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Steam slows down with truly cold weather

I live in a 100 year old 25 unit building with a steam boiler system. Last year the heat was working fine until we hit a really cold spell in February. Suddenly the steam was crawling slowly through the system, leaving the largest radiator (15 sections) in my 1st floor until only half-heating. The steam took far longer than normal to move through the system and all radiators heat slowly & for a longer duration. We had a boiler shut down but it was restarted by maintenance because the auto water cutoff malfunctioned. Then it shut down completely & the boiler guys came out.

During this entire time, I had been telling building management & board that the system was not functioning properly. With the full shut down, the boiler guys replaced the broken pressuretrol, which was one of my suggested malfunction points after I had done some research. The other suggestion was the main vent. Things were back up & running for the remainder of the year.

This year we've had heat on since October and it has been fine... until we hit the really cold snap in December. Same thing is happening again. Steam has slowed dramatically. All radiators in my unit heat slowly and the biggest one never fully heats. I keep getting the suggestion that something's wrong with my radiators, all of which were working fine just a few weeks ago.

We have heat but it's not functioning correctly, which I assume means it is not being efficient & therefore is costing us more in fuel. Can anyone suggest a reason this might happen? Is pressure in the system related to ambient temperature? Can I provide any more information that would help? Thanks to all for the advice.


  • Jamie Hall
    Jamie Hall Member Posts: 22,897
    One pipe or two?

    Makes a big difference.

    Without a lot more information, any answer would really be a guess.  Except for one very real possibility: is something about your particular line subject to cold?  Like... freezing?  If there is a vent or a dry return somewhere out there where it is really cold, it is not unheard of for it to freeze, and that would do it.

    The steam pressure won't change with temperature, and should be low -- no more than 2 psi.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Slow steam

    Is this a 1-pipe, or 2-pipe system? Can you post some pictures of the boiler, and piping, and of the pressuretrol?

    Is there a working gauge on the boiler, and if so, what does it say? Can you tell us what sort of control is on the boiler--thermostat, or Heatimer boiler control?

    Why not get a min-max digital thermometer which will remember the highest, and lowest temps in the apartment, so you can tell the management exactly how cold the apartment has been getting. That way your complaints will have more solidity in the eyes of the building management.--NBC
  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    more questions

    From your original post and description of the problem, you don't ever indicated if your apartment is too cold. You do explain that the radiators behave differently when the weather is cold.

    One thing that occurs to me is this, in a large apartment building, some folks may be too warm and will shut off some of their radiators. Whether 1 pipe or 2 pipe, this will have the same effect of having the steam for the whole building squeezing into perhaps half of the radiators. This will cause the radiators to heat all the way across real fast. In this scenario, that is not normal.

    What controls the steam in the building?
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • rplakefront
    rplakefront Member Posts: 8
    one pipe system

    It is a one pipe system. Sorry, I thought this went without saying since it is steam, not hot water circulation. There is something about the largest radiator (living room radiator, 15 section, largest in my home thus the biggest heat source) that may be subject to freezing. I am above an unheated entryway which I've also been complaining about because the door is not weatherstripped properly and the wind just blows through. So the front of my living room, where the coldest radiator sits, is right over that space. Even now when the heat has just been on for the first time in the morning and is building up from the overnight temp, that radiator is barely heated. This didn't happen in past years though, other than last year.
  • rplakefront
    rplakefront Member Posts: 8

    I will see what I can do about some photos in the next couple days.

    The control system has 4 (or 6?) units on sensor and fires based on the average of those units. In the past we had taken some of the units offline because they had additional heat sources like fireplaces that destroyed the average.

    I do have a thermometer so I know what the temperature is... see more on this below in my reply to Dan. I was board president for years & years & years so they take my observations & complaints seriously. :-)
  • rplakefront
    rplakefront Member Posts: 8
    control & it's not cold per se... yet

    Excellent point, Dave, and you are right. I did not say it's cold because it's not -- yet. But it doesn't work the way it did a month ago and my biggest, baddest, hottest radiator barely works. I can't wait for it to get worse & worse and this exact thing happened last year. As I said to NB-C above, the control system is based on the average of several units. It seems to function correctly. Mine is not one of the units with a sensor and not an outside unit though (as mentioned to Jamie) I do have the unheated entryway below me, which changes the room temp as the season goes on. (Another thing I'm trying to get fixed.)

