[0001] The present invention relates to methods and apparatus for inhibiting bacteria growth
in a water supply and monitoring compliance in such methods and apparatus. In particular,
but not exclusively, the present invention relates to methods and apparatus for inhibiting
Legionella growth in a water supply.
[0002] All water systems can potentially cause hazard to health through the system becoming
colonised and then the subsequent growth of water borne bacteria. The most common
of these is Legionella. In the UK, under the Health and Safety At Work Act and the
Control of Substances Hazardous to Health Regulations, employers and landlords have
responsibility for risk assessing their water system and then putting measures in
place to prevent and control the proliferation of bacteria. In the UK, the Health
and Safety Executive (HSE) has produced the Approved Code of Practice L8 (ACoPL8)
and corresponding technical guidance (HSG274 part 2).
[0003] Legionella requires a food source to feed on and grow. Therefore, all water systems
should be routinely cleaned and inspected. The bacteria can only grow if the water
that it is living in is stagnant and not moving. So, if the water regularly flows
then the bacteria do not have a chance to grow. In water below 20 degrees C, the bacteria
become dormant. Above 45 degrees C, the bacteria start to die and, from 72 degrees
C, the bacteria die instantly. Consequently, one of the measures that is used to control
and prevent the proliferation of Legionella is to ensure that the hot water in a hot
water system of a building is, for at least some of the time, at a sufficiently high
temperature to kill bacteria.
[0004] Therefore, a common approach for inhibiting bacteria growth is to ensure the hot
water delivered to the outlet taps has a temperature of at least 50 degrees C within
60 seconds of opening the tap. Conventionally, this is performed manually and it is
necessary for operatives to visit each test site, draw water from each outlet and
record the temperature of the water after 60 seconds. Typically, this is done monthly.
[0005] Another approach that is recommended is for the stored water temperature (which is
usually recommended to be stored at at least 60 degree C) to be regularly raised to
72 degrees C. The water is then circulated round the system and each outlet opened
one at a time and the water drawn through each outlet for 60 seconds until all outlets
have been opened. This is known as a pasteurisation cycle and it should be performed
if a hot water system has been non-operational for a prolonged period. This should
also be done annually. However, this process is potentially hazardous as there is
a risk of scalding to users of the outlets in the building.
[0006] According to a first aspect of the present invention there is provided an apparatus
for monitoring the temperature of water in a hot water system of a building, the apparatus
comprising:
flow means adapted to selectively prevent or allow hot water to flow from the hot
water system to a drain;
a temperature sensor adapted to measure the temperature of water flowing to the drain;
and
a controller connected to the flow means and connected to the temperature sensor for
receiving measurement data of the temperature of water flowing to the drain.
[0007] Optionally, the apparatus includes communication means for communicating the measurement
data to a remote location. The remote location may be a control station.
[0008] Alternatively or in addition, the apparatus may include a memory for storing the
measurement data.
[0009] Optionally, the communication means comprises a transmitter device for wirelessly
transmitting the measurement data to the remote location.
[0010] Optionally, the controller is adapted to receive control instructions from a remote
location via the communication means.
[0011] Optionally, the communication means comprises a receiver device for wirelessly receiving
the control instructions.
[0012] Optionally, the communication means comprises a transceiver device.
[0013] According to a first embodiment of the invention, the apparatus may include a sampling
conduit having an inlet which is connectable to the hot water system and an outlet
which is connectable to the drain.
[0014] The flow means may comprise a valve provided along the conduit for selectively allowing
or preventing the flow of hot water within the conduit to the drain.
[0015] Optionally, the controller is coupled to the valve for selectively opening the valve.
Optionally, the controller is connected to a motor adapted to operate the valve.
[0016] Optionally, the controller is adapted to open the valve in response to an open valve
control instruction being received.
[0017] Optionally, the controller is adapted to close the valve in response to a close valve
control instruction being received.
[0018] Alternatively or in addition, the controller may include a timer and the controller
may be adapted to open the valve at one or more pre-set times. Alternatively or in
addition, the controller may be adapted to close the valve at one or more pre-set
times or after the expiry of a pre-set time interval from when the valve was opened.
[0019] According to a second embodiment of the invention, the apparatus may be mountable
to an existing tap of the hot water system.
[0020] Optionally, the apparatus includes a motor for operating the tap.
[0021] The apparatus may include clutch means such that the user may manually operate the
tap. Alternatively or in addition, the apparatus may include a user control switch
which causes the motor to turn the tap.
[0022] Optionally, the temperature sensor is in contact with the tap. Optionally, the temperature
sensor is in contact with the stem of the tap.
[0023] According to a third embodiment of the invention, the apparatus may be adapted to
replace an existing tap of the hot water system.
[0024] The apparatus may include a valve for selectively allowing or preventing the flow
of hot water to the drain. The apparatus may include a motor adapted to operate the
valve. The valve may be operable by the controller or by a user control.
