GM572

Abercanaid haystack boiler  

19/12/2003  

Designated  

Merthyr Tydfil  

Troed-y-Rhiw  

305613  

203785  

Industrial  

Haystack Boiler  

Post Medieval/Modern  

The following provides a general description of the Scheduled Ancient Monument. The monument comprises the remains of an iron haystack boiler, set into the retaining wall and bank on the north-east side of the Glamorganshire Canal and directly opposite the house. The haystack boiler was the earliest form of boiler design for use with steam engines and was little more than a giant cylindrical domed kettle (being based on the brewer's copper), designed for use within a heat-retaining brick flue and setting. Thomas Newcomen used the haystack boiler in 1712 and, although they had a very low internal pressure and were gradually superceded by new boiler types, they continued in use into the mid-19th century. The Abercanaid boiler is believed to have been used at the Gethin Pit and brought down to Abercanaid in the 1930s, where it was used as an air raid shelter during the Second World War. It is constructed from wrought iron plates with overlapping riveted seams and measures about 2.5m in diameter by about 3m in height. It now has a panel missing on its north-east side to provide access. This doorway has a tarpaulin cover, held by a wooden frame. The boiler is fronted by a concrete plinth that is about 0.3m in height, with a recessed step under the doorway. The great majority of the boiler is set within the retaining wall and bank; its dome protrudes from the grass topping this bank and the hole upon its summit (where the steam pipe would have originally extruded) now boasts a concrete cap. The brick setting for another haystack boiler was excavated in 1976-9 and is scheduled at Scott's Pit, Swansea (GM336). The monument is of national importance as an exceptionally rare and well-preserved example of this early component of steam engine technology; and for its potential to enhance and illustrate our knowledge of similar industrial features and the contexts within which they were set. The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.