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Switching Steam System to Warm Water Boiler or Window Heat Pumps?

I own a historic hotel built in 1929 that is all brick and concrete construction, inside and out (<a href="http://www.tiogasuites.com/">[url=http://www.TiogaSuites.com]www.TiogaSuites.com</a>).  It has 2 steam boilers with a 1.1 million btu capacity each that were installed new in 1998.  I never need to use both boilers at once.  The building has 54 units on 6 stories (plus basement) but actually that equates to 92 units when you consider most of the original 12x12' rooms have been converted to 2 room suites.  The units have window air conditioners. 

Even though the portion of the steam pipes that are exposed are insulated, having the boiler on in moderate weather creates enough heat that air conditioners are required.  Plus we had a toddler lean up against a radiator and got slightly burned. I am in Chanute, Kansas and the temperature gets to zero or slightly below on occasion, but even at those temperatures the rooms get very warm with the radiators open all the way.  I was wondering what it would take to convert this to a hot water system that I could reduce the overall temperature during moderate temperatures.  I also have considered installing window heat pump/air conditioners but would have to go with 110v units which are $800 each because I don't have 220v in the rooms.

Since the steam is only at 1 pound of pressure and since our steam pipes are old (we have had leaks in the past), I am wondering if the hot water would be too high of pressure to utilize the existing lines.  Currently I have people using the small portable heaters in rooms if they are a bit chilly before the boilers are turned on which is a bit ghetto for a classy hotel.  Additionally I have put the boiler on a timer so it cycles on and off throughout the night which has helped some.  Of course I have the banging issue on occasion and think warm water would be less of a problem in that regard.  I would appreciate any help you may have!  - Todd

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,471
    historic hotel

    i think the height of your hotel would make the pressures of a hot-water system too great for the old pipes, however there is no reason the existing steam system should not perform much better than your description of it's present condition. after all would the original owner/builder of the hotel have been satisfied with the system behaving this way, when he took posession after construction.

    without knowing every particular yet, i can see the possibility of a new control system, such as a tekmar 279, with several indoor, and one outdoor sensor. in addition, i think the boilers could be staged, by pressure so that in very mild cool weather, the 2 boilers would fire, together to "get up to speed", and then the system would coast along with the single boiler.

    is the system 2-pipe, or 1-pipe? i think the over-heating might be due to over-pressure [are you sure it is 1 psi?], and/or a faulty control system. naturally you can imagine the reaction of that original owner, if he heard any banging at all! some systems at that time were designed for 2 oz!

    how are the fuel costs?

    let us know what sort of system you have, and the means of control, and the information obtained on this site [from 200 cumulative years of steam experience] will get things straightened out!

    remember a picture is worth a thousand words, and may identify a curious component.--nbc
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,471
    more thoughts

    [url=http://www.heatinghelp.com/article/95/Problems-that-plague-ALL-steam-systems/97/Theres-too-much-heat-in-the-building]http://www.heatinghelp.com/article/95/Problems-that-plague-ALL-steam-systems/97/Theres-too-much-heat-in-the-building

    here is a description of some problems with steam systems. this comes from a book available here, which should be in the library of any steam system owner, "the lost art of steam heating" 

    looking at a picture of one of the rooms in the hotel, i get the impression from the shape of the steam trap, that the system may well require much lower pressures than 1 psi to operate as originally designed, but more pictures would show more clearly which type of system it is.

    the aim in your case would be to get the steam to "arrive" at all radiators at the same time.  that is not happening now, and as a result, some areas are overheating. this could be the result of the vents not getting the air out of the pipes,quickly enough.

    why not give us more details of : boiler type, pressure gauge/control type, and main "timer" control,  mfg's of valves, and traps, as well as pictures of any old components still in the building, even though disconnected.

    you will be amazed how well old steam systems can perform-quiet, comfortable, economical, and responsive.--nbc
  • Jamie Hall
    Jamie Hall Member Posts: 15,824
    Conversions

    of this type are rarely cheap, although they can work.  I don't recommend them, and I don't know too many who do.  However, that said, it is quite likely that you have some work ahead of you to get the system working right.  Do get a copy of Dan's books ('A Steamy Deal', available on this site).  Well worth the cost -- you will save that in short order.



    A few thoughts to start with. 

    Pressure.  Should be less than a pound per square inch; most steam heating systems run very well that way.  You may not have the controls to do that; it would help to know what controls you do have on your boilers and how they are set.  In your situation, I would suggest that the boilers be staged (assuming the both connect to the same steam mains); this can be accomplished quite easily with vaporstats, with one boiler set to lower pressures than the other.



    Venting.  Venting is critical to steam heat.  If the air can't get out, the steam can't get in.  It appears that this is some variation on a two pipe syste (which is good -- more on that later!) in which case each radiator has a trap (usually -- there are exceptions) on the outlet which allows air and water out, but stops steam.  If these are not functioning properly, either the air or water can't get out (no heat or very little on that radiator) or the steam can (which creates havoc elsewhere in the system).  It would not surprise me if a number of these traps were not functioning correctly.  It is a bit tedious to go around and find the villains, but it simply has to be done.  That is not the end of the story on venting, though: the air, having gotten out of the radiators, has to go somewhere.  There are several different ways of piping two pipe steam systems, and they differ somewhat in how they are vented.  All of them, though, have main vents on the returns or on the mains or both, and these must be working correctly.



