This section is from the book "American Plumbing Practice", by The Engineering Record. Also available from Amazon: Plumbing: A working manual of American plumbing practice.
George B. Hayes, Buffalo, N. Y., writes: "Noticing your sketch in issue of August 8, 1891, called 'A Kitchen and Laundry Boiler System,' I am induced to ask if you have ever published a description of a perfect interchangeable system of hot and cold water for kitchen and laundry with a boiler in each."
[On page 153 of "Plumbing and House Drainage Problems" reprinted from The Engineering RECORD, and published at this office, is an illustration showing how to secure circulation between boilers in different houses. A modification of this can be applied to the case cited. We cannot call to mind a recent interchangeable system that appeared in our columns, but we can see no reason why an apparatus arranged as per sketch will not do when one boiler is over the other.
INTER CHANGEABLE HOT AND COLD WATER SYSTEM.
A is the kitchen boiler, arranged in the ordinary manner, and B is the laundry boiler. When the cock a is closed the upper apparatus may be run past as though the lower one was not in existence, as no water will circulate in or out of the lower boiler and cannot flow from the lower boiler into the upper pipe, for the simple reason that a is closed. In like manner, when b is closed and the lower boiler only is in use, the boiler A is inert. Of course when the two fires are in operation the two boilers may be run together by having cocks a and b both open.]