-':T:''"<w!™r''-'^"'T^rr'''''"''^~"r:w^~''wwTwwwFrw»'^^ 



■fimiiiripp^pi mimmff^fmmmn'^'^ 



1424 



The Weekly Florists^ Review* 



March '21, 1907. 



Greenhouse Beating. 



HOT WATER HEATING. 



For four years I have read the Review 

 and noted carefully the articles on hot 

 water heating, by L. C. C. In the main 

 I agree with him, but not always. 



I believe that all will agree that a hot 

 water boiler should be so constructed as 

 to contain the minimum amount of water, 

 with the maximum amount of heating 

 surface. By this means we more nearly 

 approach steam as to quickness of heat- 

 ing. While much of the efficiency of the 

 boiler depends- on the firing and the way 

 it is handled, upon which much could be 

 said, it is about the circulation that I 

 wish to write. We all know that if the 

 pipes fail to heat, they fail of their pur- 

 pose; and, too, the full benefit of the 

 fuel consumed is not obtained. ' Therefore 

 with poor circulation we fail to secure 

 the full efficiency of the boiler. 



In piping, I believe there is no differ- 

 ence whether the highest point in the 

 system is directly above the boiler, or at 

 the far end of, the houses. I would govern 

 this by existing conditions. If the val- 

 leys of the greenhouses slope toward the 

 boiler, then the flow pipes can parallel 

 the purlins, which would afford the nec- 

 essary rise to the far end of the houses. 

 If the\alleys slope from the boiler, the 

 highest point should be above the boiler, 

 in which case the flows can again paral- 

 lel the purlins, affording the proper fall 



times the capacity of the flow, then the 

 water in the flow pipe must move three 

 times as fast as in the returns, if circu- 

 lation is even. One can easily see that, 

 with this proportion, a slight cause, such 

 as a sag in some of the pipes, would in- 

 duce the water to take to the returns 

 unevenly. Where the returns are six 

 times the capacity of the flow this ten- 

 dency would be greatly increased. 



While the force of expansion in heated 

 water is strong, yet, like all forces, it 

 follows the least resistance. This is a 

 simple fact, but often unheeded in in- 

 stalling a system. The placing of the 

 manifolds is a fruitful source of bad 

 circulation. I can best illustrate this 

 point by sketches, as shown below: 



It will be seen at a glance that the 

 manifolds in figures 1 and 2 are alike 

 and also in figures 3 and 4, the differ- 

 ence in the radiator being in the re- 

 versed manifolds. In figures 1 and 3 

 the water has a short, medium and long 

 cut and, if it has its own way, as it 

 surely has, it will take the short cut 

 with greater velocity and thus the cir- 

 culation is impeded. In figures 2 and 

 4 there are no short or long cuts, the dis- 

 tances through each pipe being exactly 

 the same. In this case, other things 

 being equal, the circulation will be per- 

 fect. 



Figure 5 is a common form of mani- 

 fold and is all wrong and no amount of 

 reversing can make it right, except to 

 reverse it into the junk pile. 



This placing of the manifolds is cer-w 



house were 100 feet the flow would still 

 have capacity to supply 1,200 square feet 

 of radiation, which, if supplied in 3-inch 

 pipes, would mean twelve 3 -inch returns 

 in th^ house. So you see it is impossible 

 to base the relation between flow and re- 

 turns on size and number of pipes aloue. 

 The only just and safe way is as above 

 described. Because builders and plumb- 

 ers do not give these matters due weight, 

 I believe it is safe to say that ninety 

 per cent of the greenhouse plants are 

 piped without regard to capacities, and 

 at a consequent loss, because of undue 

 outlay for pipes which bear no relation 

 to the work to be done. L. C. C. 



PIPE FOR ONE GREENHOUSE. 



I am erecting a new even-span north 

 and south house, 16x50. The sides are 

 three feet nine inches high, double 

 matched boards with sheathing paper be- 

 tween; ridge, seven and one-half feet 

 high, no glass in the ends. Will you 

 please give the amount of pipe needed 

 and size of the returns and flows, to 

 maintain a temperature of 50 degrees 

 to 55 degrees in zero weather? Also, 

 where should be the highest point in the 

 system? I have a 3x10 horizontal brick- 

 set boiler with thirty tubes three inches 

 in diameter. Please give amount of radi- 

 ation the boiler will carry. G. H. W. 



