U.S. patent application number 13/147841 was filed with the patent office on 2011-12-01 for controlling under surface heating/cooling.
This patent application is currently assigned to UPONOR INNOVATION AB. Invention is credited to Ulf Jonsson, Andreas Vogel.
Application Number | 20110290470 13/147841 |
Document ID | / |
Family ID | 40404649 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110290470 |
Kind Code |
A1 |
Jonsson; Ulf ; et
al. |
December 1, 2011 |
CONTROLLING UNDER SURFACE HEATING/COOLING
Abstract
The invention relates to controlling an under surface
heating/cooling. During a heating mode, the room temperature is
increased by increasing the flow of the liquid in a supply loop
(3). If the set point has an increase that is greater than a
pre-determined value, the supply temperature of the liquid is
increased. During a cooling mode, the room temperature is decreased
by increasing the flow of the liquid in the supply loop (3).
Correspondingly, in response to a set-point change greater than a
pre-determined value, the supply temperature of the liquid is
temporarily decreased.
Inventors: |
Jonsson; Ulf; (Upplands
Vasby, SE) ; Vogel; Andreas; (Sulfeld, DE) |
Assignee: |
UPONOR INNOVATION AB
Virsbo
SE
|
Family ID: |
40404649 |
Appl. No.: |
13/147841 |
Filed: |
February 16, 2010 |
PCT Filed: |
February 16, 2010 |
PCT NO: |
PCT/IB2010/050686 |
371 Date: |
August 4, 2011 |
Current U.S.
Class: |
165/287 |
Current CPC
Class: |
G05D 23/1934 20130101;
Y02B 30/24 20130101; Y02B 30/762 20130101; F24D 3/12 20130101; Y02B
30/00 20130101; F24D 19/1009 20130101; Y02B 30/70 20130101 |
Class at
Publication: |
165/287 |
International
Class: |
F28F 27/00 20060101
F28F027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2009 |
FI |
20095148 |
Claims
1. A method of controlling an under surface heating in which a room
is heated using a supply loop in which liquid is circulated for
heating the room, the method comprising increasing room temperature
by increasing the flow of the liquid in the supply loop, and in
response to a set-point change greater than a pre-determined value,
increasing temporarily the supply temperature of the liquid.
2. A method according to claim 1, comprising prioritizing by a
controller zones with latest set-point changes for a period of time
or until the set points are reached.
3. A method according to claim 1, comprising supplying cooler
liquid to the loop before reaching the set point for reducing
overshoot.
4. A method according to claim 3, wherein the cooler liquid is
obtained by opening temporarily at least some of the actuators of
other loops.
5. A method according to claim 1, comprising analyzing previous
transitions and outside temperatures and optimizing transition
ramps on the basis of the analysis.
6. A method according to claim 1, comprising controlling the flow
of the liquid on and off such that during a duty cycle the flow is
high and between the duty cycles the flow is off, whereby room
temperature is controlled by controlling the percentage of the duty
cycles.
7. A method of controlling an under surface cooling in which a room
is cooled using a supply loop in which liquid is circulated for
cooling the room, the method comprising decreasing room temperature
by increasing the flow of the liquid in the supply loop, and in
response to a set-point change greater than a pre-determined value,
decreasing temporarily the supply temperature of the liquid.
8. A method according to claim 7, comprising supplying warmer
liquid to the loop before reaching the set point for reducing
overshoot.
9. A hydronic heating/cooling system comprising a main supply pipe,
a main return pipe, at least one supply manifold, at least one
return manifold, heating loops from the supply manifold to the
return manifold, actuators for controlling the flow in the heating
loops arranged to the supply manifold and/or the return manifold
and a control unit including means for controlling the actuators
for controlling the flow of the liquid in the supply loop, means
for temporarily increasing the supply temperature of the liquid in
heating mode and/or means for temporarily decreasing the supply
temperature of the liquid in cooling mode in response to a
set-point change greater than a pre-determined value.
