C/H addatives/concentrate
 

I have a wood burning stove with back boiler. Its quite difficult to
access the loft/feeder tank, so I would like to use the Screwfix
Concentrate(No nonences) additive. This comes in a sealant like tube,
with a small kit. is it just a case of attaching this to the stopcock
on the bottom of the boiler, opening and filling. Does the water go
everywhere? How much to use? does it block drain for future?. ANY help
advice/tips would be appreciated.?
Thanks