So…we are moving one of our steam radiators two stud bays over. Which should be fine because, right now, the walls and ceilings are open and we can access everything.
The guy setting up our tile assured us he would do it for us. (Okay, one less contractor to call in.) He has subcontracted the plumbing work to a crackerjack plumber…I really admire this guy’s work so far.
But today. Today, when he was leaving, I asked him about moving the radiators. He let me know when he was planning on doing it. And then he mentioned that he will not be using the existing pipe (which is 90 years old, but totally fine.)
He wants to use a “new” kind of pipe. It’s insulated on the outside, made of steel (not iron) and is more “flexible”.
I am cautious by nature. “Have you used that kind of pipe with steam?” I asked. Because, you know, steam goes up, condensation rolls back to the boiler all in one pipe and the angle and flow are like tuning a violin if you want the system to be quiet.
“Steam?” He asks. “You have a steam boiler? We’ve used it for water systems. Well, I don’t see why it shouldn’t work for steam. I’ll look into it.”
Huh? I’m thinking he has NO idea what he is talking about there. I’ve had both hot water and steam. Very different from my perspective but maybe I’m not giving him enough credit.
Anyone heard of this “new kind of replacement pipe”? I’ve been searching for it and can’t find it.
Edited 1/3/2005 7:47 pm ET by jmo
Replies
bump
CAUTION
Lots of perfectly good steam heating systems have been messed up and ruined by well meaning but uninformed people over the years.
Steam is a special type of system and no plumber or HVAC person who is not trained in steam will know what it right vs. what is destructive.
This is your house so check this out carefully before you proceed. The near boiler plumbing is CRITICAL to proper steam system performance and small, seemingly insignificant details can make the difference between success and failure. "Moving the boiler over two stud bays" sounds like you'll be doing all new plumbing so this is important that you find a specialist in steam to do it for you.
Go talk to the guys at http://www.Heatinghelp.com, they are the steam guys.
thx,
Norm
I feel I should elaborate a bit, in case I sounded harsh in the last posting:steam has no moving parts (essentially), all of its function is controled by vapor pressure and gravity and heat. These things you can not see, so they are difficult to intuitively grasp. Special training exists solely for steam HVAC contracting but is not widely available or widely used (due to relative rarity of surviving steam systems, of course). Lots of the functioning portions of a steam system will look like something you are familiar with and can easily make mistakes about (like steam traps in the outlet of a 2-pipe radiator can look just like normal black pipe Ells, but have carefully designed orifices cast inside them, without them the radiator won't even work).The reason why steam systems are this way is because they were created during a time when electricity did not exist. So no motors, pumps or any other controls, that we take for granted in this day and age, are used. Hot water systems are great (and relatively easy to design and maintain) because they use a pump and a manifold to control the function so the boiler and gravity can be nearly ignored. One question to ask yourself, as you sound like you're gonna change so much of your system, is what about converting to hot water at this stage?Advantages of hot water over steam: radiant floor heat is possible (the very-most even and efficient heat source), and water temps can be lower and can be adjusted with seasons to reduce energy use. Hot water can be pumped over and around things, into new additions and rooms currently lacking heat. A radaitor full of hot water is less likely to burn a child than a 212F radiator full of steam. Hot water can be run 24/7 so the rads all stay warm (steam is cycled so about 2 or 3 times / hour the rads will return to air temp, meaning that the room may feel quite cold in between steam cycles - and steam systems cycle much more slowly than forced air systems do).Advantages of steam over hot water (and especially over forced hot air): steam and hot water are radiant heat systems, so the objects in the room are warmed, not the air. The air in a radiantly heated room can be quite cool, but you and the chair and the towel your use after your shower will be comfortably warm. This feels nice, and also allows there to be more humidity in the air accessible to you (heated air with the same moisture content will be dryer, RH-wise than the same air at a cooler temp). I think that steam, because the radiator is hotter than a hot water radiator, will do this the most (the room air is cooler and the towel hanging on the wall across the room from the radiator gets warmer, faster).In all types of systems there are pros and cons, just throwing out my 2cents.Hope this stuff helps,
Norm
Norm--
This is great information, thanks! I've had hot water and steam, and really know more about the hot water systems. I'm enjoying learning about the steam.
We're really only moving the pipe for one radiator (someone in the 1930's "reorganized" the second floor of our place and the radiator ended up in a closet with no radiator in the bathroom. Not the strangest thing about the house, but up there.)
95% of the pipes in the system won't be touched. This pipe isn't connected to any others all the way back to the main in the basement. We have 9 more radiators in the house. Converting the whole system to hot water, including the replacement of every single radiator to a two-pipe system would be a massive overhaul that we can't afford. Ah well. I'm beginning to really like the steam. As an ex-MET grad, I like the physics of the thing.
