the back gets filled with insulation and covered with plastic. everything is glued together with tec7. the insulation is what's left over after insulating the water tank and is there to prevent the heat collected at the front to be radiated out at the back. the material used at the back has to be very heat resistant since the collectors can get very hot (temperatures in the absorber can get up to well over 100°c!)
the holes where the copper tube comes out of the collector are also sealed with tec7. i used a PU based black paint to seal all the edges of the board and all the screw holes.
it all looks a bit scruffy done ;-) but let function prevail over form and i'm pretty confident it can take at least 25 belgian winters!
the front needs some glazing. just like in a greenhouse you want to trap the heat inside. the material normally used for this kind of application is either (hardened) glass or double layer polycarbonate.
however i stumbled across this PVC material that is very thin - only one mm - very easy to work with - it can be cut with a pair of scissors - and, unlike traditional PVC, can take high temperatures and is UV resistant. it also came cheap.
the use of this material is experimental though. when it lasts 10 years i'll be happy. when it fails - when ever that is - i'll replace it with something more traditional.
i decided it's not necessary to make the window removable so i just glued it on to the top. when it has to be removed it can simply be cut off. this is the easiest and cheapest way of mounting the glazing.
the absorber for the first time out in the sun (it's on it's side here). before installing it on the wall i leave the absorber in the garden for a while to check how it holds out in sun and rain.
Geen opmerkingen:
Een reactie posten