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
used as 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 and 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 must be assumed that 'Mitchell's Patent Warming Apparatus' was some form of
a wire cage like 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 furnace through the
brickwork ducts would then transfer its heat
into the floor slabs and tiles
which would 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.

 

JUNE  2013