Central Heating And Cooling System

Abstract

A central heating and cooling system comprising two independent circuits of the singe-tube type, a cold circuit which is coupled with its outgoing and return lines to a central cold-production machine and a hot circuit, also with outgoing and return lines coupled to a boiler or boilers, or alternatively to an exchanger or exchangers. These circuits comprise as many branch conduit lines as there are levels or stages in which the utilization points are located, each utilization point comprising a water-air temperature-exchange unit having a single air circuit. Each branch line has a pump upstream of its exchanger and a nonreturn valve downstream of its exchanger, flow through the branch line being from a first point on the associated main conduit to a second point on the associated main conduit, the first point being downstream of the second point with respect to flow of the heat exchange fluid through the main conduit. In this way the flow of the fluid through the branch line is prevented when the associated pump is not in operation.

Description

In central air conditioning system, either by induction or by convector fans, the conclusion was reached several years ago that the necessary versatility can only be obtained by a possibility of supplying hot water and cold water at any period of the year.

This result is at present obtained by the method usually known as the "four-tube method," these tubes being:

Outgoing cold water,

Cold water return,

Outgoing hot water, and

Hot water return.

In these installations, numerous systems of automatic control are employed, such as six-way motor-driven or thermostatic valves, units of two valves with three or two ways, motor-driven shutters which control the passage of air through the units, etc.

The invention has for its object a simplified installation which, when applied to a central air-conditioning system, makes it possible to obtain, with a circuit arranged on a basis of two tubes, the same results as those obtained at the present time with four-tube installations.

This reduction in the number of elements has considerable advantages from the point of view of economy, not only of material, but also of specialized labor.

A simplified installation according to the invention comprises two independent circuits of the single-tube type, a cold circuit and a hot circuit. The cold-water circuit is connected to the central production machine and the hot-water circuit is connected to the boiler or boilers (or to the exchanger or exchangers) and their temperature may or may not be automatically regulated in dependence on the external temperature.

The water-air temperature exchange unit of each air inductor (convector fan) is divided into two separate circuits as regards the water, but is common with respect to the air circuit.

The circulation of the water in each part of the units is effected by means of two electric pumps of appropriate characteristics and small size, preferably incorporated inside the inductor or convector fan, but which may also be housed at a short distance outside the apparatus.

In order to prevent the water of one circuit from circulating during the stoppage of the corresponding pump, each of the circuits is provided with a non-return valve mounted in an appropriate manner.

Generally, the operation is as follows:

When it is desired to heat, hot water circulates in the corresponding part of the battery under the action of the hot-water pump which is in operation.

When it is desired to cool, cold-water circulates in the corresponding portion of the unit by the action of the cold-water pump which is in operation.

These pumps may be actuated manually or by means of electric switches, or alternatively by means of thermostatic switches (ambient temperature or return thermostat). The controls of these elements may preferably be combined in such a manner that they can only operate alternatively, the closure of one certain electric circuit necessarily involving the opening of the other, so as to prevent the possibility of simultaneous operation of the cold-water pump and the hot-water pump. It is only in installations located in very damp regions that it is possible to install in combination a thermostat and a humidostat, enabling moisture to be removed from the treated air by their simultaneous operation.

In addition to the advantages of an economic order which have been referred to previously, installations of the kind described offer the following advantages:

An economy of two conduits is made in the whole of the path of the circuit;

The versatility of the system is perfect, since the circulation of cold water and the circulation of hot water are immediate;

Since the pressure required for the pumps is reduced to the simple value of the pressure loss of the battery, the consumption of each pump is very small;

In mass production of the types of pump to be employed in this kind of installation, the production cost of the pumps is less than that of the thermostatic valves and the other presently-used automatic devices which are not useful in this case.

Forms of embodiment of the invention are described below by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a diagram of a simplified installation according to the invention;

FIGS. 2 and 3 are diagrams similar to that of FIG. 1 but which relate to two alternative forms.

According to the invention, FIG. 1 shows a simplified installation in which the conduit 1 of a closed circuit comes from and returns to the central machine source of cold (not shown), while the conduit 2, also on closed circuit, is connected to the source of heat. The two conduits have a circulation controlled respectively by means of a cold-water pump 3 and a hot-water pump 4. Each of these conduits has as many branch circuits, 1a and 2a as there are planes or stages in which the points of utilization are located, putting into communication the outgoing and return sections of these branch circuits.