[0025] Optionally, the controller is adapted to open the valve in response to the performing
of a pasteurisation cycle. Optionally, the controller is adapted to sense when a pasteurisation
cycle has been initiated.
[0026] The controller may be adapted to open the valve in response to the measured temperature
being greater or equal to a predetermined value. The predetermined value may be greater
than 60 degrees C. The predetermined value may be around 70 degrees C.
[0027] Alternatively or in addition, the controller may be connected to a boiler control
unit which is adapted to control the boiler for performing a pasteurisation cycle.
Optionally, the command from the boiler control unit to the boiler to perform the
pasteurisation cycle is also received by the controller.
[0028] Optionally, an apparatus is provided at one or more hot water outlets or sentinel
points of the building. Optionally, an apparatus is provided at each hot water outlet
of the building.
[0029] According to a second aspect of the present invention there is provided a method
of monitoring the temperature of water in a hot water system of a building, the method
comprising the steps of:
using a controller, selectively preventing or allowing hot water to flow from the
hot water system to a drain;
using a temperature sensor, measuring the temperature of water flowing to the drain;
and
connecting the controller to the temperature sensor so that the controller can receive
measurement data of the temperature of water flowing to the drain.
[0030] Optionally, the method includes communicating the measurement data to a remote location
using the controller.
[0031] Alternatively or in addition, the method may include storing the measurement data
using the controller.
[0032] Optionally, the controller includes a transmitter device for wirelessly transmitting
the measurement data to the remote location.
[0033] Optionally, the method includes sending control instructions from the remote location
to the controller.
[0034] According to a first embodiment of the invention, the method may include connecting
the inlet of a sampling conduit to the hot water system and connecting an outlet of
the sampling conduit to the drain.
[0035] The method may include locating a valve along the conduit for selectively allowing
or preventing the flow of hot water within the conduit to the drain.
[0036] According to a second embodiment of the invention, the method may include mounting
an apparatus comprising the controller to an existing tap of the hot water system.
The apparatus includes a motor for operating the tap.
[0037] According to a third embodiment of the invention, the method may include replacing
an existing tap of the hot water system with an apparatus comprising the controller.
[0038] The apparatus may include a valve for selectively allowing or preventing the flow
of hot water to the drain. The apparatus may include a motor adapted to operate the
valve. The valve may be operable by the controller or by a user control.
[0039] The method may include opening the valve in response to the performing of a pasteurisation
cycle. Optionally, the controller is adapted to sense when a pasteurisation cycle
has been initiated.
[0040] The invention will be described below, by way of example only, with reference to
the accompanying drawing, in which:
Figure 1 is a schematic view of an apparatus in accordance with a first embodiment
of the invention.
[0041] Figure 1 shows an apparatus 10 for monitoring the temperature of water in a hot water
system of a building.
[0042] The hot water system comprises pipework 100 connected to a boiler 110 and associated
pump 112 for circulating hot water around the building for heating and for supplying
hot water to the taps 102 provided at various sink units 104 in the building. The
apparatus 10 is provided at each sink unit 104.
[0043] The apparatus 10 comprises flow means which is adapted to selectively prevent or
allow hot water to flow from the hot water system to a drain.
[0044] In the embodiment of Figure 1, a sampling conduit 20 has an inlet 22 which is connected
to the pipework 100 leading to the sink 104 via a T piece 106 and an outlet 24 which
is connected to a drainpipe 108 of the sink 104 via a second T piece 106. The flow
means comprises a motorised valve 30 provided along the conduit 20.
[0045] A temperature sensor 40 is provided for measuring the temperature of water flowing
to the drainpipe 108. This is a contact sensor which is in contact with the conduit
20.
[0046] A controller 50 is connected by extra low voltage wiring 52 to the motorised valve
30 and to the temperature sensor 40. The controller 50 receives the sensed temperature
measurement data. The controller 50 includes a transceiver which wirelessly communicates
the measurement data to a remote location (not shown). At this remote location is
a control station for the personnel who are responsible for ensuring compliance that
the hot water system is effectively inhibiting the growth of water-borne bacteria.
[0047] The controller 50 can also receive control instructions from the control station
via the transceiver. The controller 50 can receive an open valve control instruction
and, in response, open the valve 30 to allow water to flow in the conduit 20 to the
drainpipe 108. Similarly, the controller 50 will close the valve 30 in response to
a close valve control instruction being received.
[0048] In use, the control station can send an open valve control instruction to the controller
50 which will then open the valve 30. Hot water will flow in the sampling conduit
20 to the drainpipe 108. The temperature sensor 40 will sense the temperature of the
flowing water. The temperature data is sent to the controller 50 which is then wirelessly
transmitted to the control station.
[0049] This continues for at least 60 seconds, after which it is determined if the temperature
has reached 50 degrees C. If it has then the system is in compliance. If not, remedial
action can be undertaken. After the period of at least 60 seconds, the control station
can sent an instruction to the controller 50 to close the valve 30. Alternatively,
the controller 50 can include a timer and the controller 50 can close the valve 30
after the expiry of a pre-set time interval of at least 60 seconds.
