GB2451362A

GB2451362A - Temperature responsive valve

Info

Publication number: GB2451362A
Application number: GB0817108A
Authority: GB
Inventors: Kenneth Richard Rice
Original assignee: ALPHA THERM Ltd
Current assignee: ALPHA THERM Ltd
Priority date: 2005-05-13
Filing date: 2005-05-13
Publication date: 2009-01-28
Anticipated expiration: 2025-05-13
Also published as: GB0509844D0; GB2426044A; GB2451362B; GB0817108D0; GB2426044B

Abstract

A temperature responsive valve has an inlet 5 and two outlets 9, 10 and a valve member 6, 7 movable to block one or other of said outlets. The valve member has an expansion part which when heated expands against a spring 8 to cause the valve member to move to a position blocking outlet 9. When cool, the valve member blocks outlet 10. The expansion part may contain material which undergoes a transition when heated, such as wax.

Description

HEATING SYSTEM VALVE ARRANGEMENT

The invention relates to a valve arrangement for a heating system, especially a domestic mains water combined heating system including both a solar or other non-constant heating system together with a boiler operated by gas, electricity, solid fuel, oil or similar, and to the heating system itself.

Related Art Concerns about the use of non-renewable fuels have increased interest in heating systems using renewable energy sources, such as solar heating system.

One problem with the use of pure solar heating systems is that the solar power received varies widely throughout the year. To bridge periods when the stored solar energy is insufficient, a conventional heating system can be used to supplement the solar heating system.

In a conventional arrangement, a thermally insulated storage tank may be used with two heating systems attached, the two heating systems being for example a solar heating system and a conventional gas fired system. Hot water can be drawn from the tank, for example to supply taps. Each of the solar and gas-fired system can warm the tank through respective heat exchangers, which may conveniently be located outside the tank, or alternatively inside the tank. In the event that there is sufficient solar power reaching the solar heating system to maintain the tank temperature at a sufficient level, the gas-fired system is not used. If, however, the temperature in the tank drops and the water in the tank cannot be warmed sufficiently using solar energy, the conventional heating system may be used to warm the tank.

A less conventional way of combining solar energy and an oil burner is described in US 4,052,001 to Vogt. In this approach, return water from radiators can be passed through the oil burner or through a solar powered heat exchanger to warm the water before being returned to the radiators. An arrangement of thermometers and valves controlled in dependence on the temperatures recorded by the thermometers is used to select which of the heat exchanger and oil burner is used.

Another system is described in US 4 106,692. This system has a "heat bank" and a low inertia boiler. Water is drawn from the top of the heat bank and from a radiator return line and passes through the low inertia boiler, which may or not be on, before being used to heat the heat bank or passed through the radiators.

However, there remains a need for improved heating systems, especially ones able to combine solar power with other types of power.

Summary of Invention

According to the invention there is provided a heating system, including: a heat storage reservoir for water having a storage outlet and a storage inlet; a background heating system for heating the water in the storage reservoir; a supply outlet for supplying water to be used; a boiler for heating water passing through the boiler from a boiler inlet to a boiler outlet, the boiler outlet being connected to the supply outlet; and a thermally controlled valve having a valve inlet and first and second valve outlets, the inlet being connected to the storage outlet, the first valve outlet being connected to the supply outlet and the second valve outlet being connected to the boiler inlet, wherein the thermally controlled valve is switchable between a first operating mode in which water input at the valve inlet is output at the first valve outlet and a second operating mode in which water input at the valve inlet is output to the second valve outlet, the thermally controlled valve automatically switching from the first operating mode to the second operating mode when the temperature of the water in the valve falls below a predetermined temperature to supply water directly to the supply outlet when the temperature of the water in the heat storage reservoir is sufficient and otherwise to provide supply water to the supply outlet through the boiler.

The invention delivers a number of benefits. Firstly, the reduced requirement for gas leads to reduced carbon dioxide emissions as well as reduced running costs.

