Sair,
trust me its an old ionics system, there early systems were infact mild steel with a blue powdercoat finish, and the ro was tcalled a nimbus or rombus which came on a s/steal frame bolted to there frame.
they then moved onto stainless steel box section there first heater was run by a gas cylinder with the exhaust port out of the top the vans they sold were renault masters, this is one of theres.
the ro system is now sold as a stactic by tucker uk, ionics or over the top as they were called brought over the first poles (tucker poles)
i know this because i had a demo back in '99 and my old boss brought a system in 97-98 one of the first they did.
regards, stuart