[b] :?: Iwish to install a solar hot water system but cannot easily accomodate a std hot water cylinder. Is it possible to purchase tall small dia cylinders; e.g a 120 litre capacity of 400 mm dia ?[/b]
Unles you use a large capacity unvented twin cylinder you are wasting your time. Profesionaly put together systems have a pay back period of around 20 years (unless there is a fairly large swimming pool to be heated then it's about 5 or 6 years). A Heath Robinson system has a pay back period of ..... well never. If you are doing it to save the planet rather than saving money..... well don't. The energy used to mine the metal, mill the metal, manufacture the cylinders, manufacture & transport all the other materials will well exceed any carbon saving you will make. So my advice is unless you can use a 300 litre or more twin coil unvented cylinder, wiyh vaccumm tube collectors with a professionaly put togeather system by the likes of Viessmann or Vailant you are probably going to do more harm than good.