    So it is not cold but it's not what it was only a month ago. In fact, I had my bedroom radiator off but have now turned it on since function has changed. It is on the opposite wall of my unit, not connected to the living room. When the living room radiator was actually running full on, the temperature at about 7-8 feet up (as high as I can hold the easily perch the thermometer) could rise to as much as 85 degrees. Ridiculously warm, but that's at a peak, in operation moment. That doesn't happen now since things have slowed and the particular radiator doesn't heat fully.

    On Sunday Dec 8, the heat had not been on for 5 hours in the afternoon and it was a 10 degree day. I called our (off site) maintenance manager because I was sure something was broken again. Bless him, he came out and found that it was set to night. He reset & the boiler called so it would be 15-20 min until we got heat. Well, it was more like 30-40 minutes and an hour later the steam was still crawling through. That seems like a very, very long time to me. My unit is not directly under the boiler room but only one unit over so you'd think I'd get heat almost first.

    One more note about the unheated space below me -- it is an entryway thus has a door. But nearly every first floor unit has a unheated basement space below it. In fact all of my unit has that but only this front room has the exposed space with an improperly weatherstripped door. I'm not sure that the "exposed" pipe location makes a difference??

    The operating theory now from the boiler guys is that the vent serving my line/unit (is it one vent per "rise" / per radiator line going up?) needs to be cleaned. The units above me have said that they are cold as well.

    I don't know if I'm really adding more info here. We replaced all the mechanicals in this building during my time on the board, except the boiler. It was replaced before my time here, probably 12-14 years ago. It's the one thing I refused to really learn about.
  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    Overheating in mild weather is a problem too.

    I sounds like you have a system balance problem. Good balance is dependent on fast venting of the mains and risers (if you have riser vents) and slow venting of the radiators. If someone has installed fast vents on their radiators, such as a Heat Time Varivalve (even when set in the slowest position), or other fast vents, it can and usually will throw the system out of kilter. You mentioned that your apartment was cool enough that you turned on your bedroom radiator too. Now, if people through out the building also turn off radiators, it can cause VERY fast heating of the radiators that are "on" during mild weather. What you want in mild weather, is for each radiator to get just a little steam during each cycle. Heating all the way across in mild weather is a problem. The colder the weather gets, the longer the steam cycle will be, and the more of the radiator will get hot. My own building has to have temperatures near zero outside to cause the radiators to fully heat.

    How cold is that entry below your living room? I am guessing that your steam riser comes through that space as a bare pipe? Is the entry 60, or 30? 60 degree space temperature in there should not rob your radiator of its steam, but weatherstripping would still be a good idea for general conservation sake.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • Shooting in the dark

    I would suggest a visit from someone who really knows steam heating (use the find a contractor here). Some weatherstripping is also called for.

    The use of a night time temperature is also complicating matters, as each time the boiler attempts to recover the lost temperature, it has to burn perhaps more fuel than was saved by the lower temperature. A more constant temperature would be more economical.

    I am sure the problems is a lack of balance caused by poor main venting, and that a visit from the right person will correct these problems.--NBC
  • rplakefront
    rplakefront Member Posts: 8
    entryway temp, finding an expert, balance

    Dave, the entryway below my room was 42 degrees on Saturday when I took my thermometer down there to check it out. It falls as the season goes on. I don't know if the pipe is bare or insulated. In fact, I can't quite figure out where it is because we took down the paneling and drywalled that space a while back and I there were no pipes. It must be in the floor/ceiling. I'll have to investigate. Interesting point about overheating in mild weather. We're getting the exact opposite effect of what should be happening.

    NB-C, I agree about finding an expert. Last year I found one and suggested that we start using him, have him do a full system evaluation but it didn't happen. I have made the suggestion again. As for the night vs day temperature, the vendor we use did suggest that we have less variance so we've at least somewhat correct that. But we still let it drop a bit overnight so we have a 6/7 am "wake up" heat cycle.

