the amount of heat going out the exhaust is greater than the heat coming into the house can the exhaust be controlled in any way

Alma, August 2017

From the manual: "The appliance should be installed and serviced by a ‘Gas Safe’ registered engineer in accordance with the installation instructions and with the rules in force"

Manual available here:

http://www.centralheating.co.uk/system/uploads/attachments/0000/5779/Warmplan_XX_Operating_Instructions_Issue_4.pdf

Acp, August 2017