WO1997017575A1

WO1997017575A1 - Liquid-circulation heating system and pump

Info

Publication number: WO1997017575A1
Application number: PCT/FI1995/000613
Authority: WO
Inventors: Matti Ilmari Kangas
Original assignee: Matti Ilmari Kangas
Priority date: 1994-09-21
Filing date: 1995-11-10
Publication date: 1997-05-15

Abstract

The invention relates to a liquid-circulation heating system and a pump wherein the supply and circulation of the heating liquid is controlled by means of a pressure difference created by thermostatic valves (6). The pressure difference directly controls a circulation pump (5) and a feed pump (4) which have different operating characteristics. Said pumps can be constructed together in such a way that they are located on the same axis or that they have a double-sided rotor wheel.

Description

Liquid-circulation heating system and pump

The invention relates to a liquid-circulation heating system and a pump. The heating system and the pump according to the invention are used in connection with a normal water-circulation central heating system or, for example, a hot-oil system comprising a boiler as a source of heat, flow and return pipes, a pump, actuators provided with thermostatic valves, radiators or a floor-heating network, and a check valve.

The oldest manner of regulating the water circulation of a water central heating network is a system that is based on the temperature difference of water and that utilizes no circulation pumps. However, modern buildings are designed in such a way that gravity-based circulation of the radiator network is not possible, but the heating systems utilize circulation pumps. The use of a circulation pump naturally reduces the size of the piping and the radiators, and the pipes are easier to install.

The most common system for regulating the water temperature used in the circulation of the radiator network has been a system with a three-way valve. A three-way valve is used to control the water circulating in the radiator network and the hot water coming from the boiler. Such a system normally comprises a circulation pump, but it may also be provided with two separate pumps for the circulation of water and for the boiler. The control of the three-way valve and the impulses for its regulation can in principle be implemented in several ways. One of the most complete implementations is naturally to measure the temperature of the water flowing to the radiators in the places of consumption, as well as the temperature of the water leaving the radiators, the temperature of the room and the outside temperature, and by means of the aforementioned temperatures to determine and adjust the position required in each case for the three-way valve. Taking into account the matters aiming at saving energy, lengthening the operating life of the boiler and preventing corrosion easily leads to a rather complicated control system which increases the costs of the heating system.

Different hot-water heating systems or the like, which aim at disposing of the three-way valve, have been developed and studied to some extent. An arrangement of this type is disclosed in Swiss Patent 536,465 describing a heating system in which the radiator network is provided with a pump for the hot water coming from the boiler and with a circulation pump, the pumps being regulated by means of a separate control system that measures the temperature of the water going to the radiators and returning to the boiler. The actual control is performed by changing the speed of rotation of the pumps.

Known control systems that are used for the regulation of the radiator network are often rather costly and are not very well applicable to smaller places, such as the heating systems of detached or terraced houses. The control systems that are presently used do not react very well in heating systems where each radiator is adjusted separately by means of thermostatic valves. A system which takes into account the outside temperature is insensitive for example in cases where one or several rooms are temporarily adjusted to a temperature that is considerably lower than the normal room temperature. The liquid-circulation heating system and the pump according to the invention provide sufficient control characteristics which take fully into account the control of the thermostats that are specific to each radiator.

The invention is based on the fact that the feed pump and the circulation pump of the radiator network are different, whereupon a pressure difference caused by the thermostatic valves controls the quantity of flow passing through the pumps, and sufficient control is thus obtained for the heating network. To be accurate, the liquid-circulation heating system and the pump according to the invention are characterized by what is disclosed in the characterizing portion of claim 1. The invention provides significant advantages over the conventional systems. The liquid-circulation heating system and the pump according to the invention can be applied to a conventional hot-water radiator heating system, a hot-oil heating system or to other corresponding systems. The actual heating may be provided by means of a radiator or floor network, or air heating. The system according to the invention requires no control valves for the circulating water or for the feed water coming from the boiler. Thermostatic valves that are specific for each room or radiator control the heating equipment. Since the adjustment is performed on the basis of a pressure difference in the network, it always occurs in real time, and a possible delay caused by a change in the outside temperature does not have to be taken into account in the temperature of the radiator network. The pump according to the invention can be implemented in such a way that the feed pump and the circulation pump of the radiator network are connected to the same electric motor on the same axis, and only the delivery heights and the flow curves of the pumps differ. The system according to the invention also takes into account the requirements created by the corrosion of the boiler, and when the system is being designed, it is possible to determine the temperature of the boiler return water under all circumstances.

In the following, the invention will be described in greater detail with reference to the accompanying drawings.

