Thermostatic mixing valve

Abstract

A thermostatic mixing valve having a hot water inlet for connection to a supply of hot water, a cold water inlet for connection to a supply of cold water, an outlet for temperature controlled water and a valve device for controlling the relative proportions of hot and cold water admitted to a mixing chamber. The outlet communicates with the mixing chamber to receive temperature controlled water having a desired temperature. A temperature control adjusts the valve device in accordance with the desired temperature of the temperature controlled water where the valve device and the mixing chamber form flow passages for the incoming streams of hot and cold water and are configured such that the velocity of the incoming water streams is maintained and the incoming water streams are turned to flow in the same direction so that flow of one stream can entrain and assist flow of the other stream.

1 . A thermostatic mixing valve having a hot water inlet for connection to a supply of hot water, a cold water inlet for connection to a supply of cold water, an outlet for temperature controlled water, valve means for controlling the relative proportions of hot and cold water admitted to a mixing chamber, the outlet communicating with the mixing chamber to receive temperature controlled water having a desired temperature, temperature control means for adjusting the valve means in accordance with the desired temperature of the temperature controlled water, wherein the valve means and the mixing chamber together form flow passages for the incoming streams of hot and cold water and are configured such that the velocity of the incoming water streams is maintained and the incoming water streams are turned to flow in the same direction so that flow of one stream can entrain and assist flow of the other stream. 
   
   
       2 . A thermostatic mixing valve according to  claim 1  wherein the valve means is configured to increase the flow of the cold stream by an increase in pressure of the hot stream for maintaining the initial proportions of hot and cold water admitted to the mixing chamber and assisting the response of the temperature control means to maintain the desired temperature. 
   
   
       3 . A thermostatic mixing valve according to  claim 1  wherein the valve means is configured to cause the hot and cold streams to enter the mixing chamber in a radial direction and turn in an axial direction to merge within the mixing chamber. 
   
   
       4 . A thermostatic mixing valve according to  claim 1  wherein the mixing chamber has radially inner and outer walls including curved surfaces configured so that the inner wall assists turning one of the streams and the outer wall assists turning the other stream. 
   
   
       5 . A thermostatic mixing valve according to  claim 4  wherein the inner wall is configured so that turning the water stream by the inner wall is assisted by the Coanda effect. 
   
   
       6 . A thermostatic mixing valve according to  claim 1  wherein the valve means is configured so that the hot and cold streams enter the mixing chamber close together in the axial direction of flow whereby each stream can entrain and assist flow of the other stream and an increase in pressure of either stream increases the flow of the other stream to assist the response of the temperature control means to maintain the desired temperature. 
   
   
       7 . A thermostatic mixing valve according to  claim 1  wherein the valve means is configured so that the hot and cold streams enter the mixing chamber at substantially the same axial position so that the streams are brought together and merge quickly to promote mixing of the streams. 
   
   
       8 . A thermostatic mixing valve according to  claim 1  wherein the valve means is configured so that both streams are matched and any asymmetry is cancelled out when the streams merge within the mixing chamber. 
   
   
       9 . A thermostatic mixing valve according to  claim 1  wherein the mixing chamber has a cross-sectional area perpendicular to the direction of flow that is matched to the combined cross-sectional areas of the hot and cold flows through the valve means. 
   
   
       10 . A thermostatic mixing valve according to  claim 9  wherein the cross-sectional area of the mixing chamber is from 1 to 1.5 times the combined cross-sectional areas of the hot and cold flows. 
   
   
       11 . A thermostatic mixing valve according to  claim 9  wherein the cross-sectional area of the mixing chamber is from 1 to 1.25 times the combined cross-sectional areas of the hot and cold flows. 
   
   
       12 . A thermostatic mixing valve according to  claim 9  wherein the axial length of the mixing chamber is at least 5 times the width of the mixing chamber. 
   
   
       13 . A thermostatic mixing valve according to  claim 9  wherein the axial length of the mixing chamber is 5 to 10 times the width of the mixing chamber. 
   
   
       14 . A thermostatic mixing valve according to  claim 1  wherein the mixing chamber has an annular ring shape between inner and outer walls and is configured to provide substantially unobstructed flow with a gradual increase in cross-sectional area in the direction of flow. 
   
   
       15 . A thermostatic mixing valve according to  claim 1  wherein the valve means comprises a main body having the inlets for connection to the hot and cold supplies and the outlet for connection to an ablutionary appliance, the main body further having an opening for reception of a cartridge unit housing the valve means, wherein the cartridge unit carries seals for sealing the cartridge unit in the valve body and the seals are O-rings of decreasing diameter from the outer end to the inner end of the cartridge unit to provide clearance for insertion of the cartridge unit.