GB2318179A - Pump control for central heating systems - Google Patents

Pump control for central heating systems Download PDF

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Publication number
GB2318179A
GB2318179A GB9621219A GB9621219A GB2318179A GB 2318179 A GB2318179 A GB 2318179A GB 9621219 A GB9621219 A GB 9621219A GB 9621219 A GB9621219 A GB 9621219A GB 2318179 A GB2318179 A GB 2318179A
Authority
GB
United Kingdom
Prior art keywords
pump
speed
control arrangement
heat exchanger
outlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9621219A
Other versions
GB9621219D0 (en
Inventor
Leslie Hammond
David Broadbent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BLUE CIRCLE HEATING Ltd
Original Assignee
BLUE CIRCLE HEATING Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BLUE CIRCLE HEATING Ltd filed Critical BLUE CIRCLE HEATING Ltd
Priority to GB9621219A priority Critical patent/GB2318179A/en
Publication of GB9621219D0 publication Critical patent/GB9621219D0/en
Publication of GB2318179A publication Critical patent/GB2318179A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/0005—Control, e.g. regulation, of pumps, pumping installations or systems by using valves
    • F04D15/0016—Control, e.g. regulation, of pumps, pumping installations or systems by using valves mixing-reversing- or deviation valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/0066—Control, e.g. regulation, of pumps, pumping installations or systems by changing the speed, e.g. of the driving engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/44—Fluid-guiding means, e.g. diffusers
    • F04D29/46—Fluid-guiding means, e.g. diffusers adjustable
    • F04D29/48—Fluid-guiding means, e.g. diffusers adjustable for unidirectional fluid flow in reversible pumps
    • F04D29/486—Fluid-guiding means, e.g. diffusers adjustable for unidirectional fluid flow in reversible pumps especially adapted for liquid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D19/00—Details
    • F24D19/10—Arrangement or mounting of control or safety devices
    • F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
    • F24D19/1066—Arrangement or mounting of control or safety devices for water heating systems for the combination of central heating and domestic hot water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2260/00—Function
    • F05B2260/96—Preventing, counteracting or reducing vibration or noise
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Fluid Mechanics (AREA)
  • Steam Or Hot-Water Central Heating Systems (AREA)

Abstract

A central heating system comprises a main heat exchanger 1 for heating water flowing through it, a reversible pump 5 operable on the hot water output from the heat exchanger 1 for controlling space heating or domestic hot water operation in dependence upon the direction of rotation of the pump 5, and a control arrangement for reducing the speed of said pump before it is reversed in direction for reducing noise problems generated in the pump 5 on changeover by a flexible valve 7. The valve may be of rubber.

