9i 



JOUKNAL OF HOBTICULTUEK AND COTTAGE GABDENER. 



[ Jamiaiy 29, 1874. 



the higliest poiut of the apparatus in every instance; those on 

 any level but the highest, by which the air is to escape in 

 lining the circulating medium, should be closed when the hot- 

 water pipes are full. The taps may need to be opened occa- 

 sionally to let out any accumulated air, but only so long as 

 to allow of the space thus freed of air being tilled with water. 

 These pipes, with taps to let out the air, are objected to 

 by most persons who construct apparatus for heating by hot 

 water, but to what the objection is taken I cannot make out, 

 as the heating in such cases is quite as satisfactory as when 

 the air pipe is open. Note. — I am here alluding to heating 

 houses on difierent levels. On the lower levels I say taps are 

 good, or better than any number of feet of open-air pipe ; but 

 on the higher levels air pipes of some length are necessary, 

 and it is well if the circulating medium is not quite filled with 

 water, but so much so as to allow of the circulation of the 

 water. This affords space for the expansion of the water as 

 heated. Either we must allow space for the expansion of the 

 water or have air pipes communicating with the external air, 

 and such I have had frozen-up in severe weather, and com- 

 pletely useless. 



The supply cistern will need to be fixed at such a level as 

 not to fill the pipes on the highest level more than three parts 

 full of water ; or if so high as to fill them the air pipes must 

 be taken up higher than the supply cistern, and their ends 

 communicate with the external air (which, for reasons already 

 given, I do not advise) to allow of the water passing out of 

 them, as it will when the boiler is hard driven or the swell of 

 the heated water greater than the pipes can contain. The 

 pipe from the supply cistern should enter the boiler at its 

 lowest poiut, or the return pipe by a syphon, which, whilst 

 it will admit of the cold water from the supply cistern being 

 drawn into the boiler, will prevent hot water flowing up it. 

 But a better plan is to have a self-acting valve at the mouth of 



the supply pipe in the supply cistern, which will be drawn up 



by the suction of the water when the boiler is feeding, and 



closed when the pressure of the water is from the boiler into 



the feeding cistern, and which occurs when the pipes are filled 



to the level of the water in the cistern and pipes alike, as it 



only is in this ease when the water is not heated. Water will 



always find its level : when it is hot it will fill more space 



t than when it is cold, and it must expand into the air pipes, 



and bo driven out of them when boiling, so wasting water, or 



fill the supply cistern to overfiowing, or space in the highest level 



of the pipes must be left to allow for the swelling of the water. 



No hot water ought to work up the supply pipe, and that it is 



prevented from doing by a self-acting valve as above described. 



I If the houses are on different levels it may happen that 



i those on the lower level have to be heated whilst the higher 



. ones are not heated, the latter being shut off. The air pipes 



; and space left for the expansion of the water are of no use to 



j the lower levels in this case, but the water will expand all the 



same. To meet this I would have an air pipe on the main 



from the boiler, which would allow for any expansion and 



boiling-out, and its end might terminate in a gutter or drop- 



I spout, only I would have it not exposed to frost. With a pipe 



of this kind air pipes may be dispensed with, only we must 



have taps at the highest parts on all the levels, to allow of fill- 



j ing the pipes with water, and to let out any air that may accu- 



! mulate. Water being driven out of the air pipes in houses in 



1 winter or at any time is a great nuisance and source of evil. 



I fear I have made this matter of air pipes, swell of the water, 



and boiling very complex, but I will endeavour to render my 



meaning clearer by a diagram ; but I would just say that the 



supply cistern and pipe must be out of the reach of frost, and 



that it need not be larger than 18 inches long, 7J inches wide, 



and 12 inches deep, and the supply to it should be regulated 



j by a ball-cock. 



In the above section it will be seen that the compartments 

 heated are ou six different levels. In describing them let us 

 begin at a, the flow from the boiler, which, it need hardly be 

 stated, is lower than any of the flow pipes, b Is the return pipe 

 to the boiler, entering it at its lowest part. The flow pipes 

 throughout their length rise about half an inch in 12 feet, 

 which is independent of the lise consequent on the levels ; and 

 the return pipes have the same fall to the boiler as the flow 

 pipes have a rise from it, the return pipes being taken directly 

 under the flow pipes. The direction of the water is intended 

 to be shown by the arrows. 



c Is a Mushroom house heated by a flow-and-return 4-inch 

 pipe, a, b, on the same level as the main flow-and-return pipe, 

 and having an air pipe c. This air pipe serves the whole of 

 the apparatus as a swell and blow pipe now, but not when it 

 was its original length ; for when it was the same length as 

 the other air pipes the water was thrown out first at one and 

 then at another, causing quite a nuisance from the hot water 

 dripping and the damp generated. To put an end to this, and 

 have all the boiling or sweU-out at one point, the air pipe was 

 shortened to d — about 2 feet, and its end so contrived that 

 the water would drip into a down or drop spout in connection 

 with a drain. From that day to this, or about three years, 

 there has not been any water thrown out of any of the pipes 

 but this at (/. Even when the heat is not wanted in the Mush- 

 room Louse the water in the whole of the apparatus finds its 

 level through the valve on the return pipe being left open, so 

 as to allow of any swell being parted with through this air 

 pipe. It answers, therefore, the purposes of air pipe for the 

 Mushroom-house pipes, and as blow pipe as well for the whole 

 apparatus. 



D, Fernery heated by a flow e, and return 4-inch pipe /, on 

 the same level as the main flow and return pipes, the pipes 

 being one over the other, and with an air pipe at the highest 

 point g. 



E, Peach house heated by two rows of 4-inch pipes on the 

 same level, but 2 feet above the main flow pipe, and rising 

 to /( where is a tap (at present a plug) to let out the air when 

 filling the pipes, or any that may accumulate, it being occa- 

 sionally opened for that purpose, and closed when water comes 

 out. This, though having no air pipe always open, heats very 

 quickly. 



F, Peach house heated by three rows of 4-inch pipes on the 

 same level as the other Peach house, or 2 feet above the main 

 flow-and-return pipes, the pipes being all flows, there being an 

 open air pipe /. The heating of this house is not so good as 

 any of the others. 



G, Stove heated by four rows of 4-inch pipes all round except 

 the doorway, the four rows being 3 feet higher than the main 

 flow-and-return pipes, and having air pipes at their highest 

 points, J j. There are also pipes for bottom heat to the centre 

 bed, these pipes being 1 foot 6 inches above the main flow-and- 

 return pipes, and having a short air pipe k coming through the 

 bed, with tap on its end. The heating of this house is very 

 good, especiaUy the pipe beneath the bed, and with the closed 

 air pipe. 



n. Pit heated by two flow 4-inch pipes for top heat, and 

 returns for bottom heat to the bed. The pipes are on a level 

 2 feet above the highest pipes of the stove, and their highest 

 point is at I, where there is a tap to let out any air, which does 

 not need to be done onco in six months. 



I, Pit heated by two 4-inch pipes one above the other, and 



