St Michael & All Angels   Parish Church of Ufton Warwickshire

The Parish Church of St Michael & All Angels has probably existed since the 13th century but has undergone many alterations with extensions carried out in later centuries. It is a Grade II* Listed building dated 1967. The Heritage Group was excited to discover in this church a remarkable and most unusual heating system, installed during the Victorian period that was used to warm the Church.

What makes St Michael's Church different and therefore special is this unusual underfloor heating system,
most likely installed during a Victorian restoration. 

The heating system is designed on a similar principle to the Roman period underfloor Hypocaust heating.
This Roman heating system used a furnace fired by solid fuel, which fed the hot flue gases into floor voids.
Vertical ducts connecting with the floor voids were built into the walls that acted as chimneys through which
the flue gases would rise until they exited at roof level to atmosphere.

Built into the floor of the Chancel and Nave aisles of the church are several cast iron floor plates each
approx 400mm square with a central removable section. Each floor plate covers a deep brickwork pit.
The bottom of each pit is full of ash several inches deep. The brickwork forming the sides of each pit
is severely scorched and burnt.



An external search of the church found no basement or undercroft where a furnace could have been sited. This indicated there must be an alternative
location for the furnace. The obvious alternative had to be the various floor pits were used as hot fire pits. The ash found in the pits must be the residue
left by the solid fuel fire. The scorching of the brickwork in each pit is also a positive indication of the very high temperatures reached emitted by the fire.

On the removable section of each floor plate is the inscription. MITCHELL'S PATENT WARMING APPARATUS Mitchell has to be the name of the person who devised this unusual method of warming a Church. Although the wording says PATENT a check through all the British Patents issued from 1770 until 1870 shows no mention of a suitable Patent awarded in the name of Mitchell.

  It could be assumed that 'Mitchell's Patent Warming Apparatus' was some form of
  wire cage similar to a brazier which contained the solid fuel fire.

This cage/brazier full of hot coal or coke would have been lowered into the open
pit and the cast iron floor plate then replaced with the centre section left open.
This allowed fresh air to enter the pit chamber to create sufficient draught and
induce the flue gases to enter the floor ducts and travel towards the chimney.  




The passage of the very hot flue gases from each hot pit furnace into and then through the
brickwork ducts would then transfer its heat into the floor slabs and tiles which could then
radiate heat by conduction and radiation into the occupied space of the Church.
 


The duct openings from the sides of the deep pits can be seen in these two images.





A brickwork chimney built in one corner of the Tower was the exit route for the flue gases to
atmosphere from each underfloor duct connecting to its own 'fire pit' furnace. The great height
of the chimney terminating within the upper Tower would have been necessary to create the
draught effect powerful enough to induce and draw the hot flue gases through the underfloor
ducts from the 'fire pits'.

A hinged cast iron flue clean out door is fitted at floor level, through which the chimney would have
been periodically swept and cleaned.The black scorching colour at the base of the internal chimney
indicates that a fire would have been lit there to start and increase the updraught effect needed to
induce and draw the flue gases from the various fire pits.  

Scorching can be seen at the base of the chimney Hinged cast iron access and clean out door

The discovery of a date for the construction of the floor ducts and pits would
be helpful in determining whether any written Church records could still exist.
Whether this method of warming the Church proved successful is doubtful,
but Church records may provide answers to these queries.