CHAPTER XXII 



HOT WATER HEATING 



THE improvements in this method of heating have been 

 so great during the past few years that this system 

 is worthy of careful consideration. The advantages of hot 

 water over steam heating are stated by those who favor this 

 method to be as follows: Economical operation, even heat, 

 perfect control, absolute safety, and that it can be operated 

 with low fires and will maintain an even and steady tempera- 

 ture with less attention than steam. 



Hot water is now being used extensively as a medium of 

 heating greenhouses for all kinds of crops, and, of late years, 

 many large Rose establishments are being heated in this man- 

 ner. When used for Rose growing, it should be arranged in 

 small units of radiation, and at this time it is the practice to 

 control each and every return line by independent gate valves. 

 With gravity circulation you can heat coils up to 250 feet 

 in length ; with forced circulation there is no limit to the 

 length of houses or size of the plant to be heated by hot water. 



Any size of pipe may be used, but the ideal piping systems of 

 today are 2-in. and 4-in., and large flows with 2-in. returns. 

 The following sizes of piping can be employed, if desired: 

 For houses up to 100 feet in length, 1^4 -in. returns; for houses 

 up to 150 feet in length, 1^-in., and up to 250 feet in length, 

 2-in. returns. 



With hot water heating you require an open expansion tank 

 for a gravity system, and for a system to work under pressure, 

 a good sized closed tank, elevated several feet higher than the 

 highest point of the system, and so located as to make direct 

 connection with the main return near the boiler. 



