Lead Lag Control System for Water Heaters

Abstract

A control system is shown for a series of two or more water heaters arranged in parallel. A cold water supply line delivers cold water from a cold water source to a cold water inlet at each of the respective two or more water heaters arranged in parallel. A low pressure restriction is present at each cold water inlet of the water heaters which presents a low pressure restriction to the flow of cold water at each cold water inlet. A by-pass valve is also present at the cold water inlets for by-passing cold water from the cold water supply line around each of the low pressure restrictions. A hot water discharge line receives and discharges hot water from each of the water heaters. A controller is used to control when each of the by-pass valves will be open or closed based upon demand with only the by-pass valves being open which are needed to meet demand placed upon the system.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The present application claims priority from the earlier filed provisional application, Ser. No. 62 / 089,597, filed Dec. 9, 2014, entitled “Lead Lag Control System for Water Heaters.”BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates generally to water heater systems and control methods for water heaters and, more specifically, to a simplified lead lag, control system for a series of two or more water heaters arranged in parallel.[0004]2. Description of the Prior Art[0005]Water heaters are used in a large variety of residential, commercial and industrial settings. For example, large storage tank systems are often found in hospitals and institutions, industrial plants, schools, universities, apartment complexes, and the like. The different types of water heaters which are used to supply hot water to these systems may use various sources of energy, such as gas, oil, electricity, boiler water or steam...

AI Technical Summary

Benefits of technology

The patent describes an improved control system for multiple water heaters that work together. The system includes a cold water supply line, a hot water discharge line, and a controller that controls when valves will be opened or closed to meet demand. The system also uses a by-pass valve to direct water from the cold supply line around the valves to prevent pressure drop and compensate for increased demand. The technical effects of this system include improved efficiency, better control over water temperature, and reduced pressure drop.

Problems solved by technology

However, water heating systems presently available or prior art water heating systems sometimes fall short when attempting to maintain a water output at a constant predetermined temperature level during rapid shifts or during fluctuations in water demand.

As a result, during a rapid increase in water demand, a user might experience a sudden drop in water temperature or a cold water splash.

Conversely, during a rapid decrease in water demand, a user might experience a sudden spike in water temperature.

However, starting up and shutting down each water heater is inefficient due to the pre-purge and post-purge operations involved.

This system certainly works, but the large motorized valves are expensive.

If they fail, they have the potential to shut down the hot water system in the building.

The electronic controller is also somewhat expensive.

The logic / sensing of when and how many to have open can be complicated.

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