Figure 1 shows the pipe circuit according to the invention.

Figure 2 shows the pressure/flow curves of the feed water and circulation pumps. In Figure 1, a boiler is denoted with reference numeral 1, a feed pipe of the radiator network arriving from the boiler with reference numeral 2, and a return pipe with numeral 3. A feed pump is denoted with reference numeral 4, and a circulation pump with numeral 5. Thermostatic valves are denoted with reference numeral 6, and actuators, such as radiators or the like, with reference numeral 7. A circulation pipe situated between the feed pipe and the return pipe is denoted with reference numeral 8, and a check valve located in the return pipe of the boiler with reference numeral 9.

In the liquid-circulation heating system circuit of Figure 1, the feed pump 4 pumps hot water from the boiler 1, and the circulation pump 5 circulates the cool return water to the radiator network 7. The temperature of the water coming from the feed pipe 2 and the circulation pipe 8, as well as the proportion of the water amounts, determine the temperature of the water supplied to the radiator network. The pumps 4 and 5 operate in the heating system of the invention in the same way as a three-way valve. The check valve 9 provided in the return pipe 3 prevents flow in the wrong direction in the boiler and the pipes. The thermostatic valves 6 are used to control the water flow to the radiator network 7 according to the needs of an individual house and a radiator or a room, whereupon the pressure difference in the radiator network and simultaneously in each pump 4 and 5 changes. The pressure difference increases when the need for heating decreases and the thermostatic valves are closed. The flow of the pumps 4 and 5 changes when the pressure difference alters. The pumps 4 and 5 are designed in such a way that the pump 4 has a high yield but a low delivery height. The pump 5 in turn has a low yield but a great delivery height. The pressure/flow curves of the pumps are shown in Figure 2, wherein curve 1 is the operating characteristic of the pump 4, and curve 2 is the operating characteristic of the pump 5. The pressure difference p is shown in the horizontal plane and the quantity of flow q in the vertical plane. In order that the control system of the invention would be simple and easy to implement in practice, the pumps to be used are manufactured on the same axis and to be driven by the same motor.

When the need for heating is great, the thermostatic valves create a slight pressure difference so that the pump 4 pumps a great deal of hot water into the network from the boiler 1. The flow of the pump 5 is considerably smaller, wherefore hot water flows freely to the radiators. When the thermostatic valves 6 begin to close, the flow of both pumps 4 and 5 decreases, but the flow of the pump 4 decreases considerably faster wherefore the temperature of the water flowing to the radiators drops. When the pressure difference becomes great enough, the flow through the boiler 1 ends completely and the water flowing to the radiators 7 is no longer heated. The temperature of the water flowing to the radiator network is regulated in the arrangement of the invention completely according to the temperature required, without any kinds of control valves. The liquid-circulation heating system and the pump according to the invention can naturally also be implemented in some other manner than the one disclosed in the embodiment according to the present application. The location of the pump 4 can be changed in such a way that the pump is placed in the return pipe 3, whereupon the temperature at which the pump operates drops substantially. Fixed orifice plates, manually controlled valves or the like can also be used to affect the pipe resistances and the flow conditions in different parts of the network. The manually controlled valves of the radiators or the like can be used for the basic adjustment of the heating apparatuses. With the aforementioned measures, the selection of pumps to be used in the system can be reduced, since the conditions of the places of use vary quite considerably depending on the buildings and the need for heat.

Claims

1. A liquid-circulation heating system and a pump that are used for circulating and regulating the heating water used in connection with water-circulation water central heating or the like that is provided with radiators or the like, the system comprising a boiler (1), piping (2, 3, 8), pumps (4, 5), radiators (7) or the like, and thermostatic valves (6), c h a r a c¬ t e r i z e d in that the operation of the feed pump (4) and the circulation pump (5) is controlled by means of a pressure difference created by the thermostatic valves (6) or the like, and that said control is based on the different yield and delivery height values of said pumps (4, 5).

2. A liquid-circulation heating system according to claim 1, c h a r a c t e r i z e d in that the feed pump (4) and the circulation pump ( 5) operate in the same way as a three-way valve and adjust the water supplied to the radiators (7) .

3. A liquid-circulation heating system according to claim 1, c h a r a c t e r i z e d in that the system comprises a heating apparatus or thermostatic valves that are known per se and that are specific for each apartment, and the return pipe (3) comprises a check valve.

4. A pump according to claim 1, c h a r a c t e r i z e d in that the feed pump (4) and the circulation pump ( 5 ) are positioned on the same axis to be driven by a common actuator, or that the rotor wheel of said pump operates in two directions and forms the feed and circulation pumps (4, 5).