GB2220260A

GB2220260A - Improvements in or relating to central heating systems

Info

Publication number: GB2220260A
Application number: GB8813253A
Authority: GB
Inventors: Alastair Ian Morrison
Original assignee: BOYDSLAW
Current assignee: BOYDSLAW
Priority date: 1988-06-04
Filing date: 1988-06-04
Publication date: 1990-01-04
Also published as: GB8813253D0

Abstract

A secondary, electric water heater (30) for incorporation in a central heating system comprising a primary water heater (32), a plurality of radiators (38) and a pump (40) for pumping water around the system. The secondary heater (30) has a second pump (42) associated therewith, and is adapted to heat water to a predetermined temperature as it flows through the heater. It is particularly intended for use in a solid fuel system to provide heat whenever it is inconvenient to use the primary, solid fuel, heater (32), and to conserve fuel by eliminating the need to bank-up the primary heater at night or during the day. <IMAGE>

Description

"Improvements in or Reiáting to Central Heaing Systems" The present invention relates to central heating systems, and is particularly concerned with a secondary heating means, connectable into a central heating circuit so as to heat water as it is pumped around the circuit.

It is a problem common to many conventional central heating systems that it is necessary to heat up a relatively large reservoir of water before individual radiators begin to provide heat to the premises in which the system is installed. This is a particular problem with solid fuel systems in a domestic environment, where it is often the case that a home is cold first thing in the morning or upon returning after a day's work. Hitherto, the only alternative to this has been for the occupant to "bank up" the heating boiler overnight or during the day, however this is obviously extremely wasteful of fuel.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.

Accordingly, the invention provides a secondary water heating means, adapted to be incorporated in a central heating system including a primary water heating means, a plurality of radiators, and first pump means for pumping water around said system, said secondary heating means having inlet and outlet means connectable to said system and having associated therewith second pump means adapted to pump water through said secondary heating means and around said radiators, and being adapted to heat said water to a predetermined temperature as the water flows therethrough.

The power supply for said secondary heating means and second pump means is preferably controlled by programmable timing means.

Preferably also, said secondary heating means comprises a closed vessel having an inlet and an outlet and enclosing at least one electrical heating element, said outlet being connectable to the inlets of said radiators via said second pump means, wherein the power rating of said element or elements is determined according to the volume of the vessel, the volume flow rate of the second pump means, and the desired water temperature at the outlet.

Preferably also, said predetermined temperature is set by a control thermostat. A second, limit thermostat may also be provided.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which; Fig. 1 is a sectional side view of a water heater embodying the invention; Fig. 2 is an end view of the heater of Fig. 1; Fig. 3 is a schematic representation of a central heating system incorporating the invention; and Fig. 4 is a wiring diagram illustrating the power supply and control means for the invention.

Referring now to Figs. 1 and 2 of the drawings, a secondary water heater 10 for a central heating system comprises a closed, generally rectangular vessel 12, suitably of 3mm steel, having a top wall 14 through which extend, into the interior of the vessel 12, four electric immersion heating elements 16. The elements 16 may be screwed into four threaded steel rings 18 welded to the top wall 14. Inlet and outlet connector bosses 20 and 22, which communicate with the interior of the vessel 12, are welded to a side wall 24 adjacent the bottom and top thereof respectively. A base member 26, closing the bottom of the vessel 12, may be fitted with levelling screws 28 at each corner.

Fig. 3 illustrates the manner in which a secondary water heater 30, such as that of Fig. 1, may be incorporated into a solid fuel central heating system. The basic system comprises a coal-fired water boiler 32, a hot water tank 34, a header tank 36, a plurality of radiators 38 and first pump means 40, interconnected by pipes as shown. The system is modified, in accordance with the invention, by the addition of the secondary heater 30 and a second pump means 42. The inlet 44 of the heater 30 is connected to the outlets 46 of the radiators 38 and to the header tank 36, whilst the outlet 48 of the heater 30 is connected, via the second pump means 42, to the inlets 50 of the radiators. As can be seen from the drawing, the second pump means 42 opposes the first pump means 40, which will normally be turned off while the second pump means 42 is operating.

Fig. 4 illustrates the connection of the elements 16 of the secondary heater 10 or 30 and the second pump means 42 to a mains electrical supply 52, and also the connection of control means for controlling their operation. The elements 16 have their live terminals connected to the mains 52 via a contactor 54 and fuses (typically 15 amp) 56. The second pump means 42 is also connected to the mains 52 as shown. The contactor 54 controls the power supply to the elements 16 and is itself controlled, firstly, by a programmable time clock 58 (which also controls the power supply to the second pump means 42, and is connected to the mains 52 via a 5 amp fuse 64), secondly, by a control thermostat 60 which allows the desired water temperature to be set, and, thirdly, by a limit thermostat 62 which acts as a safety cut-off.

The total power rating of the elements 16 may be selected according to the volume flow rate of the second pump means 42, the volume of the vessel 12, and the maximum desired water temperature, so as to heat the water rapidly to a pre-set temperature as it is pumped through the heater 10 or 30, thus allowing the radiators to be heated up quickly whenever required. The timeclock 58 allows this to be done automatically so that a home may be heated up shortly before the occupants rise in the morning (in which case it is possible to take advantage of cheap, off-peak electricity rates) or during the day before they return from work.

A secondary heater as herein described can bring central heating radiators up to temperature within five minutes and obviates the need to bank up solid fuel boilers at night or during the day, so providing considerable savings in fuel costs. Where cheap-rate electricity can be used, it may also be cheaper to run than oil, mains gas or liquid petroleum gas systems.

Claims

1. A secondary water heating means, adapted to be incorporated in a central heating system including a primary water heating means, a plurality of radiators, and first pump means for pumping water around said system, said secondary heating means having inlet and outlet. means connectable to said system and having associated therewith second pump means adapted to pump water through said secondary heating means and around said radiators, and being adapted to heat said water to a predetermined temperature as the water flows therethrough.

2. The invention of claim 1 wherein the power supply for said secondary heating means and second pump means is preferably controlled by programmable timing means.

3. The invention of claim 1 or claim 2 wherein said secondary heating means comprises a closed vessel having an inlet and an outlet and enclosing at least one electrical heating element, said outlet being connectable to the inlets of said radiators via said second pump means, wherein the power rating of said element or elements is determined according to the volume of the vessel, the volume flow rate of the second pump means, and the desired water temperature at the outlet.

4. The invention of any of claims 1 to 3 wherein said predetermined temperature is set by a control thermostat.

5. The invention of any of claims 1 to 4, further including a limit thermostat.

6. A secondary water-heating means substantially aS hereinbefore described with reference to the accompanying drawings.