10. A system according to claim 9, wherein the control unit
comprises means for controlling cooler liquid to be supplied to the
loop before reaching the set point in heating mode and/or for
controlling warmer liquid to be supplied to the loop before
reaching set point in cooling mode for reducing overshoot.
11. A system according claim 9, wherein that the actuators are
arranged to control the flow in the heating loops on and off such
that during the duty cycle the flow is high and between the duty
cycles the flow is off.
12. A software product of a control system of a hydronic heating
system in which liquid is led along a main pipe to supply manifold
and distributed in the manifold into heating loops, the heating
loops returning a return manifold, at least one of the manifolds
having actuators for controlling the flow in the heating loops,
wherein the execution of the software product on a control unit of
the control system is arranged to provide the following operations
of increasing room temperature by increasing the flow of the liquid
in the supply loop and, in response to a set-point change greater
than a pre-determined value increasing temporarily the supply
temperature of the liquid.
13. A software product of a control system of a hydronic cooling
system in which liquid is led along a main pipe to a supply
manifold and distributed in the manifold into heating loops, the
heating loops returning to a return manifold, and at least one of
the manifolds having actuators for controlling the flow in the
heating loops, wherein the execution of the software product on a
control unit of the control system is arranged to provide the
following operations of decreasing room temperature by increasing
the flow of the liquid in the supply loop and in response to a
set-point change greater than a pre-determined value decreasing
temporarily the supply temperature of the liquid.
14. A method according to claim 2, comprising supplying cooler
liquid to the loop before reaching the set point for reducing
overshoot.
15. A system according claim 10, wherein that the actuators are
arranged to control the flow in the heating loops on and off such
that during the duty cycle the flow is high and between the duty
cycles the flow is off.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a method of controlling an under
surface heating in which a room is heated using a supply loop in
which liquid is circulated for heating the room, the method
comprising increasing room temperature by increasing the flow of
the liquid in the supply loop.
[0002] The invention further relates to a method of controlling an
under surface cooling in which room is cooled using a supply loop
in which liquid is circulated for cooling the room, the method
comprising decreasing room temperature by increasing the flow of
the liquid in the supply loop.
[0003] Yet further the invention relates to a hydronic
heating/cooling system comprising a main supply pipe, a main return
pipe, at least one supply manifold, at least one return manifold,
heating loops from the supply manifold to the return manifold,
actuators for controlling the flow in the heating loops arranged to
the supply manifold and/or the return manifold and a control unit
comprising means for controlling the actuators for controlling the
flow of the liquid in the supply loop.
[0004] Yet further the invention relates to a software product of a
control system of a hydronic heating system in which liquid is led
along a main pipe to supply manifold and distributed in the
manifold into heating loops, the heating loops returning to a
return manifold, at least one of the manifolds having actuators for
controlling the flow in the heating loops.
[0005] Yet further the invention relates to a software product of a
control system of a hydronic cooling system in which liquid is led
along a main pipe to a supply manifold and distributed in the
manifold into heating loops, the heating loops returning to a
return manifold, and at least one of the manifolds having actuators
for controlling the flow in the heating loops.
[0006] Heating systems typically have different set temperatures
over the day or week. The energy loss from a heated body is
proportional to the ambient temperature difference. It is therefore
possible to save energy by lowering the temperature of a room, for
example, during the night when the room is not occupied. In a
hydronic under surface heating system, when the temperature is
raised back to comfort level, typically the flow of the supply loop
is increased. An under floor heating system is quite a slow system.
Thus, typically quite a long time, for example several hours, is
needed to raise the temperature from the lower value to a comfort
temperature. Further, the heat-up time depends on the energy loss
of the room which for its part depends on outside temperature.
Different gain curves depending on outside temperature could be
used for compensating the outside temperature. However, this kind
of compensation is extremely complicated for transitions between
different temperatures.
[0007] The document JP 11 182 865 discloses a solution in which
water is heated by primary paths and floor is heated by secondary
paths. Thermistors detect the heat on the primary and secondary
paths and control water by control valves. The first thermistor is
set to a target temperature during rapid heating operation. After
reaching switching temperature, rapid heating is stopped and the
second thermistor is set to a second target temperature. The
document JP 57 077 837 discloses a control system of floor heating.
