Performance standards for plumbing products in general and faucet systems in particular are being required by more and more communities for both residential and commercial construction. The standards which are being adopted include standards relating to maintaining mixed water temperature as well as standards relating to high temperature limits for the mixed water supply for the faucet systems.
A pressure balancer is used in a hot/cold water supply system to meet the first standard noted above and maintain mixed water temperature in response to pressure fluctuations in the hot or cold water supply lines. The pressure balancer is designed to operate in a commercial system where the hot water pressurization system is separate from the cold water pressurization system and in a residential system where the pressurization of the hot and cold water systems is common. When water is demanded by a user for showering, the user adjusts the mixing valve to attain a desired temperature of the mixed hot and cold water. If, during the course of showering, the cold water pressure fails or drops significantly, the user is then subjected instantaneously and unexpectedly to an increase in the temperature of the mixed hot and cold water. This could result in serious scalding of the user. Similarly, if the hot water pressure fails or drops significantly, the user is subjected instantaneously and unexpectedly to a decrease in the temperature of the mixed hot and cold water. While this situation is not as potentially harmful to the user's well being as a reduction in the cold water pressure, the reduction of the hot water pressure can still be startling and extremely unpleasant.
The pressure balancer is incorporated into the hot and cold water supply systems to eliminate the unexpected reaction to the reduction of either the hot or cold water supply pressure. The pressure balancer operates to shut off the supply of hot or cold water upon a failure of the pressurized supply of the other. The pressure balancer also responds to changes in the pressure of the hot and cold water supplies where the changes in pressure are sufficient to alter the mix ratio of the hot and cold water and thus the temperature of the mixed water. The pressure balancer responds to the pressure fluctuations by balancing or equalizing the water flow on the hot water side and the cold water side of the pressure balancer to maintain the mix ratio of the hot and cold water and thus maintain the temperature of the mixed water.
The second standard which is being adopted is a high temperature limit control for faucet systems. The high temperature limit control is designed to limit the hot water temperature which is available from the hot water supply system to a level which will prevent scalding of an individual. The high temperature limit control can be accomplished by placing a stop on a single handle faucet which prohibits the movement of the handle to a position which provides full hot water flow with no cold water flow. Thus, a combination of hot and cold water will always be supplied to the mixing valve thereby limiting the temperature of the mixed water. The stop for the single handle faucet is preferably designed with adjustability in order to compensate for varying supply temperatures of the hot and cold water systems.
Another method for accomplishing the high temperature limit control is to mechanically link the hot and cold water control valves with a lost motion device in an two/three handle faucet in order to provide the mixing of cold water with the hot water to limit the temperature of the supplied water. While this approach is feasible, the intricacies of the mechanism, the potential high cost of the mechanism and the durability of the mechanism prohibit the development of faucet systems using this concept.
Thus, there is a need for a two/three faucet system which incorporates a pressure balancer and a high temperature limit control in a simplified and cost effective manner. The faucet system should incorporate both of these controls while still maintaining convenience to the user for adjustability as well as accessibility to the inner working of the faucet system for maintenance purposes.