Glasshouse Building 227 



the surface, and then it can be carried the rest of the way at a depth 

 of 18 in. As long as a fall of 6 in. per 100 ft. is allowed, the drain can 

 be reduced in depth as soon as possible. The stokehole must be made 

 deep enough for the flow pipes to be taken off the boiler easily. In 

 this connection a lot of room may be saved if the boiler is fitted with 

 a short bent flow socket. If more than one house is to be run from the 

 same boiler, screw-down valves must be provided on the flows and re- 

 turns in each house. All exposed pipes round the boiler and leading to 

 the houses should be coated with asbestos cement, and the pipes from 

 the boiler to the houses are much better boxed right in with brickwork 

 or concrete. A serious amount of heat will be wasted unless this is 

 done. The back rows of pipes can be slung from the plate by iron hooks 

 fixed to the plate with a 2-in.-by-J-in. coach screw. If these hooks are 

 made all the same length, and the proper fall has been given to the house 

 walls, the pipes can be set with the greatest ease. For greater security 

 it is best to have the pipe hooks bent over at the top so as to fit the 

 plate, and thus give the coach screw assistance in bearing the weight 

 of the pipes. The front rows of pipes are slung from the purlin standards 

 or placed on brick or concrete piers. These are very simply made with 

 concrete as follows: Holes about one spit deep and 1 ft. square are dug 

 out in a line up the house, where the pipes are to come; pegs are 

 set up in the middle of the holes and the correct rise given to them 

 in the same way as to the pegs used when giving the rise to the walls; 

 2 or 3 in. of concrete is put over the bottom of the holes and then a 

 little framework of any odd bits of rough wood is put round each peg 

 so as to leave space for the pier to be made 5 in. square. The concrete 

 is now filled in up to the top of the pegs and the piers will be ready as 

 soon as they have set. When the pipes are put on the top they should 

 be bedded in cement mortar. The pipes are put together with cement 

 joints made as follows: The pipes are slipped into each other, then about 

 two strands of pipe yarn are twisted up and driven into the joint with 

 a caulking tool till the end of the joint is reached. Pipe yarn as bought 

 consists of four strands twisted, but this is too thick to be driven in. 

 Three strands are now twisted up and just tucked in all round the joint, 

 leaving a little hole at the top. Make a little cup with the loose ends 

 of yarn and pour into the space between the two rings of yarn cement 

 mixed to a thick cream till no more can be got in. Tuck in the loose 

 ends and drive the yarn in as far as possible. The next day the joint 

 can be faced up with neat cement made into a stiff mortar. Nothing 

 .short of a red heat will loosen such a joint, and they will stand all 

 ordinary pressures without leaking; a few drops may ooze through when 

 the pipes are first filled, but this will generally stop in a short time; if 

 not, the facing must be chipped off, and, if possible, some of the yarn 

 scraped out and the joint refilled with cement mortar as before. Hot- 

 water pipes can easily be cut with a sharp cold-chisel to whatever length 

 is required. The chisel should be given a point with a rather wider 



