 Spigot Frame

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3. BUILDING STANDARDS & REGULATIONS
NOTE: Installation shall be in accordance with the following
• Building Standards (Scotland) (Consolidation) Regulations
• Building Regulations Part L
• The Water Fittings Regulations or Water byelaws in Scotland
• Model and Local Authority Byelaws
• BS 5720 Mechanical Ventilation and Air Conditioning in Buildings
• BS 7671 Institute of Electrical Engineers (I.E.E) Wiring Regulations
• Health & Safety Document No. 635.
• The Electricity at Work Regulations, 1989.
IMPORTANT: This appliance is CE certificated for safety and performance. It is important that no modifications are made
to this appliance, unless fully approved in writing by Johnson & Starley Ltd.
If in doubt please Ring Johnson & Starley Ltd on Telephone: [phone].
* The manufacturers instructions supplied must not be taken as overriding any statutory requirements.
4. SAFETY INFORMATION
4.2 HANDLING THE UNIT
4.2.1 The weight of the this appliance exceeds that recommended for a one-man lift. It will therefore be
necessary to gain assistance at times during the removal from its packaging and during installation
procedure. Manoeuvring the boiler may include the use of a sack truck and involve lifting, pushing and
pulling.
4.2.2 It should be noted that this appliance may contain sharp edges. Care MUST be taken when handling
the appliance to prevent injury. We advise the engineer to wear suitable P.P.E.
4.2.3 Once the appliance has been fired beware that certain parts will be hot to the touch.
4.2.4 Do not install flues during rain, high winds or in severe weather conditions.
4.1 ELECTRICAL SUPPLY
4.1.1 Ensure the mains supply voltage, frequency, number of phases and power rating comply with details
on the rating label.
4.1.2 All wiring must be in accordance with the appropriate standards.
4.1.3 Ensure safety regulations and practices are adhered to when installing and using this appliance.
5. TECHNICAL DATA
TABLE 1 ITEM S-25
Nominal Rated Output kW 25
Air on Temperature ˚C 20
Air off Temperature ˚C 67
Water Supply Temperature ˚C 80
Water Return Temperature ˚C 55
Water Flow Rate l/s 0.25
Air Volume m³/h 1584
Water Connections bsp ¾
Maximum Water Pressure Bar 3
Maximum Power Consumption W 530W
Dimensions mm H/W/D 1078 x 480 x 710
Return Air Frame mm 587 x 400
Electrical Supply A 230V, 50Hz, fuse rated at 3A
Weight kg 70kg

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6. POSITIONING & PREPARATION
6.1 The unit should be positioned to suit any duct work. Mount on a plenum, if necessary or frame strong enough
to to hold the unit, avoiding any strain being placed on associated pipe and duct work.
6.6 Once the position of the unit has been decided, make sure all extra ancillaries are installed ready for the units
installation. A list of the ancillaries is available by contacting Johnson & Starley Ltd, Tel: [phone].
6.2 Make sure all the electrical cables are in place.
6.3 It is important that the system is flushed thoroughly prior to installation. Failure to do so could result in the
appliance a blockage and cause damage to the system and reduce the efficiency. This MUST to comply with
the water treatment guidelines.
IMPORTANT: It is recommended that the water system be drained and flushed prior to the installation
of the unit. A strainer must be fitted upstream of the unit.
6.4 Clearance of 750mm is required at the front of the casing for servicing and replacement of the heat exchanger.
It is recommended that provision be made for complete removal of the unit.
6.5 Sufficient clearance must be provided for the assembly of ducting and pipework.
7. INSTALLATION INSTRUCTIONS
7.1 The Aquair S-25 appliance exceed the recommended weight for a
one-man lift as detailed in the Manual Handling Operations,1992
Regulations.
7.2 The once the unit has been unpacked unscrew the transit plate
from the base of the unit and discard.
NOTE: This unit could contain sharp edges and care MUST be taken
when handling.
7.3 DOWNFLOW INSTALLATION See Figure 2
7.3.1 Remove the filter cover to expose the two screw holding
the door in place. Remove the screws and gently pull and
lift the door off the unit.
7.3.2 Lift the appliance onto the plenum or base support and
position correctly. Seal the joint with the appropriate
sealing material.
7.3.3 The water connections to the unit should be by
compression fittings that are suitable for the duty and
isolation valves must be fitted to facilitate the removal of
the heat exchanger assembly.
7.3.4 If a return air duct is not to be fitted, the top of the unit
must be suitably guarded to prevent any blockage.
7.4 WATER CONNECTIONS
The water connections to the unit should be compression type fittings that are suitable for the duty of the
appliance. Isolation valves must be fitted to facilitate the removal of the heat exchanger assembly.
NOTE: Care must be taken with the heat exchanger matrix is fragile and is easily damaged.
7.5 ELECTRICAL HARNESS
Re-route the harness cable through the side knockout. Using the grommet attached, to seal the hole.
8. RETURN AIR SYSTEM
8.1 The return air system should be constructed of fire-resistant material. It is important that the correct size of return
air grilles and ducting is used. Refer to table below for return air duct size, flexible duct size and the return air
grille size at maximum output.
8.2 An adequate and unobstructed return air path is required from areas not served by a directly ducted return and to
which warm air is delivered. All such rooms should be fitted with relief grilles which have a free area of 0.0088m²/kW
(1in²/250Btu/h) of heat supplied to the room. The only exceptions are kitchens, bathrooms and WC.’s.
FIGURE 2. DOWNFLOW CONFIGURATION
SCREWS AIR FILTER
PLENUM
DOOR
FILTER COVER
KNOCKOUTS
KNOCKOUTS
TABLE 2 DUCT EQUIVALENT SIZE FLEXIBLE DUCT SIZE RETURN AIR GRILLE
S-25 600 x 400mm (23” x 16”) 508mm (20”) dia 4200cm² (in²)

