Heating systems – Automatic control – Water
Patent
1996-07-23
1998-02-17
Joyce, Harold
Heating systems
Automatic control
Water
237 56, F24D 300
Patent
active
057183740
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a heating installation of the type which operates with a closed liquid circuit which is under pressure during operation. Incorporated on the one hand in the liquid circuit is a heating boiler in which heat is supplied to the liquid circulating in the circuit. Incorporated on the other hand in the liquid circuit are radiators and/or convectors by means of which heat is generated from the liquid to spaces for heating. Instead of or in addition to convectors and radiators an air transporting system can be used.
Heating installation of this type normally comprise a pressure expansion tank. Accommodated herein is the extra volume of liquid resulting from expansion as a result of heating of the liquid. When the liquid in the liquid circuit cools, liquid is carried from the pressure tank back into the circuit again to compensate the volume decrease due to this cooling.
Due to very small leakages in the system some loss of liquid occurs in the course of time. Through decomposition resulting from electrolysis or bacteriological action and through evaporation a part of the liquid also passes into a gaseous phase which is discharged from the system. The amount of liquid in the system thereby decreases gradually during normal use. The lost liquid must therefore be supplemented periodically. This is a time-consuming operation wherein a temporary connection to for instance the mains water supply is effected and, using the pressure in the mains water supply, water is pressed into the liquid circuit.
In addition, the known pressure tanks have a limited lifespan.
The invention has for its object to provide a heating installation of the type specified in the preamble which requires little maintenance and attention over a long period.
This object is achieved with the heating installation comprising a closed liquid circuit which is under pressure during operation, a pressureless liquid reservoir, an actuable pump with an inlet connected to the reservoir and an outlet connected to the circuit, an actuable drain to drain liquid out of the circuit to the reservoir, a pressure detector to detect the pressure in the circuit, a control to activate the pump when exceeding of a minimum pressure in a negative direction is detected and for activating the drain when exceeding of a maximum pressure in a positive direction is detected. Through use of a pressureless liquid reservoir with an actuable pump and actuable draining means, a number of advantages are achieved in a closed liquid circuit which is under pressure during operation. The pressure in the liquid circuit can be held constant within very narrow limits, for instance 0.2 bar. The boiler, radiators and the like therefore require a less heavy construction since no great pressure variations have to be absorbed.
The liquid which enters the liquid reservoir undergoes a fall in pressure, whereby any gases which may be dissolved in the liquid are easily released. This is because the saturation level for gases absorbed into the liquid decreases together with the pressure. The liquid carried out of the circuit to the liquid reservoir is thus degassed to the degree of saturation associated with the lower atmospheric pressure. When this thus degassed liquid is returned to the liquid circuit where the pressure is higher this liquid is unsaturated. Gas occurring freely in the circuit consequently dissolves in the liquid and is eventually discharged again into the reservoir. Because during heating and cooling of the installation liquid is transported in each case to and fro to the reservoir and back, the liquid in the circuit will be quickly degassed and accumulations of gas in the circuit itself will be avoided almost entirely. Oxygen absorbed into the liquid is very quickly removed therefrom so that internal oxidation and bacteria growth in the system are avoided. In the case of a just filled system the liquid can be degassed very rapidly by varying within permissible limits the minimum and maximum pressure detected with the control means. If use is made of a comp
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Boles Derek S.
Joyce Harold
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