Energy Audit for St Mary Redcliffe Church, Bristol

4.4. Controls and Frost Protection
The heating controls to the church are whole inadequate. They currently consist of a time clock
which is not in use and a range of on and off switches. The electric immersion heater to the hot
water tank is currently switched on so that both gas and more expensive electricity is being used to
heat the hot water.
There is also a three port valve controlled by an actuator which switches the output of the boiler
between the heating and/or hot water. This actuator switch is broken and needs to be replaced to
allow for effective control
As there is no operating time clock the heating is currently turned on manually in Mid-October and
turned off in March. During the winter the heating therefore runs constantly 24 hours a day, 7 days a
week. There is some thermostatic control with the use of a Drayton SCR Digistat located in the north
side of the choir stalls but it is not clear how this is connected back to modulate the boiler firing.
It is strongly recommended that the control panel is replaced with a modern control unit such as a
DC1100 controller which includes weather optimisation and has time clocks for heating and
separately for hot water. This has an optimiser so will automatically bring on the heating to bring the
building up to temperature by the time set within the programmer. There is also frost protection
settings on external air temperatures, internal space temperatures and the temperature of the
water in the heating pipes so that minimum levels of heating can be maintained for purposes such as
the organ.
The hot water is currently running constantly as well as having the electric immersion turned on. As
the primary use of hot water is for the café and WC’s it is recommended that the hot water is
provided for the times when the café is open. Outside of these time the hot water tank will continue
to store hot water until it is used up therefore there will still be hot water available in the toilets
after the 3pm café closing time. In order to maintain levels of hot water on a Sunday and Monday is
it recommend that the hot water comes on for two hours in the morning to heat up the tank.
All recommended timings are shown in the table below
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