The feeding amount of a fuel to a boiler at the time of initiation
of heating is increased. The document JP 57 062 330 discloses a
control system for floor heater. At the start of heating, in order
to accelerate the rise of heating, the boiler is operated at a
large input and the maximum hot water temperature so as to raise
the surface temperature of the heater.
BRIEF DESCRIPTION OF THE INVENTION
[0008] The object of the invention is to provide a new method and
arrangement for controlling under surface heating/cooling.
[0009] The method of the invention relating to the under surface
heating is characterized by, in response to a set-point change
greater than a pre-determined value, increasing temporarily the
supply temperature of the liquid.
[0010] Further, the method of the invention relating to the under
surface cooling is characterized by, in response to a set-point
change greater than a pre-determined value, decreasing temporarily
the supply temperature of the liquid.
[0011] The system of the invention is characterized in that the
control unit comprises means for temporarily increasing the supply
temperature of the liquid in heating mode and means for temporarily
decreasing the supply temperature of the liquid in cooling mode in
response to a set-point change greater than a pre-determined
value.
[0012] The software product of the invention relating to the under
surface heating is characterized in that the execution of the
software product on a control unit of the control system is
arranged to provide the following operations of increasing room
temperature by increasing the flow of the liquid in the supply loop
and, in response to a set-point change greater than a
pre-determined value increasing temporarily the supply temperature
of the liquid.
[0013] Further, the software product of the invention relating to
the under surface cooling is characterized in that the execution of
the software product on a control unit of the control system is
arranged to provide the following operations of decreasing room
temperature by increasing the flow of the liquid in the supply loop
and in response to a set-point change greater than a pre-determined
value decreasing temporarily the supply temperature of the
liquid.
[0014] In the invention, during a heating mode, room temperature is
increased by increasing the flow of the liquid in a supply loop. If
the set point has an increase that is greater than a pre-determined
value, the supply temperature of the liquid is increased. Thus, a
boost mode is activated for raising the temperature. This provides
the advantage that the step response of the room temperature is
faster, i.e., the room temperature is raised faster. By reducing
the heat-up time, energy is saved, because the average room
temperature could be decreased by fast transitions when increasing
the temperature. The solution also provides improved comfort.
[0015] In an embodiment, the zones with the latest set-point
changes are prioritized by the controller for a period of time or
until the set points are reached. This further speeds up the
raising of the temperature in these zones whereby the heating of
the other parts is not essentially disturbed.
[0016] In another embodiment, cold liquid is supplied to the loop
in the last stage before reaching the new set point. This feature
reduces or minimizes the overshoot and the heating ramp can also be
steep close to the set point. Thus, the heating time can be reduced
and overshoot minimized.
[0017] In a yet another embodiment, previous transitions and
outside temperatures are analyzed and the transition ramps are
optimized on the basis of the analysis. This feature further
increases the speed of the transition and reduces overshoot.
BRIEF DESCRIPTION OF THE FIGURES
[0018] Some embodiments of the invention are described in greater
detail in the attached drawing in which
[0019] FIG. 1 is a schematic of a hydronic heating/cooling
system.
[0020] FIG. 2 shows schematically the temperature of a room,
and
[0021] FIG. 3 shows schematically the temperature of supply
liquid.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 shows a hydronic heating/cooling system. In the
system, liquid is led along a main supply pipe 1 to a supply
manifold 2. The supply manifold 2 distributes the liquid to several
heating loops 3. The heating loops 3 make the liquid to flow
through the rooms or spaces to be heated or cooled. If the system
is used for heating, the liquid can be warm water, for example. On
the other hand, if the system is used for cooling the liquid
flowing in the pipes is cool liquid that cools the rooms or
spaces.
[0023] The pipes forming the heating loops 3 return to a return
manifold 4. From the return manifold 4, the liquid flows back again
along a main return pipe 5.
[0024] Actuators 6 are arranged to the return manifold 4. The
actuators 6 control the flow of the liquid in the loops 3.
