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Top Floor Radiator slow to heat...........

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I am a contractor working on a 2014 one pipe Steam Boiler (Carrier). It has two dry returns and the two main vents I replaced. Tstat is in the 1St floor Living room (two rads in that room that I have slow down to the slowest setting. Problem is that the top floor, furthest rad, is not heating up fast enough before tstat satisfies. I would say only half the radiator gets hot. Pitch is fine on the radiator, new steam vent on the fastest setting, and there is no obstructions in the shutoff valve or radiator; confirmed after I disconnected it.

I have the pressuretrol cut-in set at .5 with 1 diff. My question is that this older woman who just purchased this home and is in her first season wants her room warmer........

Any ideas? Should I put two vents on the radiator to make it vent faster? I believe I read that once in Dan's book.

Also on a separate issue and something I am not familiar with is one of the radiators which is in the first floor attached closed in porch that has been converted to a tv room many moons ago is two piped and has a steam vent only on it. This rad is different in its style so I know it was done at a later date. She also complains that the radiator takes long to heat up.......

Thanks for any suggestions

Keith

Comments

  • pedmec
    pedmec Member Posts: 975
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    Are you sure that the boiler is running properly. I would check the gas valve to make sure that the gas valve is opening all the way. You could have the slow opening gas valve not opening the second diaphragm and your only simmering at the boiler. Check incoming gas pressure and manifold gas pressure. I wouldn't assume there is a piping issue as its been in place for 100 years.

    Is this a new problem or was it existing?

    Could check size of boiler compare to radiation load. Could be boiler is to small
  • neilc
    neilc Member Posts: 2,703
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    are all the rads adjustable venting?
    big box store adjustable venting?
    (known to be unreliable and aggressive, even at lowest settings)
    what type rad vents?

    you could try slowing down all other rads a bit more to get a bit more steam to that last rad,
    and that speed vent,

    no supply valve in the tv room? if there it's all the way open?
    another speed vent?
    known to beat dead horses
    BobC
  • KeithDoell
    KeithDoell Member Posts: 22
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    All steam vents are Heat-Timer's VariValve

    Gas valve out on the manifold is okay 3.5 on the monometer outlet pressure

    I did measure all the rads but I will do the math and check to boiler size but at this point I am assuming that the boiler size is fine. I will do the calc and look further into that..

    Remember she is the new owner buying the home "as is" so its her first experience....

    One thing to note is that it is a five section boiler. I saw that the boiler could be one supply tap up to 4 sections but 5 and up it should be double tapped.... Obviously that problem has existed since the install but not sure if it is related to the furthest rad not heating up fast enough.... I did see some surging but the ph is correct on the boiler and the water is fine........

    There is a supply valve high on the rad in the open position the return is low with no trap...just a steam vent on that end..
  • mattmia2
    mattmia2 Member Posts: 9,660
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    Water in the mains from surging can slow progress of the steam through the mains among numerous other problems. surging is usually oil in the surface of the water in the boiler.
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    A 5 section boiler will be happier with two risers -- but it the rest of the near boiler piping is good, it won't make much difference.

    One thing as a sort of last resort you can try is to add another main vent -- at the top of that problem riser, before it goes into the radiator. That works better than just adding more venting to the radiator itself, but it's usually a bit of a job.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    BobC
  • BobC
    BobC Member Posts: 5,478
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    Heat timers are very aggressive vents, try turning all of them down as far as you can, at the lowest setting they are still 0.065cfm. leave the slow radiator on a faster setting but it probably doesn't have to be wide open.

    Y ou measured the gas pressure ino the burners, was this with the boiler and other gas appliances running? Once you know the boiler is capable of supplying enough to fill all the radiators I'd clock the gas meter just to be sure.

    https://hvactechhangout.com/home/system-measurements/how-to-clock-a-gas-meter/

    Bob

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • KeithDoell
    KeithDoell Member Posts: 22
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    Thanks for all the commentary. I calculated the req on the rads and it is 375 sqft of steam the specs indicate that it can do 383 sqft net.

    Also, all the asbestos was removed and none of the main steam pipes in the basement are insulated. Do you think that would help with the far away radiator not heating up as fast as others??

    Thanks for all the ideas
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    No insulation? Do it. It will help. We usually think of insulation in terms of minimizing heat loss -- but in fact the most critical aspect of insulating steam mains is the effect it has on how fast steam can move on initial warmup of the system. And it makes a very large difference.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • KeithDoell
    KeithDoell Member Posts: 22
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    Would you do all the pipes in the basement, that is to say, the dry returns as well?
  • ethicalpaul
    ethicalpaul Member Posts: 5,702
    edited December 2022
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    Sure, insulate if you like but it’s not going to make that radiator heat up faster compared to the others, much if at all.

    You said the radiator gets half hot when the call for heat is satisfied. Forget that for a moment and think in terms of if the room is comfortable. If the room is cold I think you should slow down the radiators near the thermostat. NeilC said this earlier in the thread
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el