The brand utilised out of home (OOH) advertising to encourage members of the public to visit its green and white machine, which was complete with the #keepsmiling hashtag.
Those who approached the machine were invited to stand on a white circle on the floor and smile, at which point they received a complimentary warm beverage, such as a coffee or hot chocolate.
The smile station was accompanied by a snug designed to protect commuters from the winter chill, and brand representatives were on hand to provide free warmth kits.
The acitivity kicked off in Birmingham on Blue Monday (18 January), and also visited Manchester Piccadilly (20 January) and Glasgow (22 January).
Those who couldn't make it down to the machines were invited to take part online, via a smile activated Facebook app. The app provided a warmth rating, which was used to identify the warmest location in the UK.
Vaillant's annual Warmth Week encourages people to remain cheerful during the cooler months by reconnecting with their homes.
Brands such as and utilised smile activated vending machines last year.
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