GB2034878A - Fan-assisted storage heater - Google Patents

Abstract

A fan-assisted storage heater has two stacks 1, 2 of thermal storage blocks with a gap 4 therebetween. The gap 4 is closed at the top and sides and is divided into a central and two side channels by baffles 5 which allow air to be blown by the fan 7 up the central channel and down the side channels. On emerging from the bottom of the side channels the hot air is mixed with cool ambient air and is directed up within the heater cabinet 9 to emerge from the top 12. <IMAGE>

Description

SPECIFICATION Fan assisted storage heater The invention relates to a storage heater having a fan to assist in removing heat by forced draught.

A storage heater generally comprises a stack of thermal blocks -- typically of concrete -- with an electric heating element running through them.

Cheap rate electricity at night is used to heat the blocks and they heat the air during the day, Such a heater can become extremely hot inside. In order to remove the heat efficiently it has been proposed to provide a duct within the blocks and to blow air through the duct by means of a fan. Such arrangements have been found to be impracticable because the temperature of the emerging air is dangerously high. The present invention seeks to provide an improved fanassisted storage heater.

According to the invention there is provided a storage heater comprising: two stacks of thermal blocks facing each other with an air-gap therebetween; thermal insulation surrounding the pair of stacks and blocking the air-gap at the top and sides; two baffles extending vertically from the bottom to near the top of the air-gap, so dividing the airgap into a central channel and two side channels; a blower fan at the base of the central channel; and a cabinet enclosing the stacks and the fan and defining an air space around the insulation, the cabinet having inlet vents at the bottom and outlet vents at the top, the arrangement being such that air is drawn in by the fan, is blown up the central channel, is directed down the side channels, mixes with cool ambient air at the base of the cabinet and rises in the air space to emerge from the top.

With this arrangement efficient heat transfer is possible and the hot air mixes with cool air to emerge at a satisfactory temperature.

Preferably the fan has by-pass outlets to the base of each side channel to enhance mixing of the hot air with cool air.

The invention will further be described with reference to the accompanying drawings, of which: Figure 1 is a cross-sectional front elevation; Figure 2 is a view from beneath the heater of Figure 1; Figure 3 is a cross-sectional side elevation taken at 'A-A' in Figure 1; and Figure 4 is a cross-sectional side elevation taken at 'B-B' of Figure 1.

Referring to the drawings the heater comprises two stacks 1 and 2 of thermal blocks of concrete.

Electric heating elements 3 run through the blocks. The stacks are spaced apart to define a vertical air-gap 4. Two vertical baffles 5 divide the air-gap into a central channel 4a and two side channels 4b and 4c.

A layer of thermal insulation 6 encloses the stacks and blocks the top and sides of the air-gap.

A centrifugal fan 7 is driven by an electric motor 8 and is mounted at the base of the central channel 4a. A cabinet 9 encloses the thermal blocks and fan and defines an air space 10 around the insulation. Inlet vents 11 are provided at the base of the cabinet and outlet vents 1 2 at the top.

In operation, the blocks are heated during the night and in the morning the fan is started. l his draws air in through vents 11 and directs the air up the channel 4a and down channels 4b and 4c.

The air is heated in the air-gap and the hot air mixes with cool air admitted in to the vents 11.

The mixing effect is enhanced by ducting some bypass air from the fan through ducts 1 3 (Figure 4) to the base of the side channels. Further ducts 14 may be provided to improve the flow of air at the back part of the air space 10. Mixing can be further enhanced by drawing up cool air by the use of properly placed baffles 1 5 (Figure 4).

The mixed air rises by convection to emerge from vents 12. With the arrangement described it is found that the emerging air can be only 1200C whereas the internal temperature of the blocks may be as high as 7000C.

The rate of forced air flow is important. In this embodiment the fan is rated at 60 cubic feet per minute which gives a total air flow rate of substantially three times the natural convection rate for the heater at the same temperatures. The factor of three is found to be a useful practical rule for good results.

1. A storage heater comprising: two stacks of thermal blocks facing each other with an air-gap therebetween; thermal insulation surrounding the pair of stacks and blocking the air-gap at the top and sides; two baffles extending vertically from the bottom to near the top of the air-gap, so dividing the air-gap into a central channel and two side channels; a blower fan at the base of the central channel; and a cabinet enclosing the stacks and the fan and defining an air space around the insulation, the cabinet having inlet vents at the bottom and outlet vents at the top, the arrangement being such that air is drawn in by the fan, is blown up the central channel, is directed down the side channels, mixes with cool ambient air at the base of the dabinet and rises in the air space to emerge from the top.

2. A storage heater as claimed in Claim 1 wherein the fan has by-pass outlets to the base of each side channel to enhance mixing of the hot air with cold air.

