The following installation manuals are available for the HCH range:
Ambirad VCH-HCH Mk1 Gas - Installation Manual - October 1998 - https://www.reznor.co.uk/wp-content/uploads/2023/12/AmbiRad-VCH-HCH-Installation-Manual-Mk1-Gas-EN-1998-10-9810VCGAMEN.pdf
Ambirad VCH-HCH Mk1 Oil - Installation Manual - July 1998 - https://www.reznor.co.uk/wp-content/uploads/2023/12/AmbiRad-VCH-HCH-Installation-Manual-Mk1-Oil-EN-1998-07-9807VCOAMEN.pdf
Ambirad VCH-HCH Mk2 Gas - Installation Manual - August 2004 - https://www.reznor.co.uk/wp-content/uploads/2023/12/AmbiRad-VCH-HCH-Installation-Manual-Mk2-Oil-EN-2004-08-0408-CHOAMEN.pdf
Ambirad VCH-HCH Mk2 Oil - Installation Manual - February 2008 - https://www.reznor.co.uk/wp-content/uploads/2023/12/AmbiRad-VCH-HCH-Installation-Manual-Mk2-Oil-EN-2008-02-0802-CHOAMEN.pdf