GB2536463A - System to enable balancing of a central heating system - Google Patents

Abstract

A central heating system 1 comprises a plurality of parallel radiator circuits 2. A feed pipe or inlet 6 supplies heated water to the radiator 2 with an inflow valve 7 connected to the feed pipe 6 to adjust the flow of heated water through the radiator 2 and out through an outlet pipe 8. A flow meter 10 connects to either the feed pipe 6 or the outlet pipe 8 to measure the flow rate of heated water through the radiator 2. Each radiator 2 may comprise an outflow valve connected to the outlet pipe to adjustably restrict the flow rate of water through the radiator. The central heating system may be hydraulically balanced by comparing the flow rate through one or more radiators with a desired nominal flow rate and adjusting the inflow or outflow valve so that the system reaches equilibrium.

Description

System to enable balancing of a central heating system Central heating systems are commonly used in residential properties for maintaining a comfortable living temperature. Central heating systems generally comprise a boiler for heating water, a hydraulic circuit fluidly connected to the boiler and a plurality of radiators arranged in parallel across the hydraulic circuit. Such systems further comprise a pump to circulate heated water from the boiler around the hydraulic circuit and through the radiators. Heat is conducted from the water and into the radiator whereupon is it is conducted and radiated into the room.

In order to ensure efficient operation of a central heating system, it is desirable to obtain an equilibrium in which the total amount of heat delivered by each radiator is the same, or as close to the same as possible. This is known as a 'balanced system'.

In conventional systems, each radiator is equipped with an inflow and an outflow valve that controls the flow rate of heated water through the radiator. Opening up either valve will increase the flow rate of heated water through the radiator having the effect of increasing the amount of heat delivered by the radiator. With radiators arranged in parallel, increasing the flow rate through any single radiator will have the effect of reducing the flow rate through radiators further along the hydraulic circuit, resulting in an imbalance of heat transferred as less heat can be transferred by those radiators with reduced flow.

As well as poorly set valves, blockages in the pipes caused by scale or other detritus can cause radiators to transfer different amounts of heat.

One well known method of balancing a central heating system requires an operator to close the outlet valve to each radiator and to measure the water temperature difference across each radiator consecutively, starting with the radiator closest to the boiler. The temperature difference across a radiator is generally measured by taking a temperature reading of the inflow and outflow pipes and calculating the difference between the readings. In a correctly balanced system, the temperature difference across each radiator should be, as close as possible, the same nominal value. To balance the system, the outlet valve of the first radiator is opened by a small amount at a time to reduce the temperature difference between the inflow and the outflow pipes until the temperature difference is equal to the nominal value. The process is repeated with each consecutive radiator in the system until all the radiators have been adjusted so that the temperature difference across each radiator is the same. It will be appreciated that this process requires the time consuming step of allowing the outflow pipe to reach an equilibrium temperature following each adjustment of the outflow valve so that a representative temperature reading to be taken.

It is an object of the invention to provide a system which substantially reduces the time required to balance a central heating system.

/o According to the present invention, there is provided a central heating system having a plurality of radiator circuits hydraulically connected in parallel, wherein each radiator circuit comprises: a radiator, a feed pipe hydraulically connected to the radiator to provide heated water to the radiator, an inflow valve hydraulically connected to the feed pipe for adjustably restricting the flow rate of water through the radiator, an outlet pipe hydraulically connected to the radiator, so that water that flows through the radiator flows out through the outlet pipe and a flow meter hydraulically connected to either the feed pipe or the outlet pipe to measure the flowrate of water passing though the radiator.

Each radiator circuit may further comprise an outflow valve hydraulically connected to the outlet pipe for adjustably restricting the flowrate of water through the radiator.

It is possible to balance a central heating system by determining the flow rate through each radiator circuit. The system is considered balanced when the flow rate through -0or each radiator circuit is the same. Therefore, the present invention allows the operator to balance a central heating system by establishing the flow rate through each radiator circuit by taking a reading from a respective flowmeter and adjusting either the inflow or outflow valves of each radiator circuit in turn until the flow rate through each radiator circuit is the same.