    If the system has ever been run at too high a pressure -- say over three pounds per square inch -- the odds are that the traps and vents are toast.



    Once you have the pressure and venting and trap issues straightened out, you can address the banging -- which may have disappeared completely.  No point in tackling that first.  You can also address system balance at that point.  With most two pipe systems, it is not difficult to come much closer to balance by simply partly closing the valves on the radiators in the hot rooms (don't even try that on a one pipe system).  There are also available valves which have local thermostats on them.  The only problem with those is that the room occupants sometimes mess with them...



    Fortunately, neither traps nor vents are particularly expensive or difficult to repair or replace as needed, even on century plus old systems.



    That's some thoughts for starters...



    Except one more.  You have a potential liability issue which you mentioned: someone getting burned on a hot radiator.  Changing to hot water won't help that.  Although the radiator is "cooler" with hot water than steam, it's still hot; hot enough to burn.  Many schools I have looked at, as well as fancier residences, hotels, and the like, solve the problem very neatly with enclosures around the radiators.  Properly sized, they do not reduce the efficiency significantly, and they do prevent burns.  They are commercially available.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 14,457
    I sure wish you'd posted this in July

    In August I was doing some steam system consulting in Kansas City, and it looks like Chanute is just a day's drive from there.......



    Anyway, these guys are right. What you have looks like a Vapor system, which is ultra-low-pressure 2-pipe steam. When properly set up these are some of the best systems out there.



    The second boiler was probably installed as a spare, so if one broke down you could switch over to the other quickly. This was common practice in the East.



    With proper boiler controls and thermostatic valves on your radiators, you can have a very nice system that won't over- or under-heat.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • TiogaTodd
    TiogaTodd Member Posts: 3
    Here are the pics and I'm learning!

    Attached are the pics I took today of the boilers and a typical radiator setup.  I had an issue with one of the two boilers not coming on so I had a local technician come over and discovered the pressure on both radiators was set at 10# on both units, which of course was way too high.  He set at the lowest setting which is about 2#.  The reason the one boiler wasn't working was because the high pressure switch had tripped.  So tonight I am testing it with the 2#.  Since I have a 2 pipe system and these pressures have been so high I don't know how to look for the vents to replace them as mentioned.  I will definitely order the book!  I have already learned as much in a couple of days on this site as I have learned since I bought the hotel in 2004.  Now I don't think the steam is making it upstairs.  I have had the bioler on for an hour and they aren't getting any heat through the pipes.  Any ideas?  Perhaps it is because the vents are messed up?

    Oh and by the way, I have a steam operated 30 gallon per minute instant hot water heater that was new in 1998 I replaced with tankless hot water heaters in 2004, so if you know someone who would be interested in buying this or a good method to sell it please let me know.  Thanks!
  • TiogaTodd
    TiogaTodd Member Posts: 3
    Vents and Traps

    I wanted to add that I assume the vents and TRAPS are both messed up because of the high pressure.  I had forgotten about your mention of traps.  Any ideas what these look like or where they are located on a two pipe system?  I forgot to mention them to the technician that came by today.  Additionally I am sure part of the issue with knocking is that the radiators are not level.  Even though the floors are concrete and not bowed, the radiators have all been moved and reset over the last few years as new carpet was installed, and I am sure no one paid any attention as to whether they were level after reconnecting.
  • Steamhead
    Steamhead Member Posts: 14,457
    edited October 2009
    This

    is a trap. But there might be other traps that look different from this one, installed in various places in the system. Especially, look at the ends of the steam mains for traps.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Nice Vapor System!

    Hi Todd-  There's a lot of potential in your present steam system.  Vapor steam systems were/are the Cadillac of steam heating.  From what you are telling us it sounds like it just needs some maintenance, a few things straightened out and perhaps some items added to modernize it. Jamie's suggestion on radiator guards/ covers is a good one and he's right you can get a good burn off a hotwater radiator too!



    The extra pressure and overheating is costing you fuel. I imagine you'll be able to see a improvement in you fuel bills with just few simple adjustments. When these systems are properly running they are very comfortable and economical.

    I'm glad to see Frank, "Steamhead" is participating in this thread. He is one of what I call "The Steam Super Pros"  on this board and has a lot of experience in large older systems such as yours.

    Getting Dan's books on steam heating ("A Steamy Deal") will be a big help to you. They're easy reading, humorous, lots of pictures /diagrams and in an evening or two you'll be well on your way to understanding steam heating. After`you finished reading the books you'll know more about steam heating than the majority of  heating professionals. Steam Heating is truly a " Lost Art ". 