[0050] The apparatus can also be used when remotely performing a pasteurisation cycle. The
boiler 110 can be adapted such that it can be controlled from the control station.
An advantage of remote operation (and utilising the invention) is that it is not necessary
to arrange access to the building for operatives. Therefore, the pasteurisation cycle
can be performed at a time of zero or low occupancy, such as during the night. Consequently,
the risk of a person in the building being scalded when using the tap 102 is zero
or low.
[0051] Also, as this is a time of zero or little water use by users, which could affect
the results of the testing. It should also be noted that the hot water is flowing
from the pipework 100 direct to drain, rather than out of the tap 102 and to the drain
via the sink hole. This further reduces the risk of scalding.
[0052] In use, the control station may send a command to the boiler 110 to raise the water
temperature to 72 degrees C. Once this has been achieved, the water is then circulated
around the system by the pump 112. The control station now sends an instruction to
the controller 50 to open the valve 30.
[0053] Alternatively, the controller 50 can be adapted to sense when a pasteurisation cycle
has been initiated. For example, the controller 50 can be connected to a boiler control
unit adapted to control the boiler 110 for performing a pasteurisation cycle. The
command from the boiler control unit to the boiler 110 to perform the pasteurisation
cycle can then be also received by the controller 50.
[0054] The temperature sensor 40 can be used to confirm that the water is at the correct
temperature. After performing the pasteurisation cycle, the control station can control
the boiler 110 to reduce the water temperature back to normal conditions. The control
station also instructs the controller 50 to close the valve 30.
[0055] According to a second embodiment of the invention, the apparatus 10 can be mountable
to an existing tap 102 of the hot water system. The apparatus can include a motor
for operating the tap 102. Clutch means can be provided so that the user may manually
operate the tap 102. Or there may be a user control switch which causes the motor
to turn the tap 102. In this embodiment, the apparatus 10 can be a self-contained
unit, incorporating the controller 50. However, the valve 30 may be omitted since
the tap 102 provides this function. The temperature sensor 40 may be in contact with
the stem of the tap.
[0056] According to a third embodiment of the invention, the apparatus 10 may replace the
existing tap 102. The apparatus 10 would then include the valve 30 and motor for operating
the valve 30. The valve 30 can be operable by the controller 50 or by a user control.
[0057] Various modifications and improvements can be made to the above without departing
from the scope of the invention.
1. An apparatus for monitoring the temperature of water in a hot water system of a building,
the apparatus comprising:
flow means adapted to selectively prevent or allow hot water to flow from the hot
water system to a drain;
a temperature sensor adapted to measure the temperature of water flowing to the drain;
and
a controller connected to the flow means and connected to the temperature sensor for
receiving measurement data of the temperature of water flowing to the drain.
2. An apparatus as claimed in claim 1, wherein the apparatus includes communication means
for communicating the measurement data to a remote location.
3. An apparatus as claimed in claim 2, wherein the communication means comprises a transmitter
device for wirelessly transmitting the measurement data to the remote location.
4. An apparatus as claimed in claim 2 or 3, wherein the controller is adapted to receive
control instructions from a remote location via the communication means.
5. An apparatus as claimed in claim 4, wherein the communication means comprises a receiver
device for wirelessly receiving the control instructions.
6. An apparatus as claimed in any preceding claim, wherein the apparatus includes a sampling
conduit having an inlet which is connectable to the hot water system and an outlet
which is connectable to the drain.
7. An apparatus as claimed in claim 6, wherein the flow means comprises a valve provided
along the conduit for selectively allowing or preventing the flow of hot water within
the conduit to the drain, and wherein the controller is coupled to the valve for selectively
opening the valve.
8. An apparatus as claimed in any preceding claim, wherein the apparatus is mountable
to an existing tap of the hot water system.
9. An apparatus as claimed in claim 8, wherein the apparatus includes clutch means such
that the user may manually operate the tap.
10. An apparatus as claimed in any preceding claim, wherein the apparatus is adapted to
replace an existing tap of the hot water system.
11. An apparatus as claimed in claim 10, wherein the apparatus includes a valve for selectively
allowing or preventing the flow of hot water to the drain.
12. An apparatus as claimed in any preceding claim, wherein the controller is adapted
to open the flow means in response to the performing of a pasteurisation cycle.
13. An apparatus as claimed in claim 12, wherein the controller is adapted to sense when
a pasteurisation cycle has been initiated.
14. An apparatus as claimed in any preceding claim, wherein an apparatus is provided at
a plurality of hot water outlets of the building.
15. A method of monitoring the temperature of water in a hot water system of a building,
the method comprising the steps of:
using a controller, selectively preventing or allowing hot water to flow from the
hot water system to a drain;
using a temperature sensor, measuring the temperature of water flowing to the drain;
and
connecting the controller to the temperature sensor so that the controller can receive
measurement data of the temperature of water flowing to the drain.