Therefore, there is provided a method for balancing the central heating system of the present invention, wherein the method includes the steps of: adjusting either the inflow valve or the outflow valve of one or more radiator circuits to adjust the flowrate of water through the associated radiator, determining the new flowrate from the associated flowmeter and comparing this flowrate to a desired nominal flow rate and making any -3 -further adjustment necessary to the inflow valve or the outflow valve to equalise the flowrate indicated by the associated flowmeter with the desired nominal flowrate.

Advantageously, equilibrium flow conditions are achieved instantaneously from the moment of adjusting an outflow valve allowing the operator to obtain a representative flow rate reading as soon as an adjustment is made. This provides the advantage of reducing the time taken for balancing the system over the known method as the operator is not required to wait for temperature equilibrium to be reached.

/o A further advantage of the present invention is that, as the flowmeters are permanently installed, the system can be monitored for any changes that may occur over time that might affect the flow rate. Therefore, the operator may adjust the outflow valve of a radiator in response to a change in the flowrate through the radiator before a noticeable change in the heat output by the radiator occurs.

So that the present invention may be more fully understood embodiments thereof will now be described with reference to the accompanying drawings in which: Figure 1 is a schematic representation of a central heating system according to the present invention.

Figure 1 shows a central heating system 1 according to an embodiment of the present invention, the system 1 comprises a plurality of radiators 2 fluidly connected in parallel to a boiler 3. A pump 4 is provided for circulating water around the hydraulic circuit so -0or that heated water from the boiler 3 is provided to each radiator 2, whereupon heat from the heated water is conducted and radiated into the radiators' 2 surroundings.

In more detail, the system comprises a hot pipe 5 hydraulically coupled to the boiler to carry heated water from the boiler 3 to the plurality of radiators 2. Each radiator 21S hydraulically connected to a feed pipe 6 which branches off the hot pipe 5 at a T junction so that hot water is induced to flow into the feed pipe 6 and into the associated radiator 2. An inflow valve 7 is hydraulically connected to each feed pipe 6 between the corresponding T junction and radiator 2 and is configured to adjustably restrict the flow of water through the radiator 2. An outlet pipe 8 is hydraulically connected to the downstream side of each radiator 2 so that water that flows through the associated radiator 2 flows out of the radiator 2 through the corresponding outlet pipe 8. A -4 -flowmeter 10 is hydraulically connected to each outlet pipe 8 to provide an indication of the rate of flow of water through the associated radiator. Alternatively, the flowmeter 10 may be connected to the feed pipe 6 to provide an indication of the rate of flow of water through the associated radiator 2. Each radiator 2 and corresponding feed pipe 6, corresponding inflow valve 7, corresponding outlet pipe 8 and corresponding flow meter 10 make up a radiator circuit.

The outlet pipes 8 are hydraulically connected by a cold pipe 9 which carries water that has passed through the radiators 2 back to the boiler 3. In the example system 1 shown in Figure 1 the pump 4 is hydraulically connected to the cold pipe 9 to draw water through the system 1. At shall be appreciated that the positioning of the pump 4 is not essential to the invention and may be positioned in any suitable position in the hydraulic circuit; for example, a well-known alternative is to position the pump 4 so that it is hydraulically connected to the hot pipe 5 between the boiler 3 and the first feed pipe 6 so that the pump 4 instead pushes water through the system 1.

The pump 4 generates a steady flow of water through the system 1 which is split between the radiator circuits. The flow rate through each radiator circuit will be proportional to a ratio of the total hydraulic resistance of the system to the hydraulic resistance of the associated radiator circuit, as shown below: Fir R Where Q, is the flow rate through any radiator circuit, Rr is the total hydraulic resistance of the system and 121is the hydraulic resistance of the same radiator circuit.

The total hydraulic resistance is, in part, made up of the individual hydraulic resistances of the radiator circuits and, as the radiator circuits are hydraulically arranged in parallel, an estimate for the total resistance of the system will be given by: 1 1 1 1.

----RT Hi R2 R3 -5 -Therefore, it can be seen that a change in the hydraulic resistance of any one of the radiator circuits will affect the flow rate through all the remaining radiator circuits in the system. For example, increasing the hydraulic resistance of one of the radiator circuits will cause a decrease in the flow rate through that radiator 2 and an increase in the flow rate through the remaining radiators 2.

