Hi -we have just fitted a horizontal radiator in a kitchen extension 1600x354 (double) gloss black, looks very nice but its not getting very warm its meant to have an output of 5600 btu but it`s nothing like that.It gets warm at the top but luke warm at the bottom.there isn`t an air lockand we`ve taken it off turned it round but still no joy- we have fit a vertical one similar design and that is fine- i was wondering if anybody had fitted these fancy hoizontal ones? any advise greatfully received