Access is from the back via a removable panel towards the bottom.
RTFM you got with the heater (or which yo could have found on the Dimplex website:
Make a note of these (Download and save and put a copy on your backup drive as well)
http://www.dimplex.co.uk/assets/kb/operating_instructions/0/Club_&_Ritz_Instructions_-_Issue_2.pdf
http://www.dimplex.co.uk/assets/kb/self_help_guide_diagnostics/0/fires_and_surrounds.pdf
http://www.dimplex.co.uk/customer_support/downloads/index.htm?key_id=400683&search=CLB20L
XXX, November 2015