Further, the reduced heating load on the boiler reduces wear and tear on the boiler.

Moreover, the flow rate at which hot water can be delivered at any given temperature is increased, since the boiler heats water from the storage tank which is at a higher temperature than water taken directly from the mains.

The background heating system may be a solar powered system.

The system may include a heat exchanger for exchanging heal between the background healing system and the heat storage reservoir.

The boiler may an instantaneous water heating type such as a combination boiler or water heater.

The boiler may have a variable fuel flow rate, and the heating system may include a temperature sensor for sensing the temperature of the water entering the boiler, which can be used to adjust the fuel flow rate to reduce the fuel flow rate the higher the temperature of the water entering the boiler.

The thermally controlled valve may be in the form of: a valve body defining a bore therein having a central chamber; first and second valve outlets at opposed ends of the bore in water connection with opposed ends of the chamber; a valve inlet in water connection with the central chamber; and a moveable valve member in the chamber moveabic between a first position in which the valve member blocks the first valve outlet to allow water to flow from the inlet to the second valve outlet in the second operating mode and a second position in which the valve member blocks the second valve outlet to allow water to flow from the inlet to the first valve outlet in the first operating mode; wherein the moveable valve member is resiliently biased towards the first position.

The valve member may include an expansion part of thermally expanding resin having a distal end extending towards the first valve outlet and engaging with an engagement part fixed with respect to the valve body, so that when the thermally expanding resin heats above a predetermined temperature the expansion part expands against the resilient bias to move the valve member from the first towards the second position.

In another aspect the invention relates to a thermally controlled valve having first and second operating modes, comprising: a valve body defining a bore therein having a central chamber; first and second valve outlets at opposed ends of the bore in water connection with opposed ends of the chamber; a valve inlet in water connection with the central chamber; and a moveable valve member in the chamber movcablc between a first position in which the valve member blocks the first valve outlet to allow water to flow from the inlet to the second valve outlet in the second operating mode and a second position in which the valve member blocks the second valve outlet to allow water to flow from the inlet to the first valve outlet in the first operating mode; wherein the moveable valve member is resiliently biased towards the first position; and wherein the valve member includes an expansion part having a distal end extending towards the first valve outlet and engaging with an engagement part fixed with respect to the valve body, so that when the expansion part heats above a predetermined temperature the expansion part expands against the resilient bias to move the valve member from the first towards the second position.

Such a valve can reliably direct water flow from the inlet to either of the outlets depending on the temperature of the water.

In a particular embodiment, the movcab!c valve member has tapered sealing surfaces on opposed first and second ends for sealing against the inside of the chamber; the expansion part extends longitudinally from the chamber along the bore within the bore towards the first valve outlet; and the engagement part is fixed adlacent to the first valve outlet.

The resilient bias may be provided by a spring arranged between the moveable valve member and the end of the bore adjacent to the second valve outlet, the spring being arranged in compression to bias the moveable valve member towards the first position.

Brief description of the drawings

For a better understanding of the invention embodiments will now be described, purely by way of example, with reference to the accompanying drawings in which: Figure 1 shows a schematic of an embodiment of a system according to the invention operating in a first mode; Figure 2 shows a schematic of the embodiment operating in a second mode; Figure 3 shows a detail schematic of the embodiment showing the thermal valve in section in the first mode; and Figure 4 shows a detail schematic of the embodiment showing the thermal valve in section in the second mode.

Detailed Description

Referring to Figures 1 and 2, a heating system uses water as the water throughout. The system includes a solar panel I, a heat exchanger 13 and a one-way valve 14. An insulated storage tank 3 is connected to heat exchanger 13 through one-way valve 2. In use, water flows in the loop of the solar panel I, heat exchanger 13 and circulating pump 14. The water is heated by the sun in the solar panel I and the heat is transferred to water flowing in the loop of the storage tank 3, circulating pump 2 and heat exchanger 13. These components accordingly make up a background heating system.