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FIGURE 4. AQUAIR S-25 CIRCUIT DIAGRAM
FIGURE 3. FAN PERFORMANCE GRAPH
9. ELECTRICAL
9.1 The appliance is supplied with PVC sheathed, 3 core 0.75mm2csa rated at 6A, connected to a terminal block
and exiting through the casing at the top left hand front. The cable is suitable for a 230V 50Hz single phase
supply.
9.2 The means of isolating the appliance MUST be via a double pole switch with a contact separation of at least
3mm in both poles, and fused at 3A. If switched live is fitted, a triple pole switch should be used.
10. CIRCUIT DIAGRAM
11. FAN PERFORMANCE
COLOUR CODE
bn BROWN
bl BLUE
bk BLACK
g/y GREEN/YELLOW
r RED
w WHITE
or ORANGE
y YELLOW

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12. OPERATING MODES
12.1 HIGH TEMPERATURE MODE
12.1.1 For high temperature mode the J1 pins 1 + 2 has NO jumper.
12.1.2 With a thermista-stat connected (see note*), the fan will run when a water temperature of 60°C is
reached and stops when the water temperature falls to 42°C. The fan speed is controlled by the
thermista-stat demand.
12.1.3 With no thermista-stat connected, the fan will run when a water temperature of 44°C is reached, the
fan speed is controlled by the water temperature. The maximum fan speed reached when the water
temperature is at 60°C.
12.2 LOW TEMPERATURE MODE
12.2.1 For low temperature mode J1 has a jumper across pins 1 + 2.
12.2.2 With the thermista-stat connected, the fan will run when a water temperature of 33°C is reached and
stops when the water temperature falls to 20°C. The fan speed is controlled by the thermista-stat
demand.
12.2.3 With no thermista-stat connected, the fan will run when a water temperature of 22°C is reached, the
fan speed is controlled by the water temperature. The maximum fan speed reached when the water
temperature is at 32°C.
NOTE: Thermista-stat to be ordered separately.
13. COMMISSIONING
13.1 Ensure the heater is correctly fitted with water and all air vented from the flow and return circuits.
13.2 Switch on electrical supply.
13.3 Setting maximum speed.
Make a short across thermista-stat connections, if fitted, and adjust the fan speed as required, remove the short.
13.4 Setting minimum fan speed.
Make a short across the pipe sensor and adjusted the fan speed as required, remove short.
13.5 WITH THERMISTA-STAT FITTED
13.5.1 Turn up thermista-stat to call for heat.
13.5.2 Check for 230V on switch live out.
13.5.3 With the water at the required temperature ensure fan starts
13.5.4 Allow the system to warm up and check temperature rise across unit is 40°C.
13.5.5 Set water differential to 20°C using lock shield valve or equivalent.
13.5.6 Turn off thermista-stat and check there is NO 230V on switch live out.
13.5.7 Check fan stops when water cools to required temperature.
13.6 WITH NO THERMISTA-STAT FITTED
13.6.1 With the water at the required temperature ensure fan starts.
13.6.2 Allow the system to warm up and check temperature rise across unit is 40°C.
13.6.3 Set water differential to 20°C using lockshield valve or equivalent.
13.6.4 Check fan stops when water cools to required temperature.
14. SERVICING & MAINTENANCE
14.1 ROUTINE MAINTENANCE
IMPORTANT: Before carrying out any work on the unit, ALWAYS ENSURE THAT IT IS ISOLATED FROM
THE MAINS ELECTRICAL SUPPLY.
Remove the filter and unscrew the two retaining screws holding the front cover on the unit, gently pull it forward.
Maintenance should be carried out at least once per year.
14.1.1 Check that the heat exchanger airways are free from obstructions. If necessary, clean with a
vacuum cleaner from the air inspection panel, taking care to not damage the airways.
CAUTION: THE ELEMENTS OF THE HEAT EXCHANGER ARE VERY FRAGILE.
14.1.2 Check the condition of the external strainer, cleaning as necessary.
14.1.3 Check that the air filter is being regularly cleaned in accordance with the User’s Instructions.
14.2 PCB REPLACEMENT
Ensure that the electrical supply is switched off and isolated.

