GB2446602A

GB2446602A - Thermal regulation of water

Info

Publication number: GB2446602A
Application number: GB0702731A
Authority: GB
Inventors: Menachem Porat
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-02-13
Filing date: 2007-02-13
Publication date: 2008-08-20
Also published as: GB0702731D0

Abstract

A system for warming water in a water conduit for use by a consumer, comprises a heated water reservoir 24, a conduit 26 for conducting water from the reservoir to a water outlet and a faucet 44 for allowing water to flow out of the system. A conduit heater 28 capable of heating a segment of the conduit is provided. The system further includes a temperature sensor associated with water at the outlet of the conduit, a signal conditioner 48 for conditioning a signal from the temperature sensor, a processor 38 for storing at least one reading of the temperature sensor and for performing calculations on at least two readings and a memory associated with the processor. When the faucet opens, the water heating segment of the conduit starts warming the water only when temperature of the water coming from the reservoir rises. Preferably the water reservoir is heated by solar power and the conduit heater is heated by electric, gas or kerosene.

Description

1 2446602

THERMAL REGULATION FOR HOT WATER UPON DEMAND

FIELD OF ThE INVENTION

The present invention is in the field of control systems for water temperature and more specifically in the field of home water temperature control.

BACKGROUND OF THE INVENTION

Water available for personal use in the home or workplace such as for washing or cooking is oftentimes colder than would have been convenient for the user. Electzical, solar or fuel based warming systems are available in the market for raising the temperature to an acceptable level, at the cost of installation, maintenance and energy expenditure. Warming system usually include a larger hot water reservoir, referred to as boiler sometimes, a heating unit and sometimes also a smaller conduit healing unit which heats water just as it comes out of the tap, employing no additional reservoir. Systems for healing water for personal use are known in the art, such as the one disclosed in US Patent 644588O BI, which is concerned with providing a flow of constant temperature stream of water.

It Is the aim of the present invention to provide a system and a method for reducing the cost of energy spent to provide conveniently warm water for the personal use.

BRIEF DESCRIPTION OF ThE DRAWINGS

Fig. I is a block diagram descilbing the topology of the components of the system in which the invention is implemented and their interaction.

Fig. 2 is a diagram dosctibing the sequence of steps implemented in process for heating water at a conduit, in accordance with the invention.

DETAILED DESCRIP11ON OF THE PRESENT INVENTION The system of the present invention aims to produce water to be consumed by a user, by applying heating in accordance with a scheme implemented by the system. To explain the system components, topology, component interaction and regulation procedure, reference is first made to Fig. 1. Water conducted from a heated water reservoir (HWR) 24 flows in a conduit to subsequently reach a specific segment, proximal to the pounng end of the conduit, hereinafter referred to as heatable conduit 26. Conduit heater 28 is fed by energy supplied by energy supply means 30. Energy Is sent from the energy supply means to be fed into the target conduit heating means under the supervision of processor 38. Water outlet 44 is a spout or tap through which the heated water Is poured to be used by a user. In association with water outlet 44 is disposed temperature sensor 46, as known in the art, that can send signals the magnitude of which relate to the temperature in the outlet, to processor 38.

Typically, however, the signal is conditioned prior to processing by one or more signal conditioners 48, for example by amplification and conversion to digital form. A note is made that in association with the processor of any embodiment of the invention there is provided an electronic memory system that can store at least one temperature reading but preferably more than two. The processor in the sense of the present invention also handles the memory directly or indirectly as known in the art. The conduit heater referred to in the present description relates to any heater which heats the water conduit without storing the water subjected to heating in a tank. Such heaters are sometimes referred to as tank-less heaters.

In a preferred embodiment of the invention, the heated water reservoir, is a solar water heating tank for home use. Energy for heating a heatable conduit Is for example electric, gas or kerosene burning. The temperature sensor is typically a thermocouple or a thermistor that feeds signals to a signal conditioner including usually amplifier, filter and AID converter for conveying the signal to a processor. The processor implements a procedure as follows: Procedure for heating water for home use In accordance with the present invention, water coming out of the water outlet is subjected to heating by the conduit heater only when a sequence of several conditional requirements is met. The procedure for initializing activation and for keeping the temperature at a substantially steady temperature, i 5 IS described In the flow chart of FIg. 2, to which reference is now made. The heating procedure begins in step 152 following an instruction by the user to start, such as by opening a faucet, in which the temperature at the water outlet is read by the sensor disposed in association with the water at the outlet. Typically, the temperature is read every 10 seconds. Then, at step 154 the last temperature values, at least a sequence of two, is stored in the processor. Then, at step 156 a decision is made. If the temperature trend is to increase, by a certain predefined threshold, IRI the system will apply heat at step 158, a prior art system may be employed to keep the temperature substantially constant. The temperature at the outlet is measured with some intervals as described above, If the temperature at the outlet rises above a predelined threshold level TUT a decision is made at step 162 to stop the heating at step 164. Nonetheless the system also checks for a decrease in temperature, at step 166. If the temperature drops such as by exhibiting a threshold tendency of change T, the system would cease heating.

