Gleaming pipes and large boilers share this colourful space with delicate old wood stoves, blackened iron bread ovens and century-old utensils for cooking and lighting fires from Tanzania to Borneo.
"We're a small, humble museum and there are serious inhibitions to coming here, especially for women who think it will be very technical. But we can convince them otherwise," the museum's cheerful director Reinhard Indrak told AFP.
Brennpunkt, German for "burning point", emerged from Vienna's switch to district heating when the city found itself with a mass of old coal and oil heaters on its hands and decided to preserve this part of its history.
And this is how many other small museums saw the light of day, from the Coffee Museum -- filled with all manner of coffee grinders and espresso machines -- to the Circus and Clown Museum and the Chimneysweep Museum, naturally packed with an array of round brushes.
All began as private collections until their owners, or an association or business group, decided to share them with the public.
Entry costs a few euros, opening hours are limited and the exhibits often fill just a room or two, but thousands still go through their doors every year, especially on Museum Night (Lange Nacht der Museen), which Vienna will hold Saturday for the 13th time.
The event, which is also held in other major cities around the world on different dates, lets visitors explore countless exhibits in one evening, from 6 pm to 1 am, with a single ticket.
-- Coffin trials and millennia-old condoms --
A visit to the dentist is not something people usually look forward to, but last year's event attracted some 900 visitors to the Dentistry Museum.
Dentist's chairs dating back to the early 1800s, from uncomfortable-looking wooden seats to plush velvet-covered thrones, trace the profession's history along with early ivory prostheses, gruesome wax moulds of diseased gums once used as teaching aids, and instruments that would not look out of place in a torture chamber.
Unable to draw the same large crowds as the prestigious Art History Museum, the Albertina or even the Planetarium, small collections often rely on school visits.
This is the case of the Contraception and Abortion Museum, a privately run exhibit opened in 2007 by a doctor who felt there was too little awareness of the subject.
The only museum of the sort in the world, it welcomes many classes, especially students aged 13-18 who are happy to get honest information from someone other than their teacher, the museum says.
In the process, visitors also learn that frogs were once used as pregnancy tests and that King Minos of Crete used a fish bladder as a condom as far back as 1200 BC.
For those who prefer art on a smaller scale, the Look Magnet Museum offers a whirlwind tour of the world's greatest art collections ... in the form of refrigerator magnets, displayed in a miniature museum covering just nine square metres (around 100 square feet).
Unlike other exhibits, this one is open just one month every year around Lange Nacht time, and its creator is just 15 years old.
The exhibit, which people peer into from above rather than walking around in, boasts famous works by Picasso, Monet and Giacometti, and is once again expecting some 700 visitors on Saturday.
This year, some 680 museums all over Austria will take part in Museum Night, including 125 in the capital.
One exception will be the popular Funeral Museum, a collection of 19th-century funeral clothes, unusual coffins -- including a re-usable one with a hinged bottom -- and a unique alarm system that was supposed to alert the undertaker if someone had been buried alive.
In past years, people were invited to try out a coffin for themselves -- which they did with delight, says the museum's lively curator, Wittigo Keller.
The surprisingly un-stuffy exhibit -- "it's groovy, with a touch of voyeurism and an unusual topic," says Keller -- will not feature in this year's Lange Nacht for logistical reasons.
Vienna's curious little museums have no shortage of fans, as Andreas Engert, a tourist from Wuerzburg, Germany, testified.
"We've already done all the standard tours," he said drily, as he and a friend examined a 19th-century hearse.