Parish Church of Cornwood  Devon

St Michael & All Angels

South Elevation & Lynch Gate

St Michael & All Angels the Parish Church of Cornwood is located on the southern border of the Dartmoor National Park, and dates from the 14th Century. A building restoration was carried out during the 1870's Victorian period, and was reopened in 1882. It must be assumed that the Perkins HPHW pressurised heating system was installed during the restoration period. The name of the firm who installed the system is unknown.

In common with all Perkins systems the pipework layout was a continuous loop which was then arranged as two circuits, one serving the North side, and the other the South side of the church.

Spiral tube heating coils and sinuous heating coils were distributed around the perimeter walls of the Church as can be seen from the plan layout above.

Spiral tube heater fitted on north Wall

Spiral tube heater fitted on south wall

4-tier sinuous coil fitted to the face of pews.
Note the two 'banjo' return bends.

The purpose of this valve fitted to the top of the
spiral heater is unknown. It is most likely to be
a form of venting device to remove the air from
the pipework when being vented.

The lack of knowledge of present day heating firms to understand the basic principles of a Perkins sealed and pressurised heating system is made clear in this installation. Small size air vent cocks have been drilled and tapped into the hydraulic tubing by the firm so that the pipework could be air vented after repairs and alterations were carried out to the pipework to correct a water leak. That these air cocks have had to be fitted in so many places around the pipework shows a disturbing lack of knowledge, and their inability to be able to flush vent a sealed pipework system.

4-tier sinuous coil in south aisle

4-tier sinuous coil in north aisle

The original Perkins heating furnace was sited in a basement room and was solid fuel fired. During the earlier part of the 20th century an oil burner was fitted to a new furnace front plate when the system was converted to oil firing.

In the later part of the 20th century the complete furnace, brickwork and heating coils were removed to provide space for a cast iron sectional boiler to be installed. At this time modifications to the plant room pipework and their extension into the church occured. With this modification the Perkins system was downgraded to a conventional low pressure and temperature heating system with a flow temperature of most likely 80 deg C. It is not known whether at this stage it was a pumped system or remained with the original gravity circulation. Electricity was connected to the church in 1952.

The most recent modification to the Perkins system occurred circa 2004 when a new cast iron oil fired boiler made by Potterton was installed. At this time the system was fitted with a pressurisation unit which sealed and pressurised the heating pipework system, and in addtion a pipeline mounted pump was installed.

It is interesting therefore to note how many modifications or upgrades have been carried out during the past 150 years, to this original Perkins HPHW system installed in Victorian times, with it now operating as a conventional LTHW wet sealed heating system with new boiler plant, in the 21st century.

There is evidence in the Church that it had an even earlier heating system which pre-dated the Perkins system. There are several floor gratings in the aisles indicating the existence of a warm air heating system. This is confirmed and shown by the size of a floor grating (now covered with coconut matting) in the south side entrance aisle.

The length of the floor grating indicates that a warm air stove might still be there in the floor pit chamber under the grating. Access to the stove would have been by steps in the chamber leading down from floor level.

4-tier sinuous coil fitted to back of Pew

JULY 2012