Flushing out heater matrix

[lolsteve]

So think my heater matrix is a bit blocked up from when I ran a bit of rad weld as the fans aren't blowing all that hot until I've been driving the car some time. Perhaps only allowing a small amount of hot coolant through which when it isn't that hot isn't making much of an impact?

Been looking into blowing water backwards through the pipes going through the bulk head as now im at my parents i have access to a hose pipe. But just wondering if people have tried the radflush products etc and if that would do any good? 
http://reviews.halfords.com/4028/777607/reviews.htm