The Heritage Group were pleased and fortunate to have found and visited a building which still has its original steam engine in use today providing the motive power to drive the ventilation equipment. The steam engine has been in continuous use since 1907 when the building was first opened.

Municipal Technical Institute
College Square East
Belfast - Northern Ireland

The building of the Technical College in College Square caused substantial heart-burnings. Its deplorable siting was the outcome of the financial embarrassment of the Governors of the Royal Belfast Institution. They had long been in debt; and in 1899 resolved on the extreme measure of realizing the site value of the parts of the grounds surrounding the school. The resulting building masks Sloane’s façade of the school, overshadows it, and generally presents an outstanding example of egregious town planning. (1)

1.  “Buildings in Belfast” 1700 – 1914  by C.E.B. Brett  “The Edwardian City” Page 71

Building  programme 1899 to 1907 - Architect Samuel Stevenson.     

The Building Services Engineering Contractor for the project was Musgrave & Co. of Belfast who manufactured and installed the majority of the  H & V equipment.

Their tender dated August 1905 was accepted in the sum of £2880


The building is heated by a warm air plenum system complete with an air washer which for that time period was unusual as it provided a course amount of air conditioning to the ventilation by cooling and /or humidifying the supply air.



Tower Block Plant Area

showing the -

Steam engine

Supply fans

Heater battery

Spray air washer

Drive Shafts

Return / Fresh Air Paths


The steam engine is a Musgrave & Co. of Belfast 15 hp. (operating at 100 psi ) single cylinder horizontal pedestal mounted machine, which drives the two large centrifugal fan impellers through a single direct drive shaft fitted with a friction clutch. On the drive shaft is a 1.5 metre approx. diameter flywheel with an adjacent 1.5 metre diameter freewheel flywheel also fitted on the drive shaft.  The freewheel flywheel was originally belt driven by a DC motor (now removed) which was engaged to the drive shaft through a screw clutch.  This motor provided a standby facility to drive the shaft powering the ventilation fans when the steam engine was being repaired or required maintenance.






The steam supply was originally generated from a Lancashire pattern boiler, which has now been replaced by a packaged unit. The original boiler plant was coupled to both a superheater and flue side economiser. The steam boiler supplies the engine, air heater battery, heating and domestic HWS calorifiers.
Exhaust steam from the engine is first fed through a feed water pre-heater before being discharged to waste as condensate.  The pre-heated feed water is then fed into the boiler hotwell.  No waste steam from the engine is recovered as condensate, due to the possibility of oil contamination, which would create problems within the steam boiler plant.


Sited in the  tower is the return / fresh air is the mixing chamber at first and second floor levels are two spinning disk spray humidifiers / washers which produced a small amount of cooling in the summer and humidification during the winter. Each unit is about 2.4 metres in diameter. The spinning disks were driven by belts and pulleys from the main steam engine drive shaft.
The water supply to the two spinning disks was designed to provide for re-circulation. All surplus spray water was collected in a gulley at the bottom of each disk unit which then drained back through a pipe to a basement collecting tank.  A steam operated Worthington Pump unit then returned the water back up to re-supply the sprays. 
This air washing equipment although still in position is no longer in use.

Front view of spinning Disk Humidifier / Washer

Original Worthington steam driven Water Pump


Two 5 metre approx. diameter centrifugal fans connected in parallel as supplied by Musgrave & Co of Belfast from their “Ulster” range provide the supply air to the building.  The ventilation plant also comprises on the fan suction side in the direction of air flow a ‘V’ pattern filter bank and a steam fed gilled tube air heater battery, which has 6 separate sections (3 wide x 2 high).
The supply air from these fans is discharged into large walkway sized brickwork ducts which are constructed under the Ground Floor corridors. From these walkway ducts smaller riser ducts are connected to supply air to the individual rooms at all floor levels of the building. Each riser duct is contained within the fabric of the building structure. All branch supply duct take off connections within the basement ducts are fitted with a hot water re-heat booster battery and volume control damper (VCD).  Each VCD has a canvas blind shutter which can be raised or lowered to suit its correct regulating control position. The blind can then be screw locked into that position.
Each main classroom and other areas in the building have a supply air register fitted at high level.  A similar air register at low level provides the extracted air path into the corridor.  A percentage of this extracted air is used for re-circulation and is routed through the main corridors at each floor level which act as the pathway for the air to return to the tower chamber where it mixes with the incoming fresh air in the tower before returning to the air handling plant. The remaining percentage of vitiated air is extracted at fourth floor level through ceiling mounted extract gratings into an above ceiling main duct before exiting to atmosphere through four roof mounted turrets.


Centrifugal Ventilation Fans

Plenum Walkway Duct

Re-heat Booster Batteries

Room Air Transfer Grilles

Corridor Return / Recirculation Path

Roof Extract Turretts

The two Musgrave's of Belfast Centrifugal fans with paddle
  blade impellors which are shaft driven from the steam engine

Main direct shaft drive from the steam engine

View of paddle blade impellors

Views along the plenum walkway ducts

Typical return air path through corridor

Room Air Transfer Grating

Booster heater with blind in closed position

Blind in open position

Each different size of supply and extract grating
manufactured by Musgrave & Co. had the letters
MTIB and the year 1906 woven into the design
pattern of the wrought iron gratings.

Roof extract turret


The boiler plant supplies two steam/water vertical pattern calorifiers.  These provide hot water to serve all the ventilation basement duct re-heater batteries and remaining heating equipment. 
The original calorifiers were manufactured by Royles,Ltd of Irlam Manchester. The battery of each steam chest had a tube bundle which was of the “pinched tube” pattern.   Both these calorifiers have now been replaced and updated.
All the flow and return pipework connections to the re-heat booster batteries in the basement walkway ducts are fitted with gate valves for isolation and possible regulation. These batteries are all fed from a single pipe circuit but to maximise water circulation through each battery, tongue tees are fitted to both the flow and return branch pipe connections of each heater.

Pinched battery tubes from original calorifiers

Gate valve controlling sub-circuit

Piston pattern expansion joint

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MAY 2002