38 BULLETIN 894, U. S. DEPARTMENT OF AGRICULTURE. 
An overflow to sewer of capacity of the return water drain should be 
placed near the inflow. A steam syphon or pump in place of natural 
drainage to sewer should not be used. Some means should be pro- 
vided for emptying the well for cleaning, either by a valve d drain 
when the bottom of the well is above the sewer, or by a steam syphon 
or pump. 
A cold-water supply should be brought to the well and connected 
through a float valve to supply any deficiency and to maintain the 
constant water level at all times. 
HOT WELL. 
In some installations two wells are used: One for recirculating 
water and one for hot water. A hot well is needed where high tem- 
perature runs are to be made. In such cases the returning spray 
water is not hot enough to maintain the desired humidity. 
Where the need of hot water would only occur occasionally — that is, 
where high temperature runs are the exception rather than the rule — 
is is undoubtedly more economical to use the steam jet as indicated 
under " Water supply" to raise the temperature of the water at the 
sprays to the desired temperature than to resort to the use of the hot 
well. Two wells are advisable, however, where a wide range of tem- 
perature is to be used on green stock. 
Where hot wells are used, three water mains are necessary — hot, 
tempered, and cold — and all are cross-connected at the water mixer. 
The temperature of the water in the hot well can be controlled 
thermostatically, where necessary, by installing a self -controlled or 
air-controlled thermostatic valve, having the control bulb in the 
well and the valve on a high pressure steam supply opening into the 
well. 
Where convenient the full or partial condensation from the coils 
may be turned into the hot well after passing through an oil strainer. 
HOT WATER TANK. 
Another method of supplying the necessary hot water is to take a 
branch off the recirculating main to a closed steel tank where it is 
heated by heating coils. From the tank the hot water is carried 
to the kiln by a hot-water main, as described heretofore. This 
does away with the need of a hot-water pump, as the recirculating 
pump furnishes the pressure for both recirculating and hot-water 
supplies. 
The tank should have a capacity of from one-fourth to one-third 
that of the recirculating well, depending upon the amount of hot 
water needed. 
The heating coils in the tank must be supplied with high pressure 
steam to raise the temperature of the water to 185 or 190 degrees. 
