Heating systems – Water – Expansion tanks
Patent
1989-01-04
1991-04-16
Bennet, Henry A.
Heating systems
Water
Expansion tanks
237 59, F24D 310
Patent
active
050075837
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a device for accommodating expansion absorption in fluid circulation systems, in particular of heating or cooling installations, having at least one expansion vessel preferably in gas exchange with the atmosphere, into which liquid from the fluid circulation system is received and from which liquid is returned to the fluid circulation system via a pressure pump. An overflow valve which is adjustable to the operating pressure of the installation is provided in one conduit of the expansion vessel, so that a lower pressure prevails in the expansion vessel than in the fluid circulation system.
It is known that in heating installations, due to the heating or cooling of the heating fluid (water), a volume change occurs. Upon heating, the additional volume must be taken out of the fluid circulation, and upon cooling, returned into the fluid circulation again. In such heating installations it is known practice to transfer the excess heating fluid resulting from the thermal expansion into an open expansion vessel and upon cooling to supply heating fluid to the fluid circulation again via a pump.
Further also closed expansion vessels are known for this purpose. In this connection it is current practice to open a solenoid valve when a certain positive pressure is reached in the fluid circulation and to transfer the heating fluid from the circulation into the expansion vessel. When the pressure drops in the installation, the forcing pump is turned on and heating fluid is pumped from the expansion vessel into the fluid circulation. An example of such an installation can be seen in German patent document DE-A1-2,516,424. By this intermittent removal from and return of heating fluid into the fluid circulation considerable pressure fluctuations occur in the installation. Similar conditions appear also in cooling installations.
SUMMARY OF THE INVENTION
It is, therefore, the object of the invention to improve a device of the initially mentioned kind to the effect that the pressure compensation occurs smoothly and practically without pressure fluctuations in the fluid circulation system.
According to the invention, this is achieved in that the expansion vessel is connected to the fluid circulation system via separate inflow and outflow conduits and that in the outflow conduit from the expansion vessel a continuously running forcing and circulating pump is arranged.
The forcing and circulating pump continuously conveys liquid from the expansion vessel into the circulation system and, if correctly dimensioned, provides for maintaining the operating pressure in the circulation system to which the overflow valve in the inflow conduit to the expansion vessel is adjusted. Under normal operation at least a partial stream of the circulation fluid flows continuously through the overflow valve or through the expansion vessel. During the heating phase of the circulation fluid temporarily more fluid passes through the overflow valve into the expansion vessel than is conveyed from the latter by the forcing and circulating pump. This causes the liquid level in the expansion vessel to rise. In the cooling phase of the circulation fluid, conversely, more liquid is conveyed from the expansion vessel into the circulation system than flows into the expansion vessel via the overflow valve. The liquid level in the expansion vessel falls again. All this takes place practically without fluctuations of the operating pressure in the circulation system. The quantity of water delivered by the pump determines the flow through the valve. The pressure circulation need not be monitored.
In the device according to the invention a complex control technology for the control and monitoring of the installation can be dispensed with, and also there will be no wear and noise as is the case with the relatively frequent switching of solenoid valves and pumps operating intermittently.
It is possible to conduct only a partial stream of the system fluid (heating fluid) via the expansion vessel or, in
REFERENCES:
patent: 4013221 (1977-03-01), Eder
A. Schwarz & Co.
Bennet Henry A.
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