GB2512584A - Water storage for heating systems - Google Patents

Abstract

A hot water storage container 1 for incorporation into a combined heating and hot water circuit has a heat exchanger 7 for hot tap-water inside it, the outlet from which spits two ways, one way to the points of use 10 and the other to a valve 11 which opens in response to overheating conditions affecting the sensor 12 and so allows the container to be cooled by passing water through the heat exchanger. At the lower part of the container are two ducts 5 and 6 above which a shelf 14 extends and which serves to restrict convection from the two ducts and promote transfer of water between them, this reduces the effect of cold water from the two ducts adversely effecting the heating system.

Description

TITLE: Water Storage for Heating Systems

BACKGROUND:

Where a boiler is used to heat water for circulation into a domestic circuit of heat emitters such as radiators combined with provision for domestic hot tap water it is customary to store a quantity of hot watcr in a storagc containcr, commonly a cylindcr. This storc of watcr can scrvc as a buffcr to takc up surpluscs of hcat production and to supply short pcriods of hcat shortage, and, by allowing stored heat to build up over time, provide for the rapid supply of hot water to taps which would otherwise require a heat source -a boiler -of inordinately high power.

Onc way of supplying clcan, frcsh hot watcr to taps from such a hcat storc is to havc a hcat cxchangcr insidc thc storagc containcr and immcrscd in thc hot watcr. Cold watcr from thc supply mains is passed through the heat exchanger and emerges hot to the domestic taps.

There are known problems with this type of heat store, one of which involves it becoming too hot, the other involves it being too cool, each of which is addressed by aspects of this invcntion.

The too hot' problem is when the whole store builds up heat to the point where it may boil, damaging components, risking explosion and emitting dangerous scalding steam or water.

This is a particular risk whcrc biomass or othcr solid fucl boilcrs arc uscd as such hcat sourccs are not instantly responsive to control and may, or generally do, continue to produce significant hcat cvcn aftcr control systcms may havc shut thcm down. This boiling risk is commonly allcviatcd by having a sccond hcat cxchangcr insidc, or against, thc watcr storc, or against or inside the boiler, through which cold water from storage can be passed if a detector identifies overheating. This cold water cools down the store and is then emitted to waste. But this requires an extra heat exchanger, which is expensive.

Thc too cold' problcm occurs bccausc thc hcat storc is vcry big and takcs a long timc to warm up, so that for a significant pcriod aftcr a boilcr or othcr hcat sourcc is initiatcd rclativcly cold water is being retumed to the boiler, which causes condensation inside the boiler which leads to corrosion, as well as poor seivice to the householder who must needs wait for the whole, often very large, heat store to warm before heat is available to the building. This problem is oftcn addrcsscd by ihc usc oVa systcm orvalvcs and divcrtcrs which makc sum that only hol water circulates round the boiler and is only allowed into the store when it is hot, but such a system often relies on complex valves and does not always fully address the problem of slow starting heat-up.

Thc prcscnt invcntion providcs ways of solving both thc too hot' and thc too cold' problcms without the need for additional heat exchangers or a significant number of valves or any clcctrical dcviccs.

KNOWN PRIOR ART

1.SYSTEM FOR PRODUCING HOT WATER USING WATER-FILLED SOLAR THERMAL COLLECTORS, IN WHICH A SINGLE CIRCUIT CONNECTS A HOT WATER TANK AND THE COLLECTORS, INCLUDING AN

OVERHEAT PROTECTION DEVICE CPC:

Inventor: Applicant: F24D11/00 I PC: THOMERE THOMERE FINANCE 3 Publication info: Priority F24D1 1/00 YANNICK [FR] [FR] F24D19/l0 W02013011039 (Al) date: F24D19/10 THOMERE THOMEREYANNICK 42 2013-01-24 2011-07-19 F24J2/46 FREDERIC [FR] [FR] (-1) F24J2/4621 (±1) 2. A BOILER OVER-HEATING PREVENTION CONTROL METHOD Inventor: KIM KYEONG IPC: Publication info: Priority Applicant: CPC: F24D19/10 KR20120006681 (A) date: SEOB [KR] RANEE CORP [KR] KIM BYOUNG F24D3/02 2012-01-19 2010-07-13 SEOK [KR] 3. Anti-overheating device and water heater with same Inventor: Applicant: IPC: Publication info: Priority

