GB2203213A

GB2203213A - Frost protection system for water pipes

Info

Publication number: GB2203213A
Application number: GB08707865A
Authority: GB
Inventors: Donald Edgar Bromley; Elizabeth Mary Bromley
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-04-02
Filing date: 1987-04-02
Publication date: 1988-10-12
Also published as: GB8707865D0

Abstract

A frost protection system for water pipes prevents freezing by means of an electric heater which consists of copper wires surrounded by electrical insulation. It is most beneficial when the heater is fitted under thermal insulation fitted to the pipes but it may be used on uninsulated pipes. It may be used with a control device which contains a thermostat to initiate operation at low temperature and which may optionally include other informative or protective devices such as a temperature indicator or a frost alarm. <IMAGE>

Description

FROST PROTECTION SYSTEM FOR WATER PIPES This invention relates to a frost protection system for water pipes.

Freezing of water in pipework is a common domestic problem and has well known associated risks of water damage to house contents and structure. The problem has possibly become more prominent of late as it has become common and recommended practice for improvement of the heating within the living area, to thermally insulate loft spaces where such pipework usually is. Although the pipes are themselves insulated the residual heating is less and the risk of freezing is greater than in uninsulated lofts. The danger is greatest when there is an unexpected cold change in the weather.

In modern house designs the total pipework may be arranged to run within the heated space. Otherwise provision of a frost thermostat system in the loft is possible, but the difficulty there is that a substantial heat input is required, which defeats the object of the loft thermal insulation as well a having a perceived fire risk.

Otherwise it has been supposed that special and expensive heaters would be necessary to use on the pipework. Only a little heat is however required within the pipework itself. For a well insulated 15 mm. pipe only 2 watts per metre is enough to raise the temperature by about 1Q C. and even on an uninsulated pipe by about 3 C. The length of piping in most domestic lofts is under 5# m and requires only i## watts.

ficcording to the present invention this relatively small power is provided by a low voltage electric heater with a current of a few Amperes in a small gauge insulated copper wire such as is readily available and widely used for electrical and electronic circuits. This class of wire or flex has PVC insulation of l~~~ V. rating at 80 C. It is likely to be convenient in practice for twin wires to be used having an outward and a return circuit. That the voltage remains small and the supply can be isolated from the mains by a transformer ensures electrical safety. The ensuing table lists characteristics of some available wires.

TABLE Wire type Resistance 1 W/m double pass 2 W/m single pass ohms/metre Current-A V-olts/l~~m Current-A Volts/l~~m 18/8.lmm ~.216 2.15 92 3184 7/#.2mm ~.~78 3.58 56 1/#.6mm ~.~6~ 4.~8 50 5.76 35 16/0.2mum ~.~34 5.42 36 7.68 25 A specific embodiment of the invention is now described by way of example with reference to the accompanying drawing in which Figure 1 is a block diagram of a complete system.

Figure 2 is a perspective diagram of the heater wire installed on an insulated pipe.

Referring to the drawing fig 1 there is a temperature sensor 1 which is mounted in a position exposed to cold weather such as under the eaves of the house or within the loft. A thermistor is a convenient form of sensor for the purpose, but many suitable electrical and expansion devices are well known. The sensor drives an interface 2 giving a voltage corresponding to the temperature. So far as the main function is concerned, a trigger circuit 5 set to operate when the temperature falls to zero or thereabouts in turn drives a relay 6 which applies mains electricity to the transformer 7. The interface may optionally be made to operate also a visual indicator 3 and alternatively or additionally an alarm 4.

The transformer then drives the heater 8 which is laid as in fig 2 along the whole pipework 9 within the insulation 15 of foamed plastic or other material. The wires may be fastened with adhesive tape if required. It will normally be convenient to provide supply and return lines along each pipe but it is possible for the supply and return to take distinct routes.

Claims

1 A frost protection system for water pipes which includes an electric heater consisting of a flexible copper wire in an electrically insulating coating.

2 A frost protection system as claimed in claim 1 in which the heater is fitted under thermal insulation of water pipes.

3 A frost protection system as claimed in claim 1 or claim 2 wherein the heater is controlled by a thermostat.

4 A frost protection system as claimed in claim 1 or claim 2 or claim 3 wherein the heater operates through a low voltage transformer from the electric mains.