Christ Church Unitarian Chapel is the oldest non-conformist Chapel in Bridgwater there being a building on this site since 1662. This first meeting house was demolished in 1683 and its contents destroyed.
The meeting house as presently built was erected in 1688 with an extensive restoration carried out in 1788.
The engineering services comprising gas lighting and central heating were installed during the Victorian period.
The building was Listed Grade II* in 1950.
The Heritage Group was notified that the heating system in this Chapel was thought to have a saddle type wrot iron boiler still in situ. As saddle boilers can date back to the early Victorian era every one now discovered has historic and engineering heritage importance.
A site visit March 2013 by the Heritage Group was arranged for an inspection of the Chapel and its heating system. This wet system had remained unchanged since its installation in the mid-Victorian period circa.1860 and was thought to have a most unusual water circulation system. What was found became an exciting discovery.
Chapel has four aisles forming a rectangle around the
building that allows access to the box pews on either
side. In the centre of the floor of each aisle are laid
decorative cast iron floor plates with small openings
along either edge. The floor plates are laid in sections
each approx 400mm wide by 1500 mm length.
boiler for the heating system sited in a small
semi-basement room is a saddle pattern set into
brickwork, with flow and return cast iron (CI) pipework
laid within the brickwork enclosing the boiler.
There was no name inscribed on the boiler, but the decorative floor plates in the aisles of the Chapel bore the name Garton & King Manuft’s Exeter. This engineering firm was well known in south west England and had been in existence since the 17th century with their own ironfoundry operating since the 19th century.
flow and return CI pipework (approx 3” dia.) from the
boiler then entered into a small under floor duct. What
then made this heating system different and possibly
unique was that these two pipes appeared to connect
directly to a metal trough.
of the floor plates showed that there was a cast iron
metal trough sited underneath. The trough was fitted
tight to the underside of the floor covers and secured
to it by screws. Each length of trough was constructed
with one end socket into which the spigot of the next
section was jointed by using caulking hemp/rope soaked
in black mastic. Both sides of the trough had flanged
tops with a slight grove into which was laid a hemp rope
soaked in black mastic. This sealed the top of the
trough when screwed to the underside of the plate making
the trough watertight.
metal trough (internal dimensions of 81/2 ins wide by 5
ins deep) would have been filled with water that
circulated by gravity circulation. The heating system
water circuit was arranged as a simple single loop
around the four aisles from and returning back to the
The floor surface of the four aisles is flat and level with no steps, so the water could only have circulated due to the circulating pressure created by the small height difference of approx 900 mm between the flow and return pipes connecting to the saddle boiler.
strange feature of this heating installation is that no
obvious cold feed or air vent pipework could be found.
However upon inspection, the two far corners of the
floor trough are each fitted with a small lead pipe
having an open end, placed into the top of the trough.
These lead pipes then rise up inside the end corner of
the adjacent box Pew, which has a series of small holes
drilled into the box pew corner. This appears to be the
means by which the sealed water trough was air vented.
query was deciding what method could have been used for
filling the water trough. Inspection of the decorative
floor plates found a number of small circular
holes drilled in the centre of the
plate that could have been used as filling positions.
The holes are located in one aisle at the start of the
trough on the flow side, with similar openings at the
end of the trough on the return. These circular holes
could have held a funnel through which the water was
poured. Dip-sticks would have been used to measure the
correct depth of water. Removable plugs could then be
fitted in the holes.
did the water come from that was needed to originally
fill the system. In the semi-basement room close to the
boiler is an open Well full of water. This Well must
have provided the water used to fill the whole system,
most probably by bucket. The quantity of water
calculated to fill the trough would have taken approx
100 normal size buckets.
To have had any positive effect in raising the space temperature of the Chapel would have required the circulating water to have been very hot to maximize the radiant and convective output. The high surface temperature of the floor plates may have been capable of causing a skin burn if touched.
The saddle boiler was solid fuel fired with no safety or temperature controls fitted, so the overall control of boiler temperature and its output was at the discretion of the person acting as the stoker fireman. To start the water contents of the system moving and achieve an initial gravity circulation must have required the boiler flow temperature to be very high close to boiling point. Otherwise there would not have been sufficient temperature difference between flow and return pipes to “kick start’ the circulation.
Whether this new method of circulating hot water was capable of providing sufficient heat to raise the air temperature in the Chapel to an acceptable comfort level is questionable. The water circulating in the trough could only transfer its heat to the occupied space above firstly, by conduction and radiation from the warm surface of the floor plates, and secondly by convection through the small openings in the sides of each section of floor plate.
As the building would have had intermittent usage, the length of pre-heat time would have been disproportionate to achieve the required space temperature. Most likely the boiler when started at the commencement of the heating season would have remained alight and only banked down during the period when the Chapel was not in use. This method would have kept the large quantity of water in the trough always warm never allowing it to become cold.
The success of this method of circulating hot water around the building is highly debatable. So the search must continue to discover other Garton & King heating systems from the Victorian period having a similar water circulatory system. Until another system is found then the assumption must be that this new method was most likely a one-off that proved to be unsuccessful.