Description

Central Heating Svstems This invention relates to central heating systems, and more particularly to central heating systems which incorporate a reversible pump for controlling space heating and domestic hot water operation.
Central heating systems exist which heat water in a main heat exchanger then direct the hot water flow either to radiators for space heating or to a secondary heat exchanger to give hot water for domestic use. The second heat exchanger may be separate from the main heat exchanger or may be incorporated in it. The diverting of the water flow may be achieved by a valve driven by some form of actuator or by a reversible pump, where changing the direction of rotation of the pump causes the water flow to change from one circuit to another.
In such a system, when the pump is caused to change direction a substantial "thurnp" is caused to be emitted when the pump stops, and to a lesser degree when it starts up in the opposite direction. This "thump" is very undesirable and can be very disconcerting to a user.
It is an object of the present invention to provide a central heating system incorporating a reversible pump, in which the effects of said "thump" are reduced.
According to the present invention there is provided a central heating system comprising a heat exchanger for heating water flowing through it, a reversible pump operable on the hot water output from said heat exchanger for controlling space heating or domestic hot water operation in dependence upon the direction of rotation of said pump, and a control arrangement for reducing the speed of said pump before it is reversed in direction.
In carrying out the invention it may be arranged that said control arrangement reduces the speed of said pump in accordance with a step, ramp or any other required function.
In a preferred system according to the present invention it is arranged that said control arrangement is effective for increasing the speed of said pump to an intermediate speed lower than its normal operating speed when the pump is started in a reversed direction.
In carrying out the arrangement according to the preferred system it may be arranged that said control arrangement increases the speed of said pump in accordance with a step, ramp or any other required function.
It may be arranged that said control arrangement is operative on different tapping points on the motor of said pump for controlling its speed, or alternatively is effective for electronically controlling the power supplied to said pump for controlling its speed.
An exemplary embodiment of the invention will now be described, reference being made to the accompanying drawings, in which: Figure 1, is a schematic representation of a conventional central heating system incorporating a reversible pump; Figures 2, 3 and 4, are schematic representations of the reversible pump of Figure 1 which illustrate its operation; and Figure 5, is a graph illustrating a preferred changeover sequence in accordance with the present invention for the reversible pump of Figure 1.
The central heating system shown in Figure 1 of the drawings comprises a main heat exchanger 1 which is heated by a gas burner 2 for causing water flowing through the heat exchanger 1 via an inlet pipe 3 and an outlet pipe 4 to be heated. The outlet pipe 4 of the main heat exchanger 1 is connected to the common input A of a reversible, 2-outlet pump 5 having two outlets B and C.
The reversible pump 5 incorporates an impeller 6 driven by an electric motor (not shown), which directs hot water from the common inlet A towards the outlet B or the outlet C dependent upon the direction of the rotation of the impeller 6.
The pump 5 also incorporates a flexible valve 7, typically of rubber, which is pivotally mounted in the casing (not shown) of the pump 5 and which in one position thereof, as shown in Figure 1, makes sealing engagement with the outlet C of the pump 5 thereby preventing water flow from the common inlet A to the outlet C, and in another position thereof, as shown in dashed lines in Figure 1, makes sealing engagement with the outlet B of the pump 5 thereby preventing water flow from the common inlet A to the outlet B. The positional control of the valve 7 of the pump 5 is determined by the direction of rotation of the impeller 6 as will be described with reference to Figures 2 to 4.
Outlet B of the pump 5 is connected via the "flow" pipe 8 to one or more central heating radiators (not shown) the "return" pipe 9 being connected to the inlet pipe 3 of the main heat exchanger 1.
Outlet C of the pump 5 is connected to a secondary "domestic water" heat exchanger 10 the output pipe 11 of which is also connected to the inlet pipe 3 of the main heat exchanger 1, the secondary heat exchanger 10 being effective for heating domestic water flowing through it via input and output pipes 12 and 13 respectively.
In Figure 1 the secondary heat exchanger 10 is separate from the main heat exchanger 1, but it should be appreciated that it could be incorporated in the main heat exchanger 1 in well known manner.
The operation of the reversible pump 5 of Figure 1 to control hot water flow to the outlet B thereof to the one or more radiators or the outlet C to the secondary "domestic water" heat exchanger 10 for obtaining domestic hot water will now be described with reference to Figures 2, 3 and 4.
In Figure 2, it is arranged that the impeller 6 of the pump 5 is driven in an anticlockwise direction, which causes the valve 7 to be moved towards the right as viewed in the drawing so as to make sealing engagement with the outlet C of the pump 5, thereby blocking outlet C so that water flow takes place from the common inlet A to the outlet B and thence to the one or more radiators (not shown) as described with reference to Figure 1.
In Figure 2, the position of the valve 7 is shown when the impeller 6 is stationary. In this position the valve 7, due to its resilience, adopts a position midway between outlet B and outlet C.
In Figure 3, it is arranged that the impeller 6 of the pump 5 is driven in a clockwise direction, which causes the valve 7 to be moved towards the left as viewed in the drawing so as to make sealing engagement with the outlet B of the pump 5 thereby blocking outlet B so that water flow takes place from the common inlet A to the outlet B and thence to the secondary "domestic water" heat exchanger 10 as described with reference to Figure 1.
It has been found that in a system as described with reference to Figures 1 to 4 that when the pump 5 is operating and when a change of demand for hot water or central heating or vice-versa is made, the change of direction of the pump 5 which effects this causes a substantial "thump" to be emitted from the valve when it stops and also, to a lesser degree, when it starts up again. This "thump" is very undesirable and can be very disconcerting to a user.
It has also been ascertained that the generation of the "thump" can be explained as follows: Referring to Figure 2, when the pump 5 is operating the valve 7 is held on the seat constituted by outlet C due to the force exerted by the rotating mass of water emerging from the impeller 6 and there is considerable momentum in the mass of water flowing from the inlet A through the outlet B and around the circuit. When the impeller 6 is stopped, the force due to rotation is removed from the valve 7 but the momentum of the flow remains. This pulls the valve 7 across to the seat constituted by outlet B, sealing it abruptly, and causing the "thump". For similar reasons a "thump" is also generated when the impeller 6 is started up again.
In accordance with the present invention it has been found that the generation of the "thumps" as described can be virtually eliminated by the use of the speed control on the pump 5.
Figure 6 of the drawings is a graph depicting a possible pump speed versus time characteristic for effecting flow changeover.
Assuming that the pump 5 is operating at "Full" speed in the clockwise direction, at time (a), the speed of the pump 5 is reduced to a "Low" speed and is held at this speed until it is stopped at time (b). After a further period, at time (c) the pump is restarted in the anticlockwise direction at a "Low" speed and is held at this speed until time (d) when the speed of the pump is increased to "Full".
The effect of this changeover is that the selection of the "Low" speed reduces the flow speed, and therefore the momentum but holds the valve 7 in place. The reduced momentum is not enough to pull the valve 7 over to the other outlet, and the "thump" is eliminated. "Low" speed starting reduces the force with which the valve 7 closes, and eliminates the "thump" on start up.
The speed of the pump 7 may be controlled by a suitable control arrangement operable on the pump motor such as by selectively energising different tapping points on the motor windings, or by electronic variation of the power supplied to the motor.
Although in the arrangement described with reference to Figure 6 speed change is effected in accordance with a step function, a ramp function or any other function may be used, and the times and precise speeds may be optimised to afford minimum changeover times with little or no noise.

