Measuring magnetite buildup in a magnetic filter

Abstract

A magnetite level monitoring device for a magnetic filter in a central heating system, the magnetic filter including a separation chamber, an inlet to the chamber and an outlet from the chamber, and a magnetic element disposed within the chamber for attracting magnetic particles and removing the magnetic particles from the system water as it flows through the chamber, and the monitoring device including: a housing for placing adjacent to the outside of the separation chamber; a magnetometer mounted to the housing; a magnetic field guide mounted to the housing, the magnetic field guide being disposed between the magnetometer and the outside of the separation chamber, when the housing is mounted to the separation chamber; and output means adapted to issue a notification when the output from the magnetometer exceeds a predetermined threshold.

What is claimed is: 
     
         1 . A method of measuring the amount of magnetite captured by a magnetic filter in a central heating system,
 the magnetic filter including a separation chamber, an inlet to the chamber and an outlet from the chamber, and a magnetic element disposed within the chamber for attracting magnetic particles and removing the magnetic particles from the system water as it flows through the chamber,   and the method comprising the steps of:
 providing a magnetometer positioned on the housing at a fixed point relative to the magnetic element, the fixed point being a predetermined distance from an end of the filter; 
 measuring the output from the magnetometer when the filter is empty of magnetite; 
 monitoring the output of the magnetometer; and 
 issuing an indication on an output means when the output from the magnetometer exceeds or drops below a predetermined threshold, the predetermined threshold being calculated by adding a fixed offset to the output from the magnetometer measured when the filter is empty of magnetite. 
   
     
     
         2 . The method of  claim 1 , in which the magnetometer is provided on a fixed point on the outside of the chamber. 
     
     
         3 . The method of  claim 1 , in which a magnetic field guide is provided for guiding magnetic field lines to a region where the magnetometer is located. 
     
     
         4 . The method of  claim 3 , in which the magnetic field guide is provided between the magnetometer and the magnetic element. 
     
     
         5 . The method of  claim 3 , in which the magnetic field guide is made from metal. 
     
     
         6 . The method of  claim 5 , in which the magnetic field guide is made from stainless steel. 
     
     
         7 . The method of  claim 6 , in which the magnetic field guide is made from stainless steel grade 430. 
     
     
         8 . The method of  claim 1 , further including the steps of sampling and recording the magnetometer reading and determining a rate of change from the recorded readings. 
     
     
         9 . The method of  claim 8 , in which the rate of change is recorded at intervals. 
     
     
         10 . The method of  claim 9 , in which an indication is issued on the output means if the rate of change increases. 
     
     
         11 . The method of  claim 1 , in which a pressure sensing means is provided for sensing the static pressure within the separation chamber, and the method including the step of sampling and recording static pressure measurements. 
     
     
         12 . A magnetite level measuring device for a magnetic filter in a central heating system, the magnetic filter including a separation chamber, an inlet to the chamber and an outlet from the chamber, and a magnetic element disposed within the chamber for attracting magnetic particles and removing the magnetic particles from the system water as it flows through the chamber,
 and the measuring device including:   a housing for placing in a fixed position relative to the magnetic element;   input means for accepting a notification that the filter is empty of magnetite; and   output means adapted to issue a notification when the output from the magnetometer exceeds or drops below a threshold, the threshold being calculated in response to the notification on the input means by adding a fixed offset to the output of the magnetometer at the time when the notification is received.   
     
     
         13 . The magnetite level measuring device of  claim 12 , adapted to monitor the output from the magnetometer and issue the notification whenever the output from the magnetometer exceeds or drops below a predetermined threshold. 
     
     
         14 . The magnetite level measuring device of  claim 12 , in which a magnetic field guide is mounted to the housing. 
     
     
         15 . The magnetite level measuring device of  claim 12 , in which storage means are included for storing a plurality of magnetometer readings. 
     
     
         16 . The magnetite level measuring device of  claim 15 , adapted to periodically sample the magnetometer reading and record the reading on the storage means. 
     
     
         17 . The magnetite level measuring device of  claim 16 , adapted to calculate a rate of change over time of the recorded magnetometer readings. 
     
     
         18 . The magnetite level measuring device of  claim 17 , adapted to record the rate of change at intervals. 
     
     
         19 . The magnetite level measuring device of  claim 18 , adapted to issue a notification on the output means if the rate of change increases. 
     
     
         20 . A magnetite level magnetic filter including a separation chamber, an inlet to the chamber and an outlet from the chamber, and a magnetic element disposed within the chamber for attracting magnetic particles and removing the magnetic particles from the system water as it flows through the chamber, the magnetic element including a stack of substantially cylindrical magnetic billets having north and south poles which are nominally on opposing flat faces of the billets, the billets being disposed with like poles facing each other,
 and the magnetite level measuring device of  claim 12 ,   the housing of the measuring device being fixed to the chamber and held in a fixed position relative to the chamber, adjacent to the outside of the chamber.