JINBIAO LI BEIJING SOLAR

CPC: F24J2/46 CN102338491 (A) date:

LIANKUI GAO ENERGY RES INST CO

H01H37152 2012-02-01 2010-07-27 (+2) LTD 4. Solar phase-change heat accumulation water heater with overheating protection device IPC: Publication info: Applicant: F24J2105 CN101846399 (A) Priority Inventor: SHANGHAI GENERAL CPC: F24J2124 2010-09-29 date: SHUQIANG SU ENERGY YO2E1O/44 F24J2/34 CN101846399 (B) 2009-03-27

TECHNOLOGY CO LTD

(-2) 2013-02-27

DISCLOSURE:

The invention is a hot-water storage container for use as part of a combined heating and hot-water circuit.

An embodiment of the invention is here disclosed in figures 1 and 2, where figure 1 is a schematic cross-section and figure 2 represents a perspective view of one possible practical construction shown assembled as if ready for use, with a part of the outer shell of the container shown as if cut away to display the interior. A further figure 3 shows, diagrammatically, how the invention may be incorporated into a heating system. Figure 3 is not part of the invention and is included for information only.

In both figures 1 and 2, 1 is the outer shell of the water container, 2 is the body of water in the container, 3 is an inlet whereby hot water from a water heater, such as a boiler', can enter the container and mix with the main body of water 4 is an outlet of hot water to a heating circuit, is an inlet of cooler water returning from a heating circuit, 6 is an outlet of cooler water to a water heater, such as a boiler, to be re-heated, 7 is a heat exchanger between the stored hot water at (2) and cold water arriving at (8). In these diagrams the heat exchanger is shown as a convolute tube, but it may take other forms 9 is the passage through which water heated by passing through the heat exchanger (7) is discharged, indicates the route by which water heated by passing through the heat exchanger goes to the water taps, II is a valve, operated in response to a sensor (12) responsive to the temperature in a high part so that the valve can open and allow the discharge of water through the heat exchangcr and out at (13), 14 is a baffle consisting of a plate located above the inside terminii of the lower water connections (5) and (6).

The operation of the invention is as follows: Hot water from a source such as a boiler' arrives at the upper inlet (3) of the water container (1), displacing some of the contents (2) through a lower outlet (6) to be returned to the boiler' for re-heating. The body of water (2) becomes hot. A heat exchanger (7) immersed in the body of water (2) has an inlet (8) connected directly to a source of fresh water under and an outlet (9) which can be connected to taps or other water-using devices. If a tap or device is opened, water can pass through the heat exchanger, collecting heat from the body of water (2) and emerge as a hot water stream. A sensor (12) is located near the hottest part of the body of water (2). Should the sensor (12) detect that the body of water is so hot as to risk boiling it causes the valve (11) to open and so allow a stream of water to enter the heat exchanger, absorb heat from the main body and be discharged through the exit pipe at (9). In this way dangerous heating is prevented without the need for a separate cooling device by using the cooling ability of the hot-tap-water heat exchanger. In essence this feature of the invention does just what householders have done for more than a century -if their hot water storage cylinder is boiling, they have opened a domestic water tap to run hot water off to waste. The invention opens a dedicated tap' in an automatic and controlled way.

At the lower part of the storage container (1) are two ducts (5) and (6) communicating the body of water (2) to the outside. Directly above the inside opening of these ducts is a surface extending from the inside of the wall (1) of the storage container part of the distance towards the opposite wall of the storage container so as to form a shelf or hood above the opening of both the ducts (5) and (6). This shelf or baffle frrnctions to impede the natural circulation of water by convection from the ducts so that, if there is an artificially induced pressure difference between the water in duct (5) and duct (6) then water will be drawn from one of those ducts to the other in preference to circulating into the main body of water (2). This helps ensure that, during a heat-up phase, the passage of very cold water from the central heating circuit into the boiler circuit is minimised.