    Do you have any blueprints of the heating system?  If not you may want to survey you system and draw out a sketch. I'd wait until you've read the books as you'll have a better idea of what to look for.



    System Improvements-  Boiler Controls- After you get your system operating optimally you may want to look into computerized boiler controls. They have some pretty sophisticated systems now that can monitor the temperature at multiple different location in your building, check  the outside temperature and then set a program to keep you building at what comfortable heat you wish. Here's is link for info for a Tekmar 279.

    http://www.tekmarcontrols.com/literature/acrobat/d279.pdf 

     I'm not suggesting that you use it . It just will show you what is available out there in the way of computerized controls.



    Radiator Controls - TRVs  These are a thermostatic valve which is mounted on the intake pipe to the radiator and can be set to a desired temperature (45 -84 degrees). When the steam system is on and the room temperature reaches reaches the set temperature, the valve closes and doesn't allow more steam into the radiator until the room cools below the set temperature at which time the valve opens and allows more steam into the radiator. TRVs can be gotten with either a radiator mounted dial or with a wall mounted dial ( Like a wall thermostat)



    Trouble shooting - You might inquire around locally where you are and see who might have a thermal imager you could rent /borrow.The house insulation guys use them a lot and they would probably be handy  for troubleshooting  a large steam system as you can easily tell what parts of the system are working and what parts weren't.. I have attached a thermal image of some radiators. You could quickly tell if  a trap that wasn't working. There are rebuild parts available for most of the old traps.



    Your hotel is really a classic!  It looks like a very comfortable place to stay.

    - Rod
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,471
    hotel vapor system

    great pix! i am sure you would benefit from a different pressure control known as a vaporstat. its range is 0-16 OZ.-about 1/10 of the range the old pressuretrol is sometimes running up to now. that plus a good low pressure gauge [0-15 OZ gaugestore.com] will give you the control of, AND the indication of correct pressure. probably each boiler will need its own.

    it is possible that this system has an operating range of 2-6 OZ!  it is also possible that the burner can be modulated in response to the boiler load: 0 degrees outside=full burn; 40 degrees=75% burn, all controlled by pressure.

    it could be that the traps are not working because the pressure is so high. the book will give you an idea as to what to look for in the basement, and maybe the attic, as far as inoperative venting devices. usually these can have their innards renewed. they may not all be bad, but 10 psi is high, for those devices to withstand.

    once the air is being reliably removed, as steam is rising through the pipes, it would be time to verify the means of temperature control. it could be as simple as a good steam-rated thermostat in a place where it is free from outside air. even better would be the outside reset boiler control such as a tekmar 279 which fires the boiler in response to outside temperature swings, and monitors the inside temperature as well.

    i will guess that you will be amazed how such an old system can work so well, when you have worked out all the bugs , in addition to noticeably lower gas bills!!  if you are handy, you can learn how to do much yourself, and you will become fascinated by improving your own system, and by steam heat in general,...as are all of us!!--nbc 
  • Jamie Hall
    Jamie Hall Member Posts: 15,824
    Further thoughts

    Rod has an excellent idea: make a sketch or drawing of your entire system.  Blueprints are, if you have them, a good place to start, but be aware that changes may have been made!  Such as a valve on part of the steam main, or on a riser.  I've seen that, and I've seen it be the cause of no heat in an entire section of a system.  Be sure, too, to note all the traps or other gadgets (if you can't figure out what something is, post a picture -- someone here will know).



    Many systems of this sort have crossover traps at the ends of the steam mains, as Steamhead noted.  They often look much like the radiator traps (they often are the same, in fact!).  They go from the steam main to the dry return, and let the air out of the steam main.  They are very important to even heating.  If they aren't there, then there must be vents at the ends of the mains, to do the same thing.



    Pitch of the radiators on a two pipe system like this really isn't that important, although it's desirable to have the radiator pitch to the outlet.  What is critical is the pitch of all the horizontal piping, whether it's on a radiator outlet or on the inlet, or on a big main or return.  Radiator lines -- both return and feed -- must pitch away from the radiator.  If the feed doesn't, you'll get gurgling (at best) or water hammer (at worst).  If the return is pitched wrong, water may get trapped and you'll get no heat since the air can't get by the water.  On the bigger lines (returns and steam mains) think like water: any condensate which gets into these lines has to be able to get back to the boiler somehow, somewhere.  Trace it out.  If you find a low spot which doesn't drain back to the boiler, you may get no heat in a whole section of the building or water hammer -- or both.  Pipes do sag...  Never assume a pipe is pitched correctly.  Check them all while you're making your sketch with a good level.



    Sadly, you probably do have both bad traps and bad vents; 10 psi is quite enough to do a lot of damage.  You'll find them, though, with patience.



    Carry on and have fun!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,471
    traps

    don't forget to list any mfg's names, or pix of trademarks/logos on these radiator and main traps/vents etc, so your system can be identified more easily. that may point the way, as to  where to look for various components.

    you might want to keep your steam-hot water heater, and use it in the winter only.--nbc
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