Calling Dan Holohan
If any of you really want to know about Steam heat and how to make it work properly, pick yourselves up a copy of "The Lost Art of Steam Heating" by Dan Holohan.
He is the most knowledgeable man there is on the subject. You can find him easily on the web.
And he is also an expert on Hydronic systems as well. Amzing some of the things we do with those systems and the all too common mistakes we make and the misconceptions we have concerning steam and Hydronic Heating!
What follows here is strictly for a single pipe steam system. One which has only on pipe through which the steam goes out from the boiler to the radiators in each room. The condensate from them returns to the boiler thru the same pipe. If you have a 2 pipe system, there is a whole other set of rules and standards that apply. You can read more about all of this in Dan's book.
But here is one thing you should all know and I proved it in my own home when we were up there.
Most people will run their steam systems at pressures which are too great for a home system. There is absolutely NO need to run it at a pressure setting above 1 PSI! I know you are all going to say that is wrong but a properlysdesigned steam system at 2 lbs would send stream up to the top of a 4 story building.
The air valves are necessary on each radiator in order to let the air out of the radiator or convector because one pipe steam systems are open to the atmosphere and the air must be displaced so that the steam can get to the radiators. So you would want a very fast venting valve at the end of each main run from the boiler and then you can size the individual valves according to how far they are from the boiler so that all the rooms would get heated up at approximately the same time. It takes time and patience to properly balance a system in a house.But it is well worth the effort.
The problem arises when the pressure in the system exceeds the specifications of the air valves. Namely, the valve lets the air out and when the steam enters the valve, the innards of the valve expand and close off the exit at the top or side of the valve. The valve will then "cycle" open and closed as the valve cools to let the air back out of the radiator and allow more steam into it. The process repeats itself during the on cycle of the boiler. We all know how cozy that sound can be and know when we don't hear the clicking of the valves on and off, we know something is wrong.
The specification of the valve will tell you what the "drop down" (for lack of better word and not the term Dan uses)spec of the valve is. That means that the valve will open and close when there is no more than so much pressure exerted against the inner mechanism. If the pressure is too great for the valve to overcome, the steam pressure pushing against it will keep it closed even though the valve has cooled sufficiently that it would be calling for more heat. This then results in the radiator not getting hot enough or actually going cold.
What would be your natural reaction or the plumber who is not in the know's reaction? Simple..we need more pressure! So up goes the Pressuretrol on the boiler and to no avail and maybe even more radiatoors star getting cold.
Dan recommends the removal of the pressuretrol and installing a VAPOROSTAT. That measures pressure in ounces not pounds.
He suggests no more than 14 ounces on the cutout. It seems too low, but you will all be amazed at how well all those air valves will work at that setting. You might even hear some clicking on and off that you never heard before and you will even out the heat throughout the house.
It is very difficult to get a pressure control which would allow you to adjust the cut out pressure to no more than one pound and let you get a cut in of maybe 1/2 lb. They just aren not designed to do it. some are additive and will cut of at an even higher pressure than you may set it at. That is why the vaporostat is the way to go.
I was amazed at the difference in how our system worked after I changed out the pressuretrol. No more overheated rooms and much more uniform temps all around.
What happens when you increase the pressure. you wind up burning more fuel and still have a cold house. The boiler runs longer cycles to satisfy the pressuretrol and the thermostat is left waiting to be satisfied because you cannot get the steam out into the radiators.
At today's prices for fuel, you could be spending loads and still feel cold!
Someone mentioned changing out the radiators for baseboard heat.I think we have all done that, but the reality of it is is that while they seem to heat up really fast and warm up the room quickly, there is no residual heat left in them when the system shuts down like a cast iron radiator has. They look good and in some instances, the baseboards are the best for a specific decorating situation, but they really are best suited for hot water hydronic systems and sometimes no matter how many feet you install, with steam, you may not get as many btu's as you would actually need for a given room size.
The old timers who sized up your radiators did use some sophistcated methods in determining how much radiation was needed for each room.
As far as noise and banging, the solution above to the convectors'noises was correct, they do need to pitch back down to the supply side and that goes for the goold old radiators as well as the condensate needs to go back to the boiler at a temperature warm enough to preven the hot incoming steam from encountering cool enough water to creat the hammering you hear in the pipe. Water Hammer can be very destructive to a heating system, just as it can be in a water supply system, though caused by other things.
If you have air valves which are constantly hissing and letting steam escape into the room, they need to be replaced because they are letting the water from the boiler evaporate into the house and allowing perhaps too much moisture into the room which can cause damage to wals, paint, wallpaper etc, not to mention it can lead to mold and mildew inder the right circumstances. And, let's face it, boiler water doesn't really smell all that good either.
You can clean the valves and perhaps buy more time out of them by immersing them in vinegar or descaling solution and then rinsing them out BEFORE putting them back into operation. If they still don't work properly, just replace them.
A good plumbing supply house should carry Gorton Valves and other brands as well. Price does equate to quality so try to stay away from the ones that cost 3 or 4 dollars. They may work for a few months if you are lucky. The supply house should be able to provide you with literature on the proper valve for each room.
I hope this helps