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There must be a link between
High Voltage terminals 1 &
6 and high voltage terminals
3 & 6. Make sure both links
are present
MAF STAT CONNECTED NOT CALLING FOR HEAT (BOILER NOT FIRING) WHEN MAF STAT ON MAXIMUM
NO
YES YES
NO
NO
YES
YES
YES
NO
YES
NO
NO
NO
NO
YES
YES
NO
Is there 230 ~ 250VAC across High Voltage terminals 2 & 4?
Is there 230 ~ 250VAC across High Voltage terminals 1 & 2?
Measure DC voltage (5.1V DC Max.) across Low Voltage terminals 3 & 4
Is measured voltage greater
than 4.7V
Is measured resistance
greater than 11K?
Is measured voltage greater
than 4.7V
Check pipe sensor and
connections. If sound, isolate
from mains & measure resistance
across plug J2 pins 5 & 6
Is measured voltage greater than 4.19V?
Is there an external clock fitted?
Measure DC voltage (5.1V DC
Max.) across Low Voltage
terminals 5 & 6
Check black wire of MAF stat
goes to Low Voltage terminal 3
and red wire of MAF stat goes to
low voltage terminal 4. Ensure all
connections are sound
Check clock is on & measure
output
Check for live supply into clock.
Replace clock if live is present
Is 230 ~ 250VAC present?
Check harness connections
to PCB. If all OK Replace
PCB
Remove MAF stat connections
and link Low Voltage terminals
TPV & 3. Is there 230 ~ 250VAC
across High Voltage terminals
2 & 4?
Open circuit between clock
out & High Voltage terminal
block 1
Unit mains
supply is
missing.
Check spur
e.g. fuse is
intact
Check
connections
to high voltage
terminals
2 & 3
Problem with switched live output going from High Voltage terminal 3 to
switch live of boiler
Is there 230 ~ 250VAC across High Voltage terminals 2 & 3?
15. FAULT FINDING
14.3 PCB REMOVAL
14.3.1 Disconnect the wiring at the PCB terminal block.
14.3.2 Release the 4 clips securing the PCB and withdraw the panel, disconnecting the fan supply lead at the
fan tray terminal block.
14.3.3 Reassembly or replacement is in reverse order.
14.4 FAN REMOVAL
14.4.1 Ensure that the electrical supply is switched off and isolated.
14.4.2 Disconnect the 2 inline connectors on the fan assembly.
14.4.3 Release the screws securing the fan and withdraw if from the location runners.
14.4.4 Refitment or replacement is in reverse order.
14.5 HEAT EXCHANGER REMOVAL
14.5.1 Ensure that the electrical supply is switched off and isolated.
14.5.2 Close the isolating valves and drain down the unit.
14.5.3 Release the clip and remove the heat exchanger and its associated pipework from the unit.
14.5.4 Refitment or replacement is in reverse order. Ensure that all air locks are expelled, and check for water
soundness.
14.6 AIR FILTER REMOVAL
14.6.1 Remove the filter cover.
14.6.2 Remove the two air filters out by sliding it from the front of the unit.

