December 31, 1OT4. 1 JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 



581 



WEEKLY CALENDAR. 



MISTAKES ABOUT HOT-WATEB 

 ARRANGEMENTS. 



h^^F AID .a brother horticnlturi.'^t, " How I envy 

 you your beautiful forciug houses, so well 

 built, so light, with abundance of hot-water 

 pipe.=i for both top and bottom heat, with 

 screw valves on flows and returns, and such 

 a clever system of ventilation too ! Any- 

 body could grow plants in such bouses 

 as these. You have only to make your 

 wishes known as regards temperature in 

 each division, and by the turn of a screw 

 it can be bad to half a degree." Yes, they are nice 

 houses, with plenty of piping, plenty of valves ; they 

 are cleverly ventilated, and have many other good 

 points, but they also have two or three serious defects, 

 which I wish to make public for the benefit of other 

 people who may contemplate building or heating such 

 structures. 



Well, then, as to heating. I believe my friend ex- 

 pressed what is a very general opinion, that if you have 

 a good boiler, and plenty of piping, with valves for each 

 division, everything ought to work satisfactorily ; but in 

 practice we find that more depends on the aiTangement 

 of the heating apparatus than upon the shape of the 

 boiler or 10(1 feet more or less of piping. Hot-water 

 engineers will tell us they do not mind dips ; and if their 

 work and material are supplied by contract, you will pro- 

 bably have plenty of them, unless you insist at the first 

 outset, as I always mean to do whenever I have a voice 

 in the matter, not to have one whenever it can be avoided, 

 and it generally can by using a few feet extra piping. 

 "What I mean by a dip is when the pipe descends, as it 

 often does, to cross under a doorway or path and rises 

 again. Now, in about 120 yards I have eight such dips, 

 and there need not have been one. They do not dip 

 down to the level of the boiler, and for that reason are 

 not so bad as they might be. Started fairly on a summer 

 day with cold water in all the pipes they will work beau- 

 tifully, but whenever a severe frost comes they are sure 

 to be troublesome, and the circulation often stops sud- 

 denly on one or more divisions, and not .always on the 

 same. There is nothing efi'eotual then till the valves are 

 turned down in all the divisions which are heated, and 

 the water, if it flows at all, must of necessity flow through 

 the open ones. In addition to the dips the return pipes 

 inside the houses are placed higher than the flows, and 

 the consequence is that when the hot water in the boiler 

 is forced suddenly to displace some that is quite cold in 

 a portion of the pipes it often commences to do so at the 

 wrong end, although the main flow and return, which 

 are outside the houses, are fixed in the ordinary sinaple 

 way, one above the other. 



But why all these complications and antagonisms to 

 natural laws ? "Why drive a good servant to do work in 

 a roundabout unnatur.'il way when better results may be 

 obtairipd by mere gentle leading ? "We are so apt, in 

 matter,-: horticultural especially, as soon as we begin to 



No. 71S.-V0L. XXVII., New Seeies. 



know a little about Nature's workings, to fancy we can 

 do things in a much better way than that old dame 

 ever thought of. "We dismiss her without thanks, and 

 begin our work in a diametrically opposite way, but 

 after struggling on for a time, and meeting with many 

 failures, we are very glad to come back again to her 

 own sweet simple laws : hence we find elaborateness 

 and complications mostly with beginners. Simplicity and 

 an approach to perfection comes after a more extended 

 practice. 



But some may say, "What has Nature to do with cast- 

 iron pipes and screw valves ? It is not the pipes but their 

 contents. Nature has laws which regulate the move- 

 ments of fluids according to their specific gravity. If you 

 place warm water in the bottom of a vessel, and cold on 

 the top of it. Nature will not allow it to remam there, and 

 if by a lot of scheming you can possibly get the old 

 lady under your thumb, you will always find she has a 

 rebellious spirit ready to break out when a favourable 

 opportunity offers; tlierefore take her into your confi- 

 dence, acknowledge her indispensable aid, and all wUl 

 go well. 



There is a wrong idea prevalent, too, about valves, 

 many people think you can regulate the flow of hot water 

 in the same way as water that is not heated. So many 

 turns of a screw will admit so much water, and keep 

 house No. 1 say 15° lower than No. 2, while the arrange- 

 ments in both are exactly the same. It is not so. If the 

 valve is turned sufficiently for the water to flow at all 

 safely, there will be when the water is hot as much flow 

 through the half-opened valve as there wOl through 

 that which is wholly opened ; what is lost in volume will 

 be made up by increased velocity. Engineers know 

 and acknowledge this when they connect one series of 

 pipes with another by means of a single piece of very 

 small diameter : the small connection does not impede 

 the circulation in the least, it goes on just as fast as if the 

 large pipes had been continued throughout. "When a 

 number of houses are heated from the same boiler, and 

 some are required occasionally to be kept at a lower 

 temperature than the others, if they all contain the same 

 amount of piping there should be provision for prevent- 

 ing the heat circulating in a portion of the pipes, or there 

 will always be a difaculty in regulating the temperature. 

 In my own case, for instance, all may be left in perfect 

 order at eleven or twelve o'clock on a frosty night, but 

 by five or six in the morning the Primroses and^Cine- 

 rarias may be luxuriating in a temperature of 6.5°, and 

 the French Beans and Cucumbers at 40°. I am happy 

 to say I have only one specimen of this kind of heating ; 

 other three examples are extremely simple and ahnost 

 perfect. 



There are sometimes mistakes made in havmg the 

 main pipes too small where a large quantity of pipes are 

 heated from one boiler. We are too fond of 4-inch pipes ; 

 much fuel and labour would often be saved by having 

 mains 5 or « inches in diameter. I have known cases 

 where the water was boiling over, and yet the pipes 

 were not hot, simply, I believe, because the return 



No. 1870.— Vol- LIT., Olb Skhies. 



