page no. 30 of 44
HEMNVx & HEMSL Range Users, Installation & Servicing Instructions Doc Ref M103 issue 3.6 Mar 2020.
HEM units should be serviced once per year.
It is law that all gas appliances are installed,
adjusted and, if necessary, converted by
qualified persons* in accordance with the
current issue of the above regulations.
Failure to install appliances correctly can lead to
prosecution. It is in your own interests and that of safety
to ensure that the law is complied with.
* Gas Safe Registered Engineer.
WARNING: Always switch off and disconnect
electricity supply and close the gas service
valve before carrying out any servicing work
or replacement of failed components.
The appliance manufacturer must be
consulted before replacing parts other than
those specified or recommended in the
servicing instructions.
Additional care must be taken if external
units are serviced in wet conditions.
Consideration must be given to additional
requirements to maintain a safe working
environment e.g. Weatherproof covers.
Full maintenance should be undertaken not less than once
per year by a qualified person.
No 'specialised 'tools will be required to carry out this
service.
A fault finding guide is given in section 3.1 to aid servicing.
After any servicing work has been complete, or any
component replaced, the air heater(s) must be fully
commissioned and tested for soundness as described in
Section 2.6.
1. In addition it is advisable to check the gas rate using the
gas meter dial pointer. Ensure that no other appliances
supplied through the meter are in operation.
2. If required, after checking or setting the burner
pressures, the CO2 content in the flue gases can be
checked by sampling in the first section of flue fitted to
the flue outlet of the unit. Nominal CO2 values are given
for guidance in the table at the bottom of the previous
page.
3. Turn on the main burner as before and test for gas
soundness around pressure test joint using a leak
detection fluid e.g. soap solution. Replace access panel.
1. To measure the flame current connect a multimeter
capable of measuring micro amps as shown in the
following diagram.
2. Minimum current reading is 0.5µA and normal value
should be 1.5µA or higher.
Flame Current
Measurement
1. Close the gas service tap and ensure that the gas valve
is heard to close within 1 second and that the lockout light
is illuminated. Note that the heater may attempt five
re-ignitions before going to lockout. Open the gas service
tap and reset the unit from lockout.
2. Check that the room thermostat and all automatic
controls are operating satisfactorily.