Claims (9)

1. A central heating system comprising a heat exchanger for heating water flowing through it, a reversible pump operable on the hot water output from said heat exchanger for controlling space heating or domestic hot water operation in dependence upon the direction of rotation of said pump, and a control arrangement for reducing the speed of said pump before it is reversed in direction.
2. A system as claimed in claim 1, in which said control arrangement reduces the speed of said pump in accordance with a step function.
3. A system as claimed in claim 1, in which said control arrangement reduces the speed of said pump in accordance with a ramp function.
4. A system as claimed in any preceding claim, in which said control arrangement is effective for increasing the speed of said pump to an intermediate speed lower than its normal operating speed when the pump is started in a reversed direction.
5. A system as claimed in claim 4, in which said control arrangement increases the speed of said pump in accordance with a step function.
6. A system as claimed in claim 4, in which said control arrangement increases the speed of said pump in accordance with a ramp function.
7. A system as claimed in any preceding claim, in which said control arrangement is operative on different tapping points on the motor of said pump for controlling its speed.
8. A system as claimed in any of claims 1 to 6, in which said control arrangement is effective for electronically controlling the power supplied to said pump for controlling its speed.
9. A system substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.
GB9621219A 1996-10-11 1996-10-11 Pump control for central heating systems Withdrawn GB2318179A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9621219A GB2318179A (en) 1996-10-11 1996-10-11 Pump control for central heating systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9621219A GB2318179A (en) 1996-10-11 1996-10-11 Pump control for central heating systems

Publications (2)

Publication Number Publication Date
GB9621219D0 GB9621219D0 (en) 1996-11-27
GB2318179A true GB2318179A (en) 1998-04-15

Family

ID=10801264

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9621219A Withdrawn GB2318179A (en) 1996-10-11 1996-10-11 Pump control for central heating systems

Country Status (1)

Country Link
GB (1) GB2318179A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1054218A1 (en) * 1999-05-17 2000-11-22 Daewoo Electronics Co., Ltd Two-way pump for gas boiler, control circuit thereof, and control method thereof
EP3037669A1 (en) * 2014-12-22 2016-06-29 Grundfos Holding A/S Hydraulic system
EP3037670A1 (en) * 2014-12-22 2016-06-29 Grundfos Holding A/S Hydraulic system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0460399A2 (en) * 1990-05-04 1991-12-11 Grundfos International A/S Centrifugal pump and gasboiler including the same
US5486089A (en) * 1994-02-28 1996-01-23 Daewoo Electronics Co., Ltd. Directional changeover pump

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0460399A2 (en) * 1990-05-04 1991-12-11 Grundfos International A/S Centrifugal pump and gasboiler including the same
US5486089A (en) * 1994-02-28 1996-01-23 Daewoo Electronics Co., Ltd. Directional changeover pump

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1054218A1 (en) * 1999-05-17 2000-11-22 Daewoo Electronics Co., Ltd Two-way pump for gas boiler, control circuit thereof, and control method thereof
EP3037669A1 (en) * 2014-12-22 2016-06-29 Grundfos Holding A/S Hydraulic system
EP3037670A1 (en) * 2014-12-22 2016-06-29 Grundfos Holding A/S Hydraulic system
WO2016102271A1 (en) * 2014-12-22 2016-06-30 Grundfos Holding A/S Hydraulic system
WO2016102269A1 (en) * 2014-12-22 2016-06-30 Grundfos Holding A/S Hydraulic system
CN107250556A (en) * 2014-12-22 2017-10-13 格兰富控股联合股份公司 Hydraulic system
CN107407286A (en) * 2014-12-22 2017-11-28 格兰富控股联合股份公司 Hydraulic system
US20170356449A1 (en) * 2014-12-22 2017-12-14 Grundfos Holding A/S Hydraulic system
US10443860B2 (en) 2014-12-22 2019-10-15 Grundfos Holding A/S Hydraulic system
US10677249B2 (en) 2014-12-22 2020-06-09 Grundfos Holding A/S Hydraulic system
CN107407286B (en) * 2014-12-22 2020-07-10 格兰富控股联合股份公司 Hydraulic system
CN107250556B (en) * 2014-12-22 2020-08-25 格兰富控股联合股份公司 Hydraulic system

Also Published As

Publication number Publication date
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Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)