29 



in many plants giving good satisfaction. Here again the steam pump may be 

 used to draw back the condensation but the steam trap is more effective and is 

 less liable to get out of repair. 



The other system of steam heating used in greenhouses to some extent is 

 known as the high pressure system and is where over ten pounds of pressure 

 is carried at the boiler, reducing it as desired for the houses and bringing the 

 condensation back by means of steam traps or pumps. This system should only 

 be attempted on large ranges and then installed by men competent to do so. 



A vacuum system of heating is being installed in some plants and works on 

 the principle of high pressure at the boiler and by the use of reducing valves and 

 vacuum pumps the steam passes through the coils in the houses at atmospheric 

 pressure or under. This form of heating for large plants is recommended as the 

 most economical now, but must be properly installed by competent men to be 

 worked successfully. 



ADVICE TO PEOSPECTTVE BUILDERS. 



(1) All construction companies keep a staff of men whose business it is to 

 give all information in regard to their forms of construction. They are there for 

 the builders' benefit. 



(2) Find out all about the different makes before making your selection. 



(3) Do not give an order for material until you are satisfied it is exactly what 

 you require. 



(4) If in doubt ask or write some grower who will give you an unbiased 

 opinion and knows whereof he speaks. 



(5) Successful growers follow the rules "the best is none too good" and "a 

 poor thing is dear at any price." 



(6) Construction companies are used to building large ranges and will give 

 you the benefit of their experience in regard to location, site, etc. 



(7) Insist that all the accessories such as nails, ventilating apparatus, putt}'', 

 paint, etc., be of first class and that they are properly used. 



