The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Hot Water Suply
With this scheme, in ordinary domestic practice, the water in the storage tank f seldom becomes warmer than 180°F. It is possible to insert in the return circulating pipe e, between the transfer heater and the boiler, a thermostatic valve which throttles, but does not shut off tightly, the circulation, and which can easily be adjusted to prevent over- heating of the water in the storage tank.
31. In the installation shown in Fig. 15 an oil burner r, controlled by a room thermostat s, supplies the heat for the boiler b, but the boiler can be heated by solid fuel, either manually or stoker fired, or it may be heated by gas. The installation operates equally well if the heating of the house is accomplished by hot water, provided that the boiler water is kept about 20 degrees warmer than the desired domestic-water temperature. This usually is accomplished by circulating the water from the boiler to the radiators of the heating system by means of a pump. In this case an automatic check-valve is provided in the flow main which prevents circulation unless the pump is running.
The room thermostat then controls the intermittent operation of the pump, and an aquastat t in the boiler water controls the operation of the oil or gas burner, stoker, or draft dampers. Where the domestic hot-water demand is heavy, as in large buildings, a battery of several large transfer heaters frequently is employed. The copper coils can be easily removed for cleaning, but, owing to the comparatively low temperature at which heat transfer occurs, there is little tendency for formation of scale on the interior of the coils.
32. Economical Device for Heating Water by Transfer. A further development of water heating by transfer is illustrated in Fig. 16. In the device shown, two copper-tube manifolds a are mounted inside a U tube b which, in turn, is installed inside the insulated storage tank c. Hot water from the heating boiler enters the tube b through the pipe d, passes through the tube, and returns to the boiler through the pipe e. Cold domestic water enters the tank through the inlet pipe / and becomes warm by contact with the outside surface of the tube b, the hottest water being in the region near the top of the pipe g.
