Ancient Monuments

History on the Ground

This site is entirely user-supported. See how you can help.

Abercanaid haystack boiler

A Scheduled Monument in Troed-y-rhiw, Merthyr Tydfil (Merthyr Tudful)

We don't have any photos of this monument yet. Why don't you be the first to send us one?

Upload Photo »

Approximate Location Map
Large Map »

If Google Street View is available, the image is from the best available vantage point looking, if possible, towards the location of the monument. Where it is not available, the satellite view is shown instead.


Latitude: 51.7248 / 51°43'29"N

Longitude: -3.3679 / 3°22'4"W

OS Eastings: 305613

OS Northings: 203785

OS Grid: SO056037

Mapcode National: GBR HP.2FLD

Mapcode Global: VH6CY.KXW4

Entry Name: Abercanaid haystack boiler

Scheduled Date: 19 December 2003

Source: Cadw

Source ID: 4023

Cadw Legacy ID: GM572

Schedule Class: Industrial

Category: Haystack Boiler

Period: Post Medieval/Modern

County: Merthyr Tydfil (Merthyr Tudful)

Community: Troed-y-rhiw

Built-Up Area: Merthyr Tydfil

Traditional County: Glamorgan


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Thomas Newcomen used the haystack boiler in 1712 and, although they had a very low internal pressure and were gradually superceded by new boiler types, they continued in use into the mid-19th century.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.

Source: Cadw

Other nearby scheduled monuments is an independent online resource and is not associated with any government department. All government data published here is used under licence. Please do not contact for any queries related to any individual ancient or schedued monument, planning permission related to scheduled monuments or the scheduling process itself. is a Good Stuff website.