[0025] A control unit 7 controls the operation of the actuators 6.
The actuators 6 can also be arranged to the supply manifold 2.
Further, there can be actuators both in the supply manifold 2 and
in the return manifold 4. Either one of the manifolds 2 and 4 can
further comprise balancing valves. The balancing valves can be
manually operated, for example.
[0026] The system can also comprise a circulation pump 8 and a
connection between the main supply pipe 1 and the main return pipe,
the connection being provided with a mixing valve 11. A separate
circulation pump 8 and/or a connection between the pipes 1 and 5
is, however, not always necessary.
[0027] The control unit 7 measures the temperature of the liquid by
a temperature sensor 9. The outside temperature is also measured by
a temperature sensor 10. The control unit 7 can control the
temperature of the liquid in the main flow pipe 1, i.e., the supply
temperature of the liquid, on the basis of the outside temperature,
for example. The control unit 7 can control the temperature of the
liquid in the main flow pipe 1 by controlling the mixing valve 11,
for example.
[0028] The control unit 7 can comprise a zone controller part that
controls the actuators 6 and the circulation pump and a primary
controller part which controls the mixing valve 11, for example. In
such a case, the zone controller part and the primary controller
part are connected by a bus, for example.
[0029] The room thermostats 12 are positioned in the rooms to be
heated. The temperature in the rooms is measured by the thermostats
and the information is led to the control unit 7. The user can also
adjust the set point of the temperature by the thermostats 12. The
set points can also be adjusted by another adjuster or by a
programmed pattern.
[0030] A hydronic under floor heating system distributes the needed
heating to each room in the building by controlling the hot water
flow through a heating loop or supply loop in the floor. Normally,
one loop per room is used but sometimes a large room is split into
two or more loops. A controller will act on the information from
the room thermostat and accordingly turn the water flow on or off
in the floor loop.
[0031] The floor loop or heating loop piping is typically made of
cross-linked polyethylene plastic pipes, for example. These pipes
can be used in different types of floor constructions, i.e., both
concrete and wooden floors can be heated this way. It is essential
that the insulation, under the pipes, in the floor construction is
good to avoid the leakage of energy out downwards. The floor loop
layout depends on the heat demand for each room.
[0032] In a concrete floor, typically 20-mm pipes are used, the
pipes being usually attached to a re-enforcing net before the final
concrete casting. The recommendation is that the top of the pipes
should be 30 to 90 mm below the concrete surface and the pipe loops
should be placed at a 300-mm center distance. Concrete conducts
heat well, so this layout will lead to an even distribution of
energy and give an even temperature on the floor surface. This
building method using concrete and 20-mm pipes is an economical way
of building a UFH (underfloor heating) system.
[0033] Due to the good thermal conduction in concrete, the loop can
be fed with low supply temperature, normally below 35 degrees
Celsius.
[0034] The step response is quite slow due to the large mass of the
floor, normally between 8 to 16 h depending on the floor
thickness.
[0035] In wooden floors there are some different construction
techniques available and we can divide them into two main
categories: floor loops inside the floor construction or on top of
the floor construction. It is to be noted that all UFH wood
construction techniques use aluminum plates to distribute the heat
from the pipes. This compensates for the poor heat conduction in
wood. Generally speaking, all "in floor" constructions use 20-mm
pipes and the "on floor" technique uses 17-mm pipes that are
mounted in pre-grooved floorboards. However, it is self-evident to
a person skilled in the art that the diameter of the pipes can also
be different and it is determined according to the need and/or
requirements set by the system and/or environment.
[0036] Due to the poor thermal conduction in a wooden floor, the
loops need a higher supply temperature than a concrete floor,
normally up to 40 degrees Celsius.
[0037] The step response is quicker than for concrete, normally
between 4 to 6 h depending on the floor construction.
[0038] The previously mentioned systems are primarily installed
when a house is built. In addition to these, there are UFH systems
for after installation. This system focuses on a low building
height and the ease of handling, and uses smaller pipe diameters,
and the pipes are mounted in pre-grooved polystyrene floor panels.
