BOTANIC  GARDENS.   BELFAST


 

Heating System discovery in the Tropical Ravine House.

The existing  heating system is provided by banks of  4-inch cast iron pipework coils which are routed at high and low level around
 the glazed perimeter of the building.
During investigative works carried out recently to discover the source of leak/s which were
 causing the constant loss of water from the system it was found that  another circuit of pipework had been run inside a
 perimeter brickwork duct which had been purposely covered with soil.
 

When an entry into this duct was opened up it was found to start at a height as high as a walkway but then gradually decreased in height until it became a crawlway before it finally ended as two adjacent earthenware hollow pot  air passageways. At this point the cast iron pipework left the duct and was then buried in the ground. Through the passage of time the wet soil had corroded the surface of the cast iron and ultimately the pipe wall eventually failed and this created  the leaks. 

However, the discovery of this duct brought to light an earlier method of heating the Tropical Ravine House. The duct had originally been used as a horizontal path for the flue gases to escape from an open hearth fire which was kept constantly fired in a basement room.  The flue gases supposedly warmed the walls of the brickwork duct and the soil piled around the duct. This provided a continuous constant heat flow into the Ravine House. The duct originally had been used as a horizontal path for the flue gases to escape from an open hearth fire which was  constantly kept fired in a basement room. 


The gradual reduction in size and area of the flueway kept the flue gases moving at a slow enough velocity, so that they could distribute and transfer their heat into the surrounding brickwork structure. At the end of the duct the flue gases finally passed into the two earthenware pot shafts before connecting into a vertical brick chimney at the other side of the building from the fire room.

It must have soon been found that this method of heating was proving unsuccessful as the long horizontal duct run for the flue gases could not provide sufficient draught in the system to draw the gases into the chimney.

We can only imagine what the room conditions were like for the unlucky stoker trying to maintain the fire well alight.

That this original system did not prove  successful  is evident by its replacement with  the more reliable method of using 4" cast iron hot water coils as the heating system.



The Palm House.    Belfast



An interesting and noticeable feature within  the Dome Area of  The Palm House can be
found in the shaped cast iron sectional floor gratings which formed part of the heating
system manufactured and installed  by Musgrave & Co Ltd.  of Belfast.

 
When Musgrave came to fix the floor gratings which were to follow the elliptical route of the pathway, it was found that they had been cast slightly too large. Due supposedly to wrong measurements being taken. The sections were out of alignment and would not fit together following the route of the pathway. Consideration was then given to scrapping all the cast iron sections, but an alternative and unusual solution was adopted to correct the misalignment.
To overcome these  slight errors in the measurements of the gratings, the floor levels of the pathways were laid to create a slight camber in either direction, outwards or inwards to compensate  and correct for these dimensional errors. 
Also where found  necessary slight offsets had to be formed in the alignment of the ducts under the pathway.


 
 The Heat Wall 


The back wall of the Palm House was constructed as a double skin cavity brick wall plastered on either side.

This allowed the wall to be used as a 'hot wall', and up through the cavity passed the flue gases from a fire in a brickwork furnace  sited in a basement room.

The outer skin of the wall tapers inwards towards the top of the Palm House which narrowed the pathway for the flue gases and slowed them down to maximise the heat transfer into the brickwork walls. 

At the top of the wall along the roof ridgeline a few decorative flue terminals were fitted to allow the flue gases to escape to atmosphere. 

Stokers were employed who worked in shifts day and night to keep the fires permanently alight. They lived on the premises in the rooms at the rear of The Palm House.

This early method of heating the glass houses was not successful so in 1862 a wet heating system was installed by Musgrave and C0mpany for 95 using banks of 4" cast iron piping fitted under the plant stagings, fed from a Cockey's patent boiler. New boilers were installed in 1871 and they were supplemented in 1881 by large terminal end saddle boilers.  The installation work was carried out by Wimmington and Co. who also removed the pipes of the smoke flues. Later changes were made 1892 to the heating  when the Saddle boiler was taken out and the firm of John Hall, Queen Street installed two Hartley and Sugden boilers. 

 

CIBSE  HERITAGE GROUP
DECEMBER 2001