In this way, the solar panel I heats up water in the storage tank 3 to a temperature that will depend on the amount of sunlight radiating onto the solar panel 1.

The storage tank 3 has a water inlet 4 and outlet 5 which will be referred to as the storage inlet 4 and storage outlet 5 to distinguish from other inlets and outlets in the system. The storage inlet 4 is connected to the domestic mains water supply.

The outlet 5 of the storage tank 3 is connected to valve inlet 22 of thermal valve 6 which in the arrangement shown in Figure 1 operates in a first mode passing the water to the first outlet 20 of the thermal valve. The thermal valve has a second valve outlet 21, and in a second mode, as illustrated in Figure 2, water is passed from the valve inlet 22 to the second valve outlet 21.

The thermal valve switches at a predetermined water temperature between the first and second modes; above this temperature the valve operates in the first mode and below this temperature the valve operates in the second mode. For example, the predetermined temperature may be in the range 40 oC to 70 °C, preferably 45 °C to 55 °C. The valve 6 operates quickly and moves between the first and second modes in a few seconds.

The operation of the thermal valve 6 will be described in more detail below.

A boiler 7 is connected to the second valve outlet 21 -in the embodiment this is a gas conibi-boiler but it could also be any instananeous water heater with temperature control.

The boiler includes a primary heat exchanger 11, a secondary heat exchanger 10, a circulating pump 39 (Fig. 3) and a burner 12. Water is circulated in a closed loop via the circulating pump 39, to the primary heat exchanger 1 1 where it is heated by the burner 12 and then it flows to the secondary heat exchanger 10. The heat is then transferred via the secondary heat exchanger 10 to the mains water enetering at the boiler inlet 18 and leaving at the boiler outlet 19.

The boiler outlet 19 and first valve outlet 20 are connected to supply outlet 8, here a hot water tap arranged to supply water for a bath 9. The skilled person will realise that there are many other supply outlets possible, including other hot water taps.

Figure 1 shows a number of components, including a temperature sensor IS to measure the temperature of water leaving the boiler 7. Fuel enters the boiler from fuel supply 17 through controllable valve 16 to burner 12. A controller 30 controls valve 16 to adjust the fuel flow to burner 12 depending on the outlet temperature. These components may conveniently be integrated in the boiler and in a preferred embodiment the boiler includes these components.

In use, as long as the temperature of water in the storage tank 3 remains above the predetermined temperature, the thermal valve 6 operates in the first mode and water is supplied to supply outlet 8 without passing through boiler 7.

If the temperature falls below the predetermined temperature, which may be for example 48 °C, the valve 6 switches to its second operating mode in which water is passed through boiler 7 which heats it to another desired temperature, for example 55 °C, and supplies it to supply outlet 8.

Note that the system does not attempt to maintain the temperature of water in storage IS tank 3 at any predetermined temperature, unlike conventional prior art systems or a system according to US 4,106,692. Accordingly, water is stored in tank 3 only if there is sufficient solar energy to warm the water. If not, fuel from the burner is not used to maintain this temperature.

By passing the water from the storage tank 3 to outlet 8 through boiler 7 even when the water temperature in tank 3 is too low to be supplied directly to outlet 8, the amount of heating required in boiler 7 is reduced in the normal case where some solar power is available to warm the water in the tank 3 above that of the mains supplied at inlet 4.

This is to be compared with the prior arrangement of US 4,052,001 which does not deliver this benefit.

Further, note that the arrangement of US 4,052,00] requires a relatively complex control arrangement of valves and thermometers, whereas the present invention requires nothing more complex than valve 6 and can operate without any electrical control to operate this valve at all.

Also, note that the temperature at which valve 6 swtiches is a little lower than that normally used for hot water systems, in this embodiment, which reduces the need for the boiler to be operated in marginal conditions.

Figures 3 and 4 illustrate the valve 6 in more detail.

