Control for a tankless water heater used with a solar water heating system

Abstract

A tankless water heating auxiliary system for a solar water heating system, includes a solar collector; a tankless water heater auxiliary system; an insulated water storage tank storing the potable water; a heat exchange system for heating stored water; and piping for connecting the collector, the storage tank and the heat exchanger in fluid communication. A first sensor is connected to and located adjacent the storage tank for sensing the temperature of the stored water at an outlet of the tank. A method for controlling initiation of heating in a tankless water heater auxiliary system, includes monitoring operation of a tankless water heater; measuring water flow using a water flow sensor to determine if water flow rate exceeds a use determined flow rate; implementing a control time delay into the tankless water heater to purge water from the heater and sense the inlet water supply temperature; measuring the water temperature using a heat exchanger outgoing thermistor; comparing the temperature measured by the thermistor to a predetermined temperature; and initiating a combustion sequence if the temperature measured by the outgoing themistor is less than the predetermined temperature.

Description

BACKGROUND OF THE DISCLOSURE[0001]The disclosure relates to a control for a tankless water heater serving as an auxiliary heater for a solar water heating system.[0002]Solar water heating systems are made up of components that collect solar energy, transfer the energy to the potable water via a heat exchanger, store the thermal energy, control system operations, deliver hot water where it is needed, and protect the system against freezing. Components can be combined in a variety of ways, but these six basic functions must be met, although some systems are simple enough that passive physics provide the control and motive forces to drive the fluids and heat transfer in the system. The systems also typically include an auxiliary heating system for when the solar heating is insufficient to meet hot water usage.[0003]Solar water heating systems can generally be described using the following four terms: direct or indirect and passive or active. Direct systems heat the potable water direct...

AI Technical Summary

Benefits of technology

[0012]Another aspect of the disclosure is a solar water heater system employing a tankless, (instantaneous) inline heater as an auxiliary which is controlled using a sensor configuration which determines the stored water temperature as a condition for initiating the powering or combustion sequence for the auxiliary heater. The sensor configuration eliminates needless cycling of auxiliary systems and reduces energy consumption.

[0013]Another aspect of the disclosure is to place an auxiliary control sensor at the outlet or top of the solar water storage tank which senses the water delivered to the tankless auxiliary and prevent needless powering of the auxiliary power system. This solution would reduce energy consumption and reduce the number of operation cycles of the auxiliary, improving reliability.

[0014]Another aspect of the disclosure is reduced energy consumption in the range of $20-$40 annually and a reduction in the number of operation cycles, improving system reliability.

Problems solved by technology

Since this approach requires two storage tanks, significant floor space is needed to accommodate the arrangement.

While this system supplies a consistent and immediate supply of heated water, it consumes excessive energy to maintain the circulation loop temperature and requires additional equipment at the time of installation.

The conventional tankless operation control does not make provision for incoming water supply, previously heated at or above the set tankless units point, and as a result needless heating evens are initiated consuming unneeded energy and increasing the number of heating system operating cycles contributing to a shortened life of the equipment.

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