GB2209594A

GB2209594A - Central heating system

Info

Publication number: GB2209594A
Application number: GB8820701A
Authority: GB
Inventors: Patrick William Whitham
Original assignee: PRESSURE UNITS Ltd
Current assignee: PRESSURE UNITS Ltd
Priority date: 1987-09-08
Filing date: 1988-09-01
Publication date: 1989-05-17
Also published as: GB8820701D0; GB8721090D0

Abstract

A sealed central heating system has high and low pressure sides separated by a pressure control valve (14) and with a gas charged expansion vessel (15) on the low pressure side of the system. Water expelled from the high pressure side of the system through expansion on heating is accommodated in the expansion vessel and is returned by a pump (18) from the expansion vessel as the high pressure side of the system cools. <IMAGE>

Description

CENTRAL HEATING SYSTEM This invention concerns a central heating system and more particularly a sealed central heating system of the kind (hereinafter termed of the kind referred to) comprising a pressure control valve which separates a high pressure side including the boiler and heating circuit from a low pressure side including a reservoir for the supply of make-up water to the system by means of a pump.

In a conventional system of the kind referred to an expansion storage vessel is connected with the high pressure side of the system and accomodates the expansion in the volume of the water as it is heated. A gas charge in the head of the storage vessel forces water back into the system as it contracts on cooling.

Such conventional system has a number of disadvantages. The volume of the gas charge in the expansion vessel must be substantial if variations in the volume of water in the high pressure side of the system are not to be accompanied by excessive variations in pressure. Again, a considerable volume of water may leak from the system before producing a pressure drop sufficient to activate the make-up systems.

The present invention proposes arrangements which overcome at least to an extent the problems aforesaid.

According to the invention there is provided a sealed central heating system of the kind referred to characterised by the provision of an expansion storage vessel connected with the low pressure side of the system and in that said pump also acts to pump water from the storage vessel to the high pressure side of the system all to maintain the pressure in the high pressure side of the system substantially constant as the water is heated and cools.

Such expansion vessel may have a gas charge of relatively small capacity since relatively large variations in pressure in the low pressure side of the system can readily be tolerated. Any loss of water from the high pressure side of the system results in an immediately detectable pressure drop to enable operation of the make-up system.

The invention will be further apparent from the following description with reference to the single figure of the accompanying drawing which shows, by way of example only, one form of sealed central heating system embodying same.

Referring now to the drawing it will be seen that the system comprises a boiler 10 and heating circuit supplying a plurality of radiators 11. Heated water from the boiler is pumped around the circuit by pump 12 in response to time-clock and thermostat control devices.

The parts described thus far are on the high pressure side of the system and separated from the low pressure side by a pressure control valve 14. Connected with the low pressure side of the system is a gas charged expansion storage vessel 15. A reservoir 16 for the supply of make-up water is connected with the low pressure side of the system by way of a non-return valve 17.

A pump 18 in series with a non-return valve 19 is connected across the pressure control valve 14.

The pump 18 operates in response to a drop in pressure in the high pressure side of the system as detected by a pressure sensor 20.

In use as water expands thermally in the high pressure side of the system excess volume flows through valve 14 and into expansion storage vessel 15. As the water contracts on cooling pump 18 draws water from vessel 15 and returns it to the high pressure side of the system, all to maintain the pressure in the high pressure side of the system at or about a predetermined value.

Any water loss through leakage from the high pressure side of the system is made good by pump 18 drawing from reservoir 16.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible, without departing from the scope thereof.

Claims

1. A sealed central heating system of the kind referred to characterised by the provision of an expansion storage vessel connected with the low pressure side of the system and in that said pump also acts to pump water from the storage vessel to the high pressure side of the system all to maintain the pressure in the high pressure side of the system substantially constant as the water is heated and cools.

2. A sealed cental heating system according to claim 1 wherein said expansion vessel has a gas charge of relatively small capacity.

3. A sealed central heating system according to either claim 1 or claim 2 wherein said reservoir is connected to the system by way of a non-return valve.

4. A sealed central heating system according to any preceding claim wherein said pump in series with a non-return valve is connected across said pressure control valve.

5. A sealed central heating system of the kind referred to and substantially as described herein with reference to and as illustrated by the single figure of the accompanying drawing.