    I really appreciate all the feedback. I've sent this thread to the board president for her to read.
  • ChicagoCooperator
    ChicagoCooperator Member Posts: 351
    Formerly Heated Entries

    You don't mention it, but something I've noticed in many buildings in Chicago (assuming here from your name that you are up in the far north) is the building entries/stairwells - especially in buildings with an English basement or raised first floor (esp. common in courtyard buildings around Chicago) - is that there were once radiators in these spaces which were removed to "save money" but likely end up making rooms above them too cold. That might be the case here if it's a main building entry. 
  • rplakefront
    rplakefront Member Posts: 8
    heated entryway

    Good point and kind of correct. There used to be a radiator in the landing where the stair turns between the ground and first floor. That radiator was removed a million years ago. The entryway itself was not heated. There are also radiators in the basement storage space that I suspect are not on. I've always meant to have a look at those. The ones in the laundry room ceiling are on & that's the other side of the building which is not having heat complaints. I'll add it to the investigation list.
  • rplakefront
    rplakefront Member Posts: 8
    solution brings more questions

    First, thank you everyone for the help with this question. A service tech came out around noon Thursday and I met with him. First thing he said is the returns are ice cold. The heat had been on around 7/8 am and now at noon it had not been on again so it didn't surprise me. He said "yes, people are cold, the settings are so low." Our night temp was set to 66 and day to 68. One of the 6 units on the sensors, first floor on the other side of building was reading 65. The tech said it's not running long enough to heat your radiators. The average gets satisfied and you never get heat. Logical enough. The board president, who lives on the third floor, said they are warm but agreed to .9 increase so that it would run long enough. Also, there was a bit of rust on the pilot that was causing the boiler to shut down as well so that's cleaned.

    The two units above me (which are not end units with exterior walls) were checked. One has radiator vents painted over so... ya know. But basically it just needs to run longer. We now have heat. However....

    At this moment, I have 14 degree increase in my room temperature from where I was when the radiators weren't heating. Would a point 9 setting increase result in this? It's HOT. Now, I have brand new windows so my unit retains heat extremely well once the heat is actually produced. Other units all have conductive aluminum windows. High temperatures are also in the mid 30s but were in the teens & 20s when we were so cold. We're getting a temperature plunge again so we'll see what happens with that.

    Any suggestions? Would it make sense to reduce control settings to .5 instead of .9? Would it make sense to set them back and see if the problem was more with the pilot rust & ensuing shut down? Does it make sense that I have a temperature rise of 8-15 degrees from a point 9 increase on the control averages? It seems crazy.
  • rplakefront
    rplakefront Member Posts: 8
    i should add

    The vents were fine. New, in fact. Obviously individual unit radiators need work. The tech recommended that we have our maintenance guys go through and put larger vents on radiators for the cold side of the building, smaller where people are too warm.

    He also replaced the vent on my 400 lb 15 section radiator. Might have been a mistake on my part to agree to that. It worked perfectly fine so long as it was getting steam.
  • steamedchicago
    steamedchicago Member Posts: 72
    main vents?

    What are you main vents?  And how long are the mains?  And what sized pipe? 

    Chicago has more than its fair share of knuckleheads who think that a single hoffman 75 is a good enough vent for 200 feet of 3" pipe.  So your mains vent may be working fine, but sitll not be anywhere near big enough.   Inadequate main venting will lead to horrible heat distribution. If you know the length and size of the pipes, you can figure out the volume, and once you know the volume, you can figure out how much they need to be vented.  If that hasn't been done, don't trust anyone who says the venting is fine.  (Particularly someone who wants to use radiator vents to balance a whole building in a way that's better done with properly vented mains.) 

    I'm not clear on whether your unit is one with a temperature sensor, or not, but small changes in temperature settings will let the boiler run longer, which lets the steam get to farther out radiators.  And once they get steam, they'll produce heat, so it can make a big difference in temperature, because the boiler's steam is spread out over more radiators.

     I suspect your slow radiator is at the far end of an inadequately vented main.  If you can't get the management to vent it properly, you can do something about it:  A large capacity vent on the valve side of the radiator.  A vent on that side will close quickly once steam reaches the radiator, so it won't cause over condensing water hammer or "steam robbing". Most radiators have a plugged tapping for such a vent, but getting the plug out can be a bear, particularly if it's got a slot for a screw driver and is installed flush.
  • Don't worry the vents are fine

    Probably your system is under vented. As a result all of residents are paying for 50% extra fuel to squeeeeeeeeeze the air out of some constipated undersized (new) main vents.

    You need to investigate this yourself, or hire a steam pro to do it for you. A low pressure gauge (0-3 psi) on the boiler will soon tell you how much fuel is being wasted by inadequate venting.

    It's time to move from conversation to action on this, so the fuel savings this winter can pay the small price of the venting changes.

    During this time, I would switch whatever control system is now present, to some sort of default settings, or replace it with a thermostat, and sensor in the coldest part of the building.

    Remember that these early control systems were installed as a bandaid for deferred system maintenance, and finally you will be able to solve the main problem.--NBC
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