WARNING:
Always switch off and disconnect
electricity supply, close the gas service valve or
turn off the oil supply before carrying out any
servicing work or replacement of failed compo-
nents.
4.1.1 General
Full maintenance should be undertaken not less than
once per year. After any servicing work has been com-
plete or any component replaced the air heater(s) must
be fully commissioned and tested for fuel tightness as
described in Section 2.5. Page 17
4.1.2 Burner Servicing/Maintenance
1. Refer to the burner instructions supplied with the
heater and complete the servicing/maintenance instruc-
tions therein. Note: In the case of gas burners ignore any
references in the burner supplement to the gas controls
assembly.
4.1.3 Heat Exchanger Cleaning
1. Removing the upper rear panel of the heater exposes
the heat exchanger rear clean out panel.
2. Removing the fan/limit thermostat(s) as described in
4.1.6.6.4, Page 25 disconnecting the flue and then
removing the upper front panel of the heater exposes the
heat exchanger front clean out panels. If the flue cannot
be disconnected removal of the side panels exposes the
upper front header side clean out plates.
3. Remove the nuts securing the clean out panel(s) as
appropriate and remove panel(s).
4. If heat exchanger baffles are fitted, withdraw them.
5. Brush through heat exchanger tubes and remove loose
material using a vacuum cleaner.
6. If it is necessary to also gain access to the combustion
chamber disconnect the fuel and electrical connections
from the burner. Remove the nuts securing the burner to
the heater and withdraw the burner from the burner tube.
7. Reassemble all components in reverse order. Note:
Replace any gaskets with new ones.
4.1.4 Fan Assembly
1. Remove the lower panels of the heater to gain access
to the fan section.
2. Inspect the fan blades to see that they are not dam-
aged and that there is no excessive build up of deposits
that could give rise to an imbalance. If necessary clean
the fan blades using a stiff brush and vacuum cleaner.
3. Replace panels accordingly.
4.1.5 Oil Filter (if applicable)
1. Release the securing bolt, or unscrew the filter bowl, to
access the filter.
2. Clean the filter or replace as deemed necessary.
3. Refit bowl ensuring that seals are correctly in place.
4.1.6 Replacement of Faulty
Components
4.1.6.1 Burner Components
1. Refer to the burner instructions supplied with the heater
for information regarding replacement of components
within the burner.
4.1.6.2 Gas Controls Assembly (if
applicable)
1. Remove the electrical connections from the gas control
block.
2. Release the nuts securing the inlet and outlet flanges to
the gas control block and lift out the gas control block. Fit
the replacement assembly in reverse order ensuring the
valve is correctly orientated =for the direction of gas flow.
4.1.6.3 Main Air Fan and Motor
Important: On 3ph heaters fitted with 3ph main
fan motors ensure that the fan direction of
rotation corresponds with the direction of rotation
arrow on the fan guard or case. If necessary
reverse the direction of rotation by interchanging
any two of the motor live leads at the terminal
strip in the electrical panel. Should it be neces-
sary to remove one or more of the fans for clean-
ing proceed as follows.
4.1.6.3.1 CPx 30 - CPx 120
Note: These heaters are fitted with direct drive
fan units.
1. Disconnect the fan motor electrical leads from
the terminal strip (Refer to wiring diagram
supplied with the heater)
2. Remove the two screws, one on each side of
the fan mounting flange, that secure the fan to the
fan shroud.
3. Remove the screws securing the heat
exchanger mounting frame to the fan shroud on
the side that the fan is going to be withdrawn.
4. Withdraw the fan from the slide rails.
5. Reassemble in reverse order.
4.1.6.3.2 CPx 150 - CPx 300
Note: These units are fitted with belt driven main
air fans.
1.Remove the lower side panel(s).
2. Release the motor mounting plate securing
screws and then remove the belt tension by
turning the tension adjustment screw anticlock
wise. Remove the fan belts.
3. Remove the screws securing the fan mounting
feet to the heater framework and remove the fan.
It may be necessary to re-orientate the fan within
the fan compartment and also to release the fan
shroud fixings in order to pass the fan through
the heater frame. On units with twin or triple fan
sets on a common fan shaft it will be necessary to
first remove the fan shaft.
4. Inspect the fan belts and if necessary replace
with new.
5. Replace components in reverse order.
6. Do not over tension the fan belts. There should
be approximately 15mm of deflection when
downward pressure is applied to the belt(s)
halfway between the motor and fan pulleys.
Fig 3 Fan belt tension setting
4.1.6.6.4 Fan / Limit Thermostat Hon-
eywell L4064B
NOTE:
Larger heaters have two fan and limit
thermostats fitted.
Either one will start the main fans and either one
will shut down the burner in the event of an over-
heat situation.
1. Squeeze the sides of the cover and remove
cover by pulling forward.
2. Release wiring from clamp terminals by push-
ing a small screwdriver into the clamp release
holes adjacent to the clamps.
3. Remove the 2 screws securing the thermostat
to the heater panel and withdraw thermostat.
4. Reassemble new unit in reverse order referring
to the heater wiring diagram to ensure correct
wiring location.
Important:
A replacement fan/limit thermostat
may have a brass link between the bottom fan
terminal and the bottom limit terminal (situated in
the slot between the two terminals). This
MUST
be removed, by breaking the link off using a pair
of thin nose pliers, before the replacement
thermostat is installed.
HEATING DIVISION
Hort Bridge
Ilminster, Somerset TA19 9PS
Tel: 01460 53535
Fax: 01460 52341
Every effort is made to ensure accuracy at time of going to press. However as part of our policy of continued product
improvement, we reserve the right to alter specification without prior notice.
Page 28 CPx Gas or Oil Cabinet Heater Range Issue 2.1 June 2014
Appendix A
Calculation Of Flue System Equivalent Resistance
The pressure resistance of the flue system (Pr) = 1.5 * [(PFF*H/D+SRF)Qm/Wm2] (pa)
Where H = Effective flue height in m
D = Internal Diameter of flue in m
PRF (
Pipe Friction Factor) = 0.118*(0.21147/D0.4)
Where D = Internal Diameter of flue in m
SRF (
Sum of individual resistance factors)
Typical resistance factors for individual components are as follows
Segmented 90° bend
0.5
45° Elbow
0.4
Cowl
1.0
Qm (
Mean Density of the column of exhaust gas in kg/m3) = 97000/(300*Tm)
Where the mean temperature of the column of exhaust gas (Tm) = 288+((Te-TL)/0.2)*(0.18)
Where
Te is the exhaust gas temperature in °C
TL is the external air temperature in °C
Wm (
Mean exhaust gas velocity in m/s = M/(A*Qm)
Where A is the cross sectional area of the flue in m2
M is the exhaust gas mass flow in kg/s which is as follows for the various units
CPx 30
0.018
CPx 150
0.125
CPx 45
0.027
CPx 175
0.14
CPx 60
0.035
CPx 200
0.145
CPx 90
0.050
CPx 250
0.16
CPx 120 0.080
CPx 300
0.2
