The firm alerted the police to the scam after it discovered an order to deliver £7,000-worth of wall-hung boilers to the Plumbase branch in St Helens, Merseyside, was fraudulent. Plumbase said it had not placed the order.
A Viessmann spokesman said: “Hopefully this will act as a bit of a warning to other manufacturers.
“Fortunately, one of the sales staff had a query on the order and called Plumbase and found out it hadn’t ordered anything.
“The people who made the order had asked for the local transport company to pick up the order and deliver the boilers to the branch in St Helens.
“They said that the order needed to be unloaded immediately into another van which would be waiting outside the site as they had to go and deliver it straight away.”
The spokesman said the order appeared perfectly normal: “Nobody would have known it was a fake until they were trying to collect payment.”
The police have been unable to track down anyone connected to the incident and the mobile phone listed on the original order could not be traced as it was unregistered.
Viessmann added it was now undertaking extra checks on any orders which seem suspicious and recommended other companies follow suit.
The spokesman said: “We are now keeping an eye out for anything special and checking if delivery instructions are unusual in any way.
“It didn’t work this time, but there is no reason why they will not try to do this again – especially as we are entering the ‘heating season’.”