ABB fan drives prevent condensation in Roman bath
Roman Baths suffer the same problem as modern bathrooms — they steam up. To overcome this problem, the Roman Baths in Bath, built in 60 to 70 AD around a natural geo-thermal spring, use ABB drives to control fans to ensure that condensation does not obscure the view of visitors coming to see how Roman engineers used this natural resource to provide bathing facilities for the temple and spa complex that flourished 2000 years ago.
Its present owners, Bath & North East Somerset Council, has recently re-displayed the entire site. One improvement is a walkway 4 m long and 1 m wide so people can walk across the main drain that carries overflow water from the baths to the River Avon. The problem was condensation from warm water obscuring views of the drain.
To address the problem, ABB Drives Alliance member APDS trialled using a 370 W ABB machinery drive controlling a fan. The drive’s clock ran the fan at full speed (50 Hz) overnight using cheap-rate electricity and at 33 Hz during opening hours to keep condensation away and reduce fan noise to an acceptable level. After a successful 6-month trial, two more fans were installed.
Iain Johnston, facilities manager for Heritage Services, a council department, explains, ‘The water comes from the natural hot spring at around 46°C and at this point in the drain has cooled to around 36 to 38°C. When the walkway was installed, we noticed that people could not see the water flowing below through the drain because of condensation.
‘Possible solutions suggested were adding vents alongside the glass, but it was thought that this would make the walkway too hot and steamy. Another was adding heating elements in the glass, but this could weaken the glass and make it unsafe for visitors.’
