Hot water is unquestionably the best system for heating small houses, and there are many arguments in its favor for large ranges of houses. If pumps or a pressure system are used to secure rapid circulation, the radiating surface need not be much greater than in a steam system. The higher cost of installation has always been one of the greatest objections to hot water. With the pressure system instead of the open tank, the water is heated to a higher temperature and also made to circulate more rapidly.

The advantages of hot water over steam may be stated as follows: (1) As the hot water in the pipes retains heat for a greater length of time, the boiler may be left for a longer time without attention. This is a great advantage in small greenhouses, where it would not pay to employ a night fireman. (2) Less fuel is consumed. (3) Proper conditions of moisture are maintained with less difficulty. Other advantages are often stated, but the foregoing are the most important. It is not so expensive, however, to install a steam plant nor so troublesome to make repairs.