This section is from the book "The Gardener's Monthly And Horticulturist V26", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The question of steam heating has been so thoroughly discussed in the Monthly that it seems like going over old ground to say anything more; but, under the heading of heating with common hot water pipe, I know will meet the views of many that would like to make the change, but, on account of the cost of the almost complete loss of the old hot water pipe, are deterred from trying steam. I will give as briefly as possible a very simple plan of how we have heated a large area of glass for the past two seasons, one of them very severe. We are using the old hot water 4-inch pipe, both the light 5 ft. lengths and the heavy 10 ft. as it was in the houses, with success, and, we are satisfied, much less cost of fuel than by hot water. The great trouble so far has been to get the condensed water back to the boilers without expensive check valves or pumps.
This is overcome by the laying of the pipe and the setting of the boiler or boilers, as it is safer to use two boilers on a large place than one, and when they need cleaning out in cold weather one can be in use and one idle. The first is the setting of the boiler and the size. It has been proven to quite a number that you cannot make steam in a tea-kettle (so to speak) to run a range of houses, which has been the reason of quite a number of failures of steam heating jobs. A boiler of sufficient size to hold steam more than just enough to fill the pipes is the only sure way of success. We have two boilers, bought second-hand, 26 ft. long, 50 inches in diameter, six flues each; either will heat the whole area, over 50,000 square feet; and with the cold 280 below zero, one did the work satisfactorily though both could have been used if needed, and at no time was there over 3 1/2 to 4 lbs. steam showing on the gauge. In fact at some of the distant points no actual pressure could be gotten but the vapor kept the pipes so warm that the hand could not be laid on them.
The quantity of pipe needed in houses is one-third that of water; that is, a house that takes six lines of 4-inch pipe to heat to 500 with the thermometer at zero, two lines of low steam will give even more.
Our plan is to set the boiler as far below the ground level of the houses as possible, without making it inconvenient, but sufficient to keep the water line in the boiler three to four feet below the lowest pipe on the return line. That amount of water will act as a perfect check valve to keep the water from backing out of the boiler which it will do if put on a level without expensive check valves and a steam pump, as inspirators will not work at low pressure. If it is impossible to get the boilers down low enough and the size of the place will justify it, a low pressure steam pump can be arranged on a sunken water tank that is steam tight, and pump the water back as it is returned by the condensed water pipe.
We start from the steam drum with two 4-inch pipes and take them up high enough so that the pipe continues to fall until it returns to the boilers, keeping them free of condensed water, and the water in them flows almost boiling hot ahead of the steam (or with it) making no noise or snapping of the pipes as where there is steam and water in same pipe. The mains or supply pipes at our place are all wrought iron, also all fittings around the boilers and the return line for the condensed water. We take the wrought lines over the tops of the doors in our sheds and drop down to the heating lines through the houses.
If wanted, a main supply can be taken to the far ends of the houses and the heating lines through the houses attached, but care must be taken to keep pipes all dropping to the boiler so as to have no traps to hold water, as it will make poor circulation in the line and liable to be broken by the passage of the steam through the water. In making the communications with the wrought pipe and the cast iron we have a fitting made for that purpose with socket on one end for the cast iron pipe and pipe thread cut on the other end. Our fitting is eighteen inches long and made of good cast iron, heavy enough to make it strong. All the lines through the houses must be suspended under the benches or on the walls, and one end of the pipe that crosses the houses, either flow or return, must be loose, so that the expansion and contraction will not pull the joints loose, or break the weak pipe. Our joints are made of iron borings, mixed with vinegar, to make them rust quickly. Water will do, but takes longer to rust. The joint made this way can be put up with less labor than hemp and red lead, and much easier to take out if wanted. In making the joint a small strand of hemp or oakum is put in first in the collar and the iron dust filled after, and well pounded.
Hemp joints will not do for steam on account of the expansion drawing them loose. The system we have been using has proved very satisfactory to us, and the cost is quite an item in the putting in of steam heating where all old pipe has to be taken out. From our experience, small boiler and small pipe, with strong pressure to force the steam, can only be a success where very large buildings are to be heated and not greenhouse work. Our plants have done quite as well, or better, than they did with hot water. And with plenty of furnace room to burn cheap coal, large flues and good chimneys, no trouble will be had with soot or dirt on the houses, or with the draft on cold nights, just when small boilers always choke up, if any thing but hard coal is used. Any style of a boiler that will burn soft coal or hard, tubular or horizontal, so that it will make steam enough to fill all the pipes and leave some to spare, will heat a large range of houses for two-thirds the cost of hot water, and the quick time with which the steam can be gotten over a large area will at once show to the florist and others that steam is bound to supersede hot water as a heating medium, but on large places only.
It will not pay a practical florist, with only small glass area, to use steam, unless he keeps night watch or goes to the expense of automatic drafts, etc., and the saving on a small place would not justify the extra care needed. Cincinnati, O.