3. A storage heater as claimed in either of the preceding claims wherein the capacity of the fan is such as to give an air flow rate of substantially three times the natural convection rate from the heater at the same temperature.

4. A storage heater substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fan assisted storage heater The invention relates to a storage heater having a fan to assist in removing heat by forced draught. A storage heater generally comprises a stack of thermal blocks -- typically of concrete -- with an electric heating element running through them. Cheap rate electricity at night is used to heat the blocks and they heat the air during the day, Such a heater can become extremely hot inside. In order to remove the heat efficiently it has been proposed to provide a duct within the blocks and to blow air through the duct by means of a fan. Such arrangements have been found to be impracticable because the temperature of the emerging air is dangerously high. The present invention seeks to provide an improved fanassisted storage heater. According to the invention there is provided a storage heater comprising: two stacks of thermal blocks facing each other with an air-gap therebetween; thermal insulation surrounding the pair of stacks and blocking the air-gap at the top and sides; two baffles extending vertically from the bottom to near the top of the air-gap, so dividing the airgap into a central channel and two side channels; a blower fan at the base of the central channel; and a cabinet enclosing the stacks and the fan and defining an air space around the insulation, the cabinet having inlet vents at the bottom and outlet vents at the top, the arrangement being such that air is drawn in by the fan, is blown up the central channel, is directed down the side channels, mixes with cool ambient air at the base of the cabinet and rises in the air space to emerge from the top. With this arrangement efficient heat transfer is possible and the hot air mixes with cool air to emerge at a satisfactory temperature. Preferably the fan has by-pass outlets to the base of each side channel to enhance mixing of the hot air with cool air. The invention will further be described with reference to the accompanying drawings, of which: Figure 1 is a cross-sectional front elevation; Figure 2 is a view from beneath the heater of Figure 1; Figure 3 is a cross-sectional side elevation taken at 'A-A' in Figure 1; and Figure 4 is a cross-sectional side elevation taken at 'B-B' of Figure 1. Referring to the drawings the heater comprises two stacks 1 and 2 of thermal blocks of concrete. Electric heating elements 3 run through the blocks. The stacks are spaced apart to define a vertical air-gap 4. Two vertical baffles 5 divide the air-gap into a central channel 4a and two side channels 4b and 4c. A layer of thermal insulation 6 encloses the stacks and blocks the top and sides of the air-gap. A centrifugal fan 7 is driven by an electric motor 8 and is mounted at the base of the central channel 4a. A cabinet 9 encloses the thermal blocks and fan and defines an air space 10 around the insulation. Inlet vents 11 are provided at the base of the cabinet and outlet vents 1 2 at the top. In operation, the blocks are heated during the night and in the morning the fan is started. l his draws air in through vents 11 and directs the air up the channel 4a and down channels 4b and 4c. The air is heated in the air-gap and the hot air mixes with cool air admitted in to the vents 11. The mixing effect is enhanced by ducting some bypass air from the fan through ducts 1 3 (Figure 4) to the base of the side channels. Further ducts 14 may be provided to improve the flow of air at the back part of the air space 10. Mixing can be further enhanced by drawing up cool air by the use of properly placed baffles 1 5 (Figure 4). The mixed air rises by convection to emerge from vents 12. With the arrangement described it is found that the emerging air can be only 1200C whereas the internal temperature of the blocks may be as high as 7000C. The rate of forced air flow is important. In this embodiment the fan is rated at 60 cubic feet per minute which gives a total air flow rate of substantially three times the natural convection rate for the heater at the same temperatures. The factor of three is found to be a useful practical rule for good results. CLAIMS

1. A storage heater comprising: two stacks of thermal blocks facing each other with an air-gap therebetween; thermal insulation surrounding the pair of stacks and blocking the air-gap at the top and sides; two baffles extending vertically from the bottom to near the top of the air-gap, so dividing the air-gap into a central channel and two side channels; a blower fan at the base of the central channel; and a cabinet enclosing the stacks and the fan and defining an air space around the insulation, the cabinet having inlet vents at the bottom and outlet vents at the top, the arrangement being such that air is drawn in by the fan, is blown up the central channel, is directed down the side channels, mixes with cool ambient air at the base of the dabinet and rises in the air space to emerge from the top.

2. A storage heater as claimed in Claim 1 wherein the fan has by-pass outlets to the base of each side channel to enhance mixing of the hot air with cold air.

3. A storage heater as claimed in either of the preceding claims wherein the capacity of the fan is such as to give an air flow rate of substantially three times the natural convection rate from the heater at the same temperature.

4. A storage heater substantially as hereinbefore described with reference to the accompanying drawings.