The house in question can be heated 

 by using ten runs of 2-inch pipe or by 

 thirteen runs of 1%-inch pipe. If you 

 wish to keep all pipes under the benches 



4- 



V\g. 1. 



Flgr. 2. 



Fir. 8. 



Flir. t. 



Fig. 5. 



J — c 



' ' ' ■ ' ' ' ■ c 





izr 



■"^ 



J— c; 



■^ 



Figures 3 and 4 are the Coils in Which Inlet and Outlet are Properly Placed. 



back to the far end and down to the re- 

 turns. 



Each house should have its own sys- 

 tem from and to the boiler. This is ab- 

 solutely necessary. The flow pipe may 

 be branched on entering the house, each 

 paralleling the purlins or under the 

 ridge and branched at the far end. The 

 expansion tank should be directly above 

 the boiler and preferably enter the boiler 

 at one of the returns. It should be 

 slightly higher than the highest point in 

 the system. There should be an air-vent 

 in each flow pipe at its highest point. 

 This may be a small air-cock, which 

 should be opened at least once a day, 

 in severe weather, to allow air to escape; 

 or, it may be in the form of small pipes 

 extending slightly higher than the top of 

 the expansion tank, in which case they 

 may be left open. 



As to comparative capacity of flows 

 and returns, that is where I think L. C. 

 C. is in error. In no case would I ad- 

 vise (if for myself, allow) the returns 

 to be more than three times the capacity 

 of the flow. L. C. C, in one case, ad- 

 vised a 3-inch flow and six 3-inch re- 

 turns. In the February 21 issue of the 

 Eeview he advises W. E. D. to use a 

 3^ -inch flow and seventeen 2-inch re- 

 turns, which is almost the same propor- 

 tion. 



It is clear that if the returns are three 



tainly a simple, plain proposition, and 

 yet, when down under a bench, the 

 wrong way may be much the easier to 

 install. The easier way will invariably 

 be taken by those who have not the suc- 

 cess of the system at stake. 



Then it is important that the returns 

 from the radiators to the boiler be exact- 

 ly the same as the flow from the boiler 

 to radiators. Any other plan will im- 

 pede circulation. For a house 25x100 

 the flow from the boiler should be 5-inch, 

 which may be divided in the house as in 

 above outline. The return radiators 

 should be connected to a 5-inch pipe into 

 the boiler. I am aware that this will be 

 considered expensive by some. But after 

 all, is it not the results, the satisfaction, 

 the real fuel economy, that should in all 

 cases be considered? I firmly believe 

 that my system thus installed has saved 

 me in two years at least $100 in fuel. 



S. C. Templin. 



The relation which exists between 

 flows and returns in heating pipes can- 

 not be determined by the number of 

 pipes. The relation is that capacity to 

 furnish a determined amount of radia- 

 tion. To illustrate: A 3%-inch riser 

 has capacity to supply 1,200 square feet 

 of radiating surface. This would be 

 equivalent to three 3-inch pipes, each 

 400 feet long, but if the length of the 



you can divide the ten 2-inch pipes as 

 follows: Two 2-inch flows each supply- 

 ing four 2-inch returns. I prefer to have 

 the highest point in the hot water flow 

 at the most distant point in the system. 

 ^ Your 3x10 boiler is probably rated at 

 eighteen or twenty horse-power and 

 should be capable of supplying heat for 

 about 2,350 square feet of radiating sur- 

 face. L. C. C. 



CAPAQTY OF BOILER. 



We have one house, 14x70, set three 

 feet in the ground, so that the gutter 

 is slightly above the ground and six 

 feet from the gutter line to the ridge. 

 We have a No. 3 Boynton hot water 

 heater, outside the greenhouse, set so 

 that the top of the heater is slightly 

 below the level of the greenhouse floor. 

 We have one 3-inch flow running under 

 the ridge and returning through twelve 

 1%-inch returns, six on each side of the 

 house, which heats it easily. Now, we 

 want to build another house and leave 

 the two houses disconnected for one win- 

 ter, the new house to be 20x90 ard six 

 feet to the gutter line, with good side 

 walls; but we want three feet of glass 

 from the gutter line down on the south 

 side. Will the heater carry both houses 

 at carnation temperature when it is 20 

 degrees below zero outdoors? If not, 

 what length of the large house will it 