In the system shown in Figure 1, the hydraulic resistance of the radiator circuits is adjusted by the associated inflow valve 7. Therefore, the flow rate through any given radiator circuit, and therefore through any given radiator 2, is adjusted by the it) associated inflow valve 7. In most central heating systems, radiators are also equipped with an outflow valve and it shall be appreciated that the system depicted in Figure 1 may also comprise an outflow valve and that adjusting either valve will affect the flow rate through the associated radiator. Further, it shall be appreciated that any suitable valve may be used that is operable to adjustably restrict or derestrict flow through the radiator and therefore increase or decrease respectively the hydraulic resistance of the associated radiator circuit. Common valve types suitable for use in the system 1 depicted in Figure 1 include, but are not limited to, manual valves, lockshield valves and thermostatic valves.

As set out above, the flow rate through any given radiator 2 in the system 1 will be proportional to the amount of heat transferred by that radiator 2. For example, increasing the flow rate through any given radiator 2 will increase the amount of heat transferred by that radiator 2. A conventional central heating system is balanced so that the total amount of heat transferred by each radiator in the system is the same, or as close to the same as possible, by adjusting the inflow or outflow valve, taking a temperature reading of the feed pipe and outlet pipe and calculating the difference between the readings. In a correctly balanced system, the temperature difference between the readings for each radiator in the circuit should be, as close as possible, the same nominal value. This temperature difference is an indication of the temperature drop of water passing through the associated radiator and therefore the flowrate of water passing through the associated radiator; for example increasing the flowrate through the associated radiator by adjusting the inflow valve will reduce the temperature difference between readings.

A method of balancing the system depicted in Figure 1 is provided by the present invention. The method includes the step of adjusting any inflow valve 7 so as to have a -6 -corresponding effect on the flowrate through the associated radiator. The method further comprises the steps of determining the new flowrate from the flowmeter 10 provided on the outlet pipe 8 and making any further adjustment necessary to the inflow valve 7 to cause the flow rate to be the same as a nominal flowrate, or as close to a nominal flowrate as possible. Therefore, by measuring the flow rate directly, the step of taking temperature readings of the feed pipe 6 and the outlet pipe 8 is not required. This process is then repeated for each radiator circuit in the system 1.

For the above mentioned reasons, adjusting the flowrate through any radiator circuit will cause a change in the flowrate through the remaining radiator circuits. For this reason, each associated inflow valve 7 may have to be adjusted multiple times in a process of trial and error in order to achieve flowrate equality for each radiator circuit. This same issue applies to the above described known method of balancing the system, in which it is necessary to adjust each radiator circuit in a process of trial and error in order to achieve an equal temperature difference between readings. However, it will be appreciated that the time taken to acquire an equilibrium temperature reading will be restricted by the time taken for the associated pipe to reach a stable temperature. By contrast, the effect of adjustments made to any inflow valve of the system depicted in Figure 1 will be detectable as a change in the flowrate as indicated instantly by the flowmeter 10. Therefore, the time taken to balance a central heating system is greatly reduced by the method of the present invention. -7 -

Claims (3)

1. Claims 1. A central heating system having a plurality of radiator circuits hydraulically connected in parallel, wherein each radiator circuit comprises: a radiator, a feed pipe hydraulically connected to the radiator to provide heated water to the radiator, an inflow valve hydraulically connected to the feed pipe for adjustably restricting the flow rate of water through the radiator, an outlet pipe hydraulically connected to the radiator, so that water that flows through the radiator flows out through the outlet pipe, and a flow meter hydraulically connected to either the feed pipe or the outlet pipe to measure the flowrate of water passing though the radiator.
2. 2. A central heating system according to claim 1, wherein each radiator circuit further comprises an outflow valve hydraulically connected to the outlet pipe for adjustably restricting the flowrate of water through the radiator.
3. 3. A method for balancing the central heating system of claims 1 and 2, wherein the method includes the steps of: adjusting either the inflow valve or the outflow valve of one or more radiator circuits to adjust the flowrate of water through the associated radiator, determining the new flowrate from the associated flowmeter and comparing this flowrate to a desired nominal flow rate, and making any further adjustment necessary to the inflow valve or the outflow valve to equalise the flowrate indicated by the associated flowmeter with the desired nominal flowrate.