Each utilization point comprises a water-air temperature exchange unit 5 which includes a single air circuit which is cooled or heated, depending on whether it operates on a cold-water circuit or on a hot-water circuit. The first circuit is supplied by the corresponding branch circuit 1a, and forces the circulation by means of a small pump 6 which causes it to pass through the unit 5 and returns it through a non-return valve 7 in counter-flow to the above-mentioned branch circuit 1a. The second circuit is supplied by the branch circuit 2a and is provided with the same elements: pump 6 and non-return valve 7.

The pumps 3 and 4 of the general installation and the pumps 6 of each utilization point each have their particular motor, following the diagram shown in FIG. 1, and, as has been previously stated, these motors can be put into service by means of independent switches or preferably by means of change-over switching devices which connect the hot-water pump while disconnecting the cold-water pump and vice-versa.

In the alternative form shown in FIG. 2, each pair of pumps 8 is actuated by a single motor 9, arranged axially between the two. In this case, it is necessary that the pumps should not be reversible or that they do mot produce the slightest displacement of water when they rotate in the direction opposite to the normal direction of operation. By reversing the direction of operation of the motor 9, the pump 8 is put into service, corresponding to the hot or cold circuit which is desired.

In the case where the installation comprises fan-convector apparatus, the two pumps 8 can be actuated by the driving motor of the two fans of the fan-convector. In this case, the change in operation is also effected by reversing the direction of working of the motor, and account must be taken of the fact that it is not a disadvantage for the heating condition that the fan or fans of the fan-convector rotate in the reverse direction, but an advantage due to the fact that, in this case, the flow-rate of the fans being reduced when they rotate in reverse, the outgoing temperature of the air is higher on the heating condition, the number of calories dissipated remaining practically constant.

In the alternative embodiment shown in FIG. 3, the water circulation at the utilization points is effected by means of a single reversible motorized pump unit set 10, in which each of the circuits (hot and cold) is interposed between two non-return valves 7, correctly situated, so that, depending on its direction of rotation, it sends the hot water to the battery 5 while at the same time stopping the circulation of cold water and conversely.

It will be noted that in all these alternative embodiments, the simplified installation depends on the type of pump which is employed and on the manner in which these pumps are actuated. The operation takes place in the same manner and the economy effected in the installation depends on the circumstances, since it especially depends on the demands of the contractor and the owner of the installation.

It will of course be understood that numerous alternatives of the forms of construction described can be introduced without departing from the scope of the invention, on condition that the essence of the invention is not modified. Thus, it is possible in particular to utilize pumps in which the speed of rotation is variable in dependence on the indications of an ambient temperature thermostat and an appropriate electronic device.

Claims

What I claim is:

1. A central heating and cooling system comprising separate heating and cooling circuits, said heating circuit including a first main conduit means connected to a central heating source for circulating a first heat-transfer fluid, said cooling circuit including a main conduit means connected to a central cooling source for circulating a second heat-transfer fluid, each of the circuits comprising a plurality of temperature exchange units, each temperature exchange unit being connected by a branch line between a first and a second point on its associated main conduit, a nonreturn valve and a pump in each of said branch lines, the flow of the heat-transfer fluid in each branch line being from said first point to said second point, said first point being downstream of said second point along the associated conduit means thereby preventing the flow of the heat-transfer fluids through the branch lines when their associated pumps are not in operation.

2. A system according to claim 1, wherein the first heat-transfer fluid is relatively hot water, and the second heat-transfer fluid is relatively cold water.

3. A system according to claim 1, wherein each temperature exchange unit of said heating circuit is grouped with one of the temperature exchange units of said cooling circuit to form a combined temperature exchange unit.

4. A system according to claim 3, wherein the pair of pumps of each combined temperature exchange unit are actuated by a single motor for alternative operation.

5. A system according to claim 3, further comprising a single reversible motorized pump unit for circulating heat-transfer fluid through the branch lines of each combined temperature exchange unit, and means responsive to delivery of the first heat-transfer fluid to a heating circuit branch line of the combined temperature exchange unit to interrupt the flow of the second heat-transfer fluid to the cooling circuit branch line of the same combined temperature exchange unit, and vice versa.