The valve has valve body 23 defining a central valve chamber 24 and a longitudinal bore 27 passing through the body 23. A first end member 25 closes one end of bore 27, the first end member defining first valve outlet 20 within it. A second end member 26 closes the other end of the bore 27; it is arranged adjacent to second valve outlet 21.

The first and second end members 25, 26 screw into valve body 23.

An engagement part 28 is formed at the centre of the bore 27 as an integral part of first end member 25.

An expansion member 3 I is located within the bore 27 and chamber 24. It has a central part 32 within chamber 24 and a longitudinally extending nose 38 extending from the central part 32 within the bore 27 to engage with engagement part 28.

In a preferred embodiment, the longitudinally extending nose 38 is a separately formed element able to move with respect to the central part 32, the central part containing a thermally responsive material. The material may be for example wax that melts at the predetermined temperature and accordingly that expands and contracts with changes in temperature and as a result moves the nose 38 in and out with respect to central part 32.

The central part 32 has first 33 and second 34 tapered sealing surfaces on opposed longitudinal ends shaped to engage with tapered first 35 and second 36 valve seats in chamber 24.

Spring 37 is arranged in compression between the second end member 26 and the central part 32 of the expansion member 31, and resiliently biases the expansion member towards the first valve outlet 20.

When the expansion member 3 1 is cool, the expansion member is in a first position as shown in Figure 4, in which the spring 37 biases the first sealing surface 33 of the expansion member againts the tapered first valve seat 35 to seal off the first valve outlet in a second operating mode.

As the water passing through the valve heats the expansion member 3 1, the expansion member 3 1 and especially the nose 38 expands, urging the expansion member against the action of the resilient bias spring 37 to the first operating mode shown in Figure 3 with the second tapered sealing surface 34 sealing against the second valve seat 36 to block the second valve outlet 21 and allow water to flow from inlet 22 to first valve outlet 20.

Note that the tapered sealing surfaces and valve seats allow the expansion member to be self-centring in the bore 27.

The invention is not restricted to the embodiment described above.

For example, the background heating system need not be solar, but any other heating system that may be intermittent can be used. For example, the system might be a heat pump system or heat from a combined heat and power system.

Claims

I. A thermally controlled valve having first and second operating modes, comprising: a valve body defining a bore therein having a central chamber; first and second valve outlets at opposed ends of the bore in water connection with opposed ends of the chamber; a valve inlet in water connection with the central chamber; and a moveable valve member in the chamber moveable between a first position in which the valve member blocks the first valve outlet to allow water to flow from the inlet to the second valve outlet in the second operating mode and a second position in which the valve member blocks the second valve outlet to allow water to flow from the inlet to the first valve outlet in the first operating mode; wherein the moveable valve member is resiliently biased towards the first position; and wherein the valve member includes an expansion part engaging with an engagement part fixed with respect to the valve body, so that when the expansion part heats above a predetermined temperature the expansion part expands against the resilient bias to move the valve member from the first towards the second position.
2. A valve according to claim I wherein the moveable valve member includes a central part in the form of a hollow housing containing a material that undergoes a transition at the predetermined temperature, wherein the expansion part is a separate compenent moveable with respect to the central part that is moved when the material undergoes a transition at the predetermined temperature to extend or contract the expansion part.
3. A valve according to claim 1 or 2 wherein the chamber has first and second valve seats at the ends of the chamber around the bore leading to the first and second valve outlets respectively; the moveable valve member has tapered sealing surfaces on opposed first and second ends for sealing against the valve seats; the expansion part extends longitudinally from the chamber along the bore within the bore towards the first valve outlet; and the engagement part is fixed adjacent to the first valve outlet.
4. A valve according to claim I.2 or 3 further comprising a spring arranged between the movcable valve member and the end of the bore adjacent to the second valve outlet, the spring being arranged in compression to bias the moveable valve member towards the first position.