If nothing else, I'll get our regular steam guy back to do the job and pay for it out of the funds that the plumber won't get. No worries.
Thanks much!
Edited 1/6/2005 1:21 pm ET by jmo
Norm, most of what you said is close to being right. But a few thigs were not.
"..steam and hot water are radiant heat systems, so the objects in the room are warmed, not the air."
Not true, though, typically called "radiant floor heating" and devices called "radiators" exist in both systems, the heat transfer to the space and the occupants is mostly convective.
"This feels nice, and also allows there to be more humidity in the air accessible to you (heated air with the same moisture content will be dryer, RH-wise than the same air at a cooler temp). I think that steam, because the radiator is hotter than a hot water radiator, will do this the most (the room air is cooler and the towel hanging on the wall across the room from the radiator gets warmer, faster)."
This, Norm, is complete hogwash. You should be ashamed of yourself for believing and worse yet, dispensing such drivel. A steam system will introduce some moisture into a space through vents and traps. All but the most diligently maintained systems have leakers. Thermostatic vents will leak some before they closeoff completely. The moisture contained in air is not more or less "accessible" to you at reasonable temperatures in a conditioned space. You made this junk up as you were typing, didn't you?
<grin> I have struggled with this too, so here's the deal, as I understand it:Steam heat, or hot water heat, provide occupant warmth by radiation at lower air temperatures so the RH% is higher than when the space is heated by forced hot air.Relative Humidity:
Air at each temperature and pressure has a particular ability to 'hold' water. The quantity of moisture present in air at a particular temp./press. is represented as Relative Humidity, as a %. RH% vs. Temp:
Warm that air and the ability is increased, so the RH % drops (and vice versa). Heating up air makes it feel dryer because the moisture in it is less accessable to your skin and sinuses for comfort. Cooling that air causes the RH to rise until it reaches 100% and then the moisture condenses (like water on the side of a cool beer on a summer afternoon).Warming yourself without warming the air:
If you heat yourself (and your living space) by heating the air (and then distributing that warm air) the air itself will need to be warmer (and so, lower RH) than the air in a radiantly heated room. This is because the radiantly transferred heat is able to warm you directly, without increasing the air temp very much.You are correct that the air IS warmed in a radiant system too, but my point is that this is not the only method of heat transfer. Because the air itself in a comfortably heated, radiantly heated room is relatively cool (maybe below 65 deg, compared to 68 or more for forced air heat), the RH% of that air is slightly higher.I am not meaning to imply that any moisture is added to the air, just that the heat transfer method allows for cooler air in the living space, and that means a higher RH%. No steam should ever escape (in a properly operating system NONE escapes, the vents close by the steam after all the cool air is pushed out).In cold climates in the winter, most of the time, it is necessary to add moisture to the house to keep the RH above 25 or 35% for comfort. So every little bit helps. Norm
SOME of the warmth you feel when near a radiator is due to radiant heat transfer, but most of the comfort from such a system is due to the room air temperature being raised to a comfortable level. I lived with steam heat for years. This is not speculation, but a reality. If you were to analyze the heat transfer from a "radiator" you would find that the largest portion of heat transfer is due to natural covection, not radiation, ceiling mounted radiant panels being the exception. And though no steam will escape from a properly operating system, the volume of air that is vented out every time it cycles is very humid and the system does add a noticeablce and measureable amount of moisture to the air in the space.
Air that contains a given amount of moisture does change in relative humidity with temperature, that is true. But the concept of "usable" moisture being related to relative humidity is ficticious. Inventive and slightly intuitive, but nonsense nonetheless. BTW, air at 30% rh and 65 degF is at about 28% at 68 degF, an imperceivable difference.
"The quantity of moisture present in air at a particular temp./press. is represented as Relative Humidity, as a %. "
No, this is incorrect. The quantitiy of moisture contained in air is the Humidity Ratio (or specific humidity) and is expressed in grains per pound. The fraction of moisture contained in air at a given temp compared to the amount of moisture of the same temperature air at saturation is relative humidity, expressed as a fraction or more commonly as a percentage. Pressure, when dealing comfort issues, is irrelevant.
Thanks Norm...(and Rez for bumping my question up :)
The folks at HeatingHelp gave me enough solid technical questions to challenge this guy. No flex pipe for my system! They'll need to bring in an expert on this (who I approve) or carve that price out of their original bid. I don't think they'll argue. They are very good plumbers who, I believe, didn't understand that they'd be working with a steam system (they are subcontractors for the tile guy).
Here's the answer from HH, for future reference:
New kind of flex steel pipe?
Sounds to me like you know more about steam then he does ;)
I can't for the life of me find it, but Dan Holohan used to have a website with all kinds of great Q&A about steam heat...
Edited 1/6/2005 12:44 pm ET by PaulB