Why We Run Steam Boilers At 2-PSIG Pressure
And hot-water boilers at 180° F.
When business gets wacky I like to settle down with some really old trade magazines and travel back to a time when business was even wackier.
I have a collection of The Metal Worker, a weekly trade journal that carried all the news, good and bad. I have every issue for 1899, which was important year in heating history, and a very wacky one. Many of the oddball devices that I’ve seen in basements over the years – the things that made me scratch my head in wonder – appeared as new product introductions in that wonderful magazine during that fin de siècle year. Reading through those 52 issues is like getting into a time machine. And there’s a certain peace in that. There’s no uncertainty in the past.
This was the year of The Carbon Club, an association of boiler manufacturers who got together in the spirit of what they called “cooperative competition,” a concept that would send you to slammer if you tried it with your fellow wholesalers nowadays. But The Carbon Club guys were brazen in their very successful efforts to control not only the price but also the supply of boilers. They did it for what they saw as the good of the industry, and because cast iron was scarce that year, oh, and because they wanted to make large profits. They also did it in spite of the Sherman Antitrust Act, which had been the law of the land for a decade. These guys defined wacky.
Here’s a brief article from The Metal Worker, which appeared on July 15, 1899. Listen:
“A meeting of the Carbon Club will be held in New York on next Monday, when the reports of the Membership Committees will be made. While the desirability of securing all manufacturers as members is apparent the condition of the iron market and the outlook is more important. The minimum price schedule adopted on June 20 has been found to contain some defects, and while these will be open for correction it is probably also that a further advance will be made in the list. This, if done, will be due to the price and scarcity of iron, with the strong probability that the price of iron has not yet reached the top. Some manufacturers, both outside of the club and members, have arranged for their iron supply for the year, but as it could not be replaced except at the market prices, the price of boilers should be arranged in accordance or a radical advance would be necessary in boiler prices made by any manufacturer when his iron supply was exhausted and must be replaced at the much higher cost. This has been clearly pointed out, yet there are manufacturers who are holding to the former low prices, preferring to selfishly reap whatever benefit can be derived from being on the outside rather than to do their share to build up the market on a sound business basis. Should their example be generally followed demoralization and a year without a profit would result. Sometimes severe measures are necessary to open the eyes of the selfish. The Carbon Club is now strong enough to seek out the customers of such manufacturers and apportion them to the members with the instruction that prices must be quoted to them low enough to secure their trade. This would be drastic and not without its drawbacks, and it is to be hoped that cooperation can be secured by a more commendable method. Some members of the Carbon Club who were formally regarded as price cutters frankly state that though they suffered at the first advances they have now benefited by adhering to the course pursued and feel sure that others can be equally benefited by adopting the same course, whether members of the club or on the outside. The club, as far as can be learned, has been perfectly reasonable in all of its actions, and no considerable objection has been offered by the contracting trade.”
Isn’t that delicious? You’re a selfish manufacturer if you lower your price to get business, and if you persist in that wackiness of trying to get more customers by dropping your price, the entire membership of The Carbon Club will seek out your customers and steal them from you by basically giving away the stuff and driving you out of business. So there.
The selfish quickly got into line, and as I think about it, I realize that this was the boost the fledgling heating industry probably needed at the time. A very nice profit was guaranteed all manufacturers, and the contractors went along with it. The building owners paid their price and hydronics was born. All boats rose with the tide, which they forced, but who knows how it would have gone if The Carbon Club hadn’t broken the law.
This is the other thing that The Carbon Club did that year, and this forever changed the way we size heating systems. They waited until the very end of the century for this, and it makes me smile every time I read it. Here you go. This was in the December 23, 1899 issue of The Metal Worker:
“A meeting was held of the Carbon Club at the Murray Hill Hotel, New York, December 18 and 19, with a large attendance of the members. Several applications were received from manufacturers and some new members were elected. The recommendations of the Committee of Boiler Ratings, which were discussed at the November meeting, were taken up, and after some minor changes, were adopted. This is virtually a standardization of the home heating boilers made by the members of the club, and with the uniform rating and uniform prices many of the perplexities of the trade are removed. All boilers are now rated on a proportion of 100 for steam and 165 for water, with steam at 2 pounds pressure or water at 180 degrees at the boiler. The rating now includes all mains, returns and risers as heating surface, and the surface exposed in them must be added to the surface required in the radiators to determine the boiler power needed. It is only necessary for the trade to understand that the mains must be considered to avoid purchasing a boiler that is too small. If a boiler show the 2 pounds steam pressure or 180 degrees temperature in the main when at work, the rating will be considered verified by the manufacturers. The new list also divides boilers into two classes. A uniform rating has been agreed upon for tank heaters on a basis that they will heat 130 gallons of water for every 100 feet of surface that they are rated to carry, and their prices have been rearranged so that concessions are made to the buyer on some sizes.”
What we have here is the agreement between all the boiler manufacturers of the time that a hot water boiler should be 65% greater in capacity than a steam boiler serving the same building. You see that today when you look at the difference in the value of Equivalent Direct Radiation for steam and hot water radiators (240 Btuh per Sq. Ft. EDR for steam and 150 for hot water).
They also agreed that no steam heating system from that day forward should need more than 2-psi pressure at the boiler to heat the building. This was a very significant decision because it put a stop to what was becoming a very dangerous situation. Contractors had been using boiler pressure as a competitive edge. They were sizing systems with as much as 60-psi pressure at the radiators. Higher pressure means smaller radiators and pipes, but the problem is, all steam-heating systems have to start at 0-psi pressure, and at the lower pressure, the steam would suck the water out of the boiler. This caused boilers to either dry-fire or explode. The Carbon Club put a stop to that wackiness. They did it by standardizing pipe-sizing charts that would allow for a one-ounce of pressure drop over 100 feet of travel. They leveled the playing field for the contractors.
At that meeting, they also recognized that there is a piping pick-up factor, which must be recognized by contractors when they size a boiler, lest they undersize a boiler, which would be very bad for the manufacturers. They established a standard for heating domestic hot water, And finally, they let the proof be in the pudding. If a contractor could heat the entire building with a boiler that contains no more than 2-psi pressure, or 180° hot water, then he picked the right boiler for the job. If it couldn’t do that, then the problem was on him.
Maybe those days weren’t as wacky as I thought they were.