You can buy a range of difference radiator reflectors in DIY stores. The basic idea is that they reflect heat away from the wall behind the radiator and hence keep the warmth in the room. This all sounds great, however, like with many things in life there are some additional pieces of information required in order to get it right.
The panels can and do reflect heat, however the best course of action is to get the warm air circulating from behind the radiator and into the room. The panels that have a serrated profile do this, whereas the sheet / roll type do not. So if you are buying a reflect why not get one that does both jobs well.
The second point is where to put them. Putting them behind radiators that are housed on internal walls does not really help as they only allow the room to heat up quicker and hence cool down quicker. If the radiator was left ‘untreated’ then the wall behind acts as a thermal store and absorbs some of the heat when the heating is on and then releases it again when it goes off. So the only real area where these reflectors earn their money in on uninsulated external walls. So if you have a solid walled property that is not insulated or an unfilled cavity wall then it will be a wise investment to use these panels here.
The profiled reflectors are available on line from companies like HeatKeeper. Their panels do not require radiators to be removed and so the process of fitting is very simple.