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FAN NOT OPERATING WHEN PIPE IS ABOVE 60°C
NOYES
YES
YES NO
YES
NO
NO
YES
NO
NO
Is there and external clock fitted or external mains room stat fitted?Is there and external clock fitted or external mains room stat fitted?
Check for mains going into fan plug
There must be a link between high voltage terminals 1 & 6 and high
voltage terminals 3 & 6. Make sure both links are present
There must be a link between High Voltage terminals 1 & 6 and high
voltage terminals 3 & 6. Make sure both links are present
Measure DC voltage (0 to 10V) within Low Voltage fan connector
(blue & yellow)
Make sure mains is present across high voltage terminals 1 & 2
and 3 & 4
Make sure mains is present across High Voltage terminals 1 & 2
and 2 & 3
Is measured voltage greater than 2V?
Check pipe and connections.
If sound, isolate from mains &
measure resistance across plug
J2 pins 5 & 6
Does the actual pipe temp.
match the approx. pipe temp.
for the measured voltage in
Table A?
Is measured resistance greater
than 11K?
Faulty fan
Faulty PCB
Check sensor is fitted correctly. If
it is then replace sensor.
Faulty PCB
PCB is not seeing sensor.
Confirm by measuring
sensor resistance. Replace
sensor if resistance is greater
then 28K.
YESYES
NO
In there 230 ~ 250 VAC across high voltage terminals 1 & 2?If there 230 ~ 250 VAC across High Voltage terminals 1 & 2?
Make sure mains is present across High Voltage terminals 2 & 3
Is the MAF stat connected?
Is fan now running?
Link out low voltage terminals 3 & 4.
Measure voltage across Low Voltage terminals 5 & 6
Is measured voltage greater than 4.7V DC?
Make sure clock or room stat supplies mains voltage to high voltage
terminals 1 & 2. No mains - no fan operation (except for summer vent)
DC VOLTAGE ACROSS
PIPE SENSOR APPROX. PIPE TEMP. °C DC VOLTAGE ACROSS PIPE SENSOR APPROX. PIPE TEMP. °C DC VOLTAGE ACROSS PIPE SENSOR APPROX. PIPE TEMP. °C DC VOLTAGE ACROSS PIPE SENSOR APPROX. PIPE TEMP. °C
3.24 10 2.13 33 1.26 56 0.73 79
3.19 11 2.08 34 1.23 57 0.71 80
3.14 12 2.04 35 1.20 58 0.70 81
3.09 13 1.99 36 1.17 59 0.68 82
3.04 14 1.95 37 1.15 60 0.66 83
2.99 15 1.91 38 1.12 61 0.65 84
2.94 16 1.87 39 1.09 62 0.63 85
2.89 17 1.83 40 1.07 63 0.63 86
2.84 18 1.79 41 1.04 64 0.60 87
2.79 19 1.75 42 1.02 65 0.59 88
2.75 20 1.71 43 0.99 66 0.58 89
2.70 21 1.67 44 0.97 67 0.56 90
2.65 22 1.63 45 0.95 68 0.55 91
2.60 23 1.59 46 0.92 69 0.54 92
2.55 24 1.56 47 0.90 70 0.53 93
2.50 25 1.52 48 0.88 71 0.51 94
2.45 26 1.49 49 0.86 72 0.50 95
2.40 27 1.45 50 0.84 73 0.49 96
2.36 28 1.42 51 0.82 74 0.48 97
2.31 29 1.39 52 0.80 75 0.47 98
2.26 30 1.35 53 0.78 76 0.46 99
2.22 31 1.32 54 0.76 77 0.45 100
2.17 32 1.29 55 0.75 78 TABLE A

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FIGURE 7. AQUAIR S-25 DIMENSIONS
16. DIMENSIONS
17. SPARES LIST
ITEM DESCRIPTION QTY S-25
1 Air filter 2 AQ25-0185005
2 Air circulation fan with EC technology 1 1000-0525980
3 PCB control board 1 1000-0526275
4 Temperature flow sensor 1 1000-0526505
5 Front Cover 1 AQ25-0199005
6 Heat exchanger 1 AQ25-0138005
7 Thermista-stat (not shown) 1 BOS01242

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18. EXPLODED DIAGRAM
1
2
5
3
6
4
SPIGOT FRAME
FAN SLIDER
SIDE
KNOCKOUTS
FLYING
LEAD
HOT WATER
FLOW FROM
HEAT SOURCE
HOT WATER RE-
TURN FROM HEAT
SOURCE
FIGURE 8. AQUAIR S-25 EXPLODED DIAGRAM

Johnson & Starley Ltd
Rhosili Road, Brackmills,
Northampton NN4 7LZ
[e-mail]
[e-mail]
[e-mail]
[e-mail]
Reception/Customer Service
01604 762881
In the interest of continuous developement Johnson & Starley reserve the right to change specifications without prior notice.