The supply temperature and step response are quite similar to those
of wooden constructions.
[0039] The stroke cycle of the actuator is preferably less than 120
seconds. The actuator can be a conventional mechanical piston
valve. The actuator can also be, for example, a solenoid valve.
When using a solenoid valve, the stroke time of the actuator can be
very short. Thus, the stroke time or operating time of the actuator
can be for example in the range of 0.1 to 120 seconds. Preferably
actuators with fast operating time are used. Thus, the operating
time of the actuators is preferably less than 10 seconds.
[0040] In the control system, the term "pulse width" refers to the
on time of the flow, i.e., the duty cycle. A minimum pulse width is
preferred in order to achieve efficient heating. However, the
minimum pulse width is preferably determined such that during the
duty cycle the longest loop is also filled with supply water. The
minimum pulse width means that the time frame of the control is
quite short, which means high frequency. Preferably, the time frame
is shorter than 1/3 of the response time of the floor in the room
to be heated. The time frame may vary for example between 5 and 60
minutes. In order to achieve the feature that the duty cycles start
at different moments in different loops, the length of the
off-times between the duty cycles can be varied using a pattern or
randomly. The variation must naturally be carried out within
certain limits, such that the percentage of the duty cycles can be
kept at a desired value. Another option is to vary the pulse width
using a pattern or randomly in a corresponding manner. Yet another
option is to use different time frames in different loops. For
example, in one loop the time frame can be 29 minutes, in a second
loop the time frame can be 30 minutes, and in third loop the time
frame can be 31 minutes. Of course sometimes the duty cycles start
simultaneously in different loops, but using at least one of the
above-mentioned systems, the duty cycles start at different moments
in most cases. Thus, the object is to prevent the duty cycles in
different loops from running synchronously.
[0041] The percentage of the duty cycle means how long the on-state
of the time frame is. In other words, if the time frame is 10
minutes and the percentage of the duty cycle is 10%, it means that
the flow is on for 1 minute and off for 9 minutes, if the
percentage is 50 the flow is on for 5 minutes and off for 5 minutes
and if the percentage of the duty cycle is 90, the flow is on for 9
minutes and off for 1 minute off. If the time frame is short
enough, control can be considered continuous if the system is slow
enough, i.e., the response time of the floor is long.
[0042] This specification refers to hydronic under surface
heating/cooling. In such a system, liquid is supplied to supply
loops for cooling/heating. The liquid can be for example water or
any other suitable liquid medium. The liquid may comprise glycol,
for example. Under surface heating/cooling means that the supply
loops are installed under the floor, for example. The supply loops
can also be installed in any other suitable structure. The loops
may be installed in the wall or ceiling, for example.
[0043] In an embodiment an on/off control is combined with pulse
width modulation per room. The pulse width depends on the response
in the room. At the startup the pulse width is preferably always
50%. The time frame for the pulse width can be 30 minutes, for
example. It is important to prevent the different channels/loops
from running synchronously. Adding a random value of -30 to +30
seconds to the time frame can prevent this. Another possibility is
to have a slightly different time frame for each channel/loop. It
is enough if the difference is 5 seconds, for example.
[0044] The maximum value for the pulse width is 25 minutes and the
minimum value is 5 minutes. The resolution can be 1 minute, for
example. Preferably, the pulse width modulation counter is reset
the by a change of a set point which prevents delays in the
system.
[0045] A heating cycle is defined as the time between one heating
request and the next heating request.
[0046] Maximum and minimum room temperatures are monitored and
saved during a full heating cycle.
[0047] The pulse width is adjusted at timeout, at heat-up modes or
after a heating cycle.
[0048] The master timeout for pulse width adjustment can be for
example 300 minutes.
[0049] The control system comprises an appropriate means for
performing the desired functions. For example, a channel block
calculates the control signal based on the set point, the room
temperature and the energy required. The energy is pulse width
modulated and the energy requirement is calculated by measuring the
characteristics of the room temperature over time.
[0050] One way to describe this is that it is a traditional on/off
control with self-adjusting gain.