The tendency for temperature change is calculated by the processor by comparing two or more consecutive temperature measurements. To implement this, the system must be able to store at least one temperature. If only one temperature reading is taken, the current temperature reading is used in addition to the stored reading. However, preferably more than one temperature readings are stored typically in order to perform more elaborate calculations regarding temperature change tendency.

The three temperature thresholds Threshold TRI is, as explained above, a predetermined certain minimum temperature or temperature change which signifies a certain predefined trend of temperature rise, for example, an increase of 0.5 C over two or three consecutive readings. The dedsion that the system makes to start the heating takes place only when the temperature exhibits a predeflned tendency as defined by the processor. (0

Threshold TUT is a temperature value which determines a maximal temperature which is considered allowable for use by the user. If the temperature at the outlet reaches this high, heating will stop.

The third threshold is Tp which is the threshold tendency of the temperature to change after the conduit heater stopped operating by the user or a hot water faucet conducting hot water to the water outlet has been turned off or for any reason whatsoever. This tendency is measured by comparing the values of consecutive readings of the temperature at the outlet. For example, If over two or six consecutive readings the temperature decrease steadily by 1.0 C the heating will stop.

Advantages of the usage of the system and of the procedure of the Invention A common situation is one in which water from a water tank, such as an solar heater, is used for showering in the home bathroom. Typically, the water in the heater tank is stored over periods of hours before use. In periods in which the solar energy is not readily available or not available at all, such as in the night or in cloudy periods, the temperature of the stored water is lower than optimal for use by the person using the water. The conduits on the way from the boiler to the outlet may be cold because of their relatively large surface area, or because

I

of cooling brought about by cold conducted water. When the user opens the faucet, a stream of water colder than optimal is let out.

Until such time as the warm water from the boiler or solar heart tank reaches the outlet and after warming the conduit along their path, a conduit heater can be activated as dIscussed above. Any other mechanism whIch may cause a delay counting from the start of water flow to the activation of the conduit heater. In accordance with the present invention, the conduit heater is activated when the water temperature at the outlet starts to warm. This way the conduit heater draws energy to bridge a diminishing temperature gap between the reservoir water temperature and the measured temperature at the outlet.

The active heating by the conduit heater stops when either of two scenarios occur. Thus, if the measured temperature in the water outlet is higher than the predefined acceptable, at threshold temperature TUT, heating stops. In another scenario, when the user turns off the hot water faucet, and the temperature at the outlet decreases steadily, the system calculates a temperature change tendency, and if the cooling passes a certain threshold Tp,, heating will stop.

In a different embodiment of the present invention, two heat sensors are used instead of one. One sensor is disposed upstream before the conduit heater and one disposed downstream after the conduit heater. In such case, the temperature of both sensors is compared and if the temperature at the sensor disposed before the conduit heater indicates a lower temperature than the temperature at the other sensor, by a threshold by a predetermined difference, heating is not facilitated. In this embodiment, the use of a processor may not be required, and the determination of difference in temperatures may be accomplished by a comparator measuring the output of the sensors.

Benefits of Implementing the Invention The present invention implements an energy saving strategy that dictates energy expenditure for heating of water in demand only when the stream from the heated water tank indicates heated water is supplied. This strategy insures that water reaching from a tank or reservoir is heated when temperatures are already on the rise, saving energy spent on heating colder water. In a similar fashion, if the water cools down after the heating has been affected, the system will stop heating.

Claims

A system for warming water in a water conduit useful in the production of a quantity of water to be consumed by a user, said system comprising: * a heated water reservoir; * a conduit for conducting water from said reservoir to a water outlet: * a faucet for allowing water to flow out of said system for the benefit of a user; * a temperature sensor in association with water at said outlet; * a signal conditioner for conditioning the signal of said temperature sensor; * a processor for storing at least one reading of said temperature sensor and for performing calculations on said at least two readings; * a memory associated with said processor; * a conduit heater capable of heating a segment of said conduit, and * a water faucet for shutting off water to said water outlet.
2. A system for warming water as in claim I wherein said faucet is a hot water faucet.
3. A method for heating water flowing in a conduit for personal use, said method comprising: * successively measuring temperature of the water in a water outlet of said conduit; * calculating the of temperature change tendency in said water; * conditionally turning on a conduit heating means proximal to the pouring end of said conduit, when said tendency is a warming tendency.
4. A method for heating water flowing in a conduit for personal use as in claim 3, wherein said conduit heating is turned off when said tendency is a cooling tendency.