[0051] In an embodiment, the pulse width modulation output can be
adjusted between 15 to 70% of the duty cycle. The start value is
50%. The maximum and minimum values during an on/off cycle are
stored and evaluated and the duty cycle is adjusted if needed.
[0052] The pulse width modulation timer is restarted if the set
point increases more than 1 degree.
[0053] The curve A in FIG. 2 shows how the temperature in one room
changes if the procedure described below is used during a heating
mode. The new set point T.sub.set is larger than a pre-determined
value. The request to raise the temperature can come from a room
thermostat 12 adjusted by the end-user, for example. The set-point
change can be larger than 3 degrees, for example. This activates
the boost mode, which means that the supply temperature of the
liquid is increased. For example, it is beforehand determined that
the new set point must be reached at six o'clock in the morning.
The moment when the set point must be reached is shown in FIG. 2
with reference sign t.sub.3. In a conventional system the rising of
the temperature would follow curve B, which is shown with a dash
and dot line. Thus, in a conventional system the rising of the
temperature takes quite a long time from the moment t.sub.0 to the
moment t.sub.3.
[0054] Now, however, the supply temperature of the liquid is
increased and it is possible to start the heating period at the
moment t.sub.1. Thus, the rising of the temperature in the room
happens rather fast.
[0055] However, the rise of the ramp is steep, which means that an
overshoot, which is denoted with a dash and dot line C in FIG. 2,
easily occurs. This overshoot can be reduced or minimized by
lowering the supply temperature before the set point is
reached.
[0056] FIG. 3 illustrates the supply temperature of the liquid
during a heating mode. The ripple in the curve illustrates that the
control unit 7 adjusts the supply temperature on the basis of the
outside temperature. At the moment t.sub.1 the supply temperature
is increased by adjusting the mixing valve 11, for example. At the
moment t.sub.2 the supply temperature is lowered. Thus, after the
moment t.sub.2 cooler supply liquid is supplied. The room is not
cooled but it is heated less between the moments t.sub.2, and
t.sub.3 than between the moments t.sub.1 and t.sub.2. If only the
mixing valve 11 is controlled, the supply temperature lowers
according to the curve shown by the broken line D. Thus, the supply
temperature lowers quite slowly. This means that the room
temperature would act according to the line E in FIG. 2.
[0057] However, if the supply temperature is lowered faster than
shown by the curve in FIG. 3 with a solid line, it is possible to
start lowering the temperature at the moment t.sub.2. The supply
temperature of the liquid can be cooled by opening temporarily at
least some of the actuators 6 of the other loops 3, which are not
boosted. If there have been no heat calls in these loops, these
loops contain liquid having lower temperature than the liquid in
the boosted loop. These loops need to be opened only for a short
time. If this time is less than 10 minutes, for example, this does
not substantially raise the temperature in the rooms through which
these loops pass.
[0058] The supply temperature between the moments t.sub.2 and
t.sub.3 can be lower than the normal supply temperature before
boosting. At the moment t.sub.3 the supply temperature can be
raised to a normal level.
[0059] During a cooling mode a corresponding procedure is used. It
is, however, self-evident that then room temperature is decreased
by increasing the flow of liquid in the supply loop and, in
response to a set-point change greater than a pre-determined value,
decreasing temporarily the supply temperature of the liquid. The
overshoot is reduced by supplying warmer liquid to the loop before
reaching the set point.
[0060] The control unit 7 can comprise a software product whose
execution on the control unit 7 is arranged to provide at least
some of the above-described operations. The software product can be
loaded onto the control unit 7 from a storage or memory medium,
such as memory stick, a memory disc, a hard disc, a network server,
or the like, the execution of which software product in the
processor of the control unit or the like produces operations
described in this specification for controlling a hydronic
heating/cooling system.
[0061] In some cases the features described in this application can
be used as such regardless of other features. The features
described in this application may also be combined as necessary to
form various combinations.
[0062] The drawings and the related description are only intended
to illustrate the idea of the invention. The invention may vary in
detail within the scope of the claims.
* * * * *