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Mystery of The Cold Risers, Part II

I posted this maybe a month back, and got some great advice. Old thread linked below if anyone wants to peruse.


Steam now definitely gets up the risers, but it doesn't quite reach the top floor before the thermostat is satisfied and shuts the boiler off (I have vented the living daylights out of the north side of the building and downsized the vents on the south side as much as possible). I am up against the last stubborn remnants of the problem, and have a couple of followup questions.

1) I suspect some sludge in the north-side steam supply pipes, where my low spot used to be. Do I just cut them open, scrape/pig/spray them out, then install a union? Is there an easier way?

2) Could/should I also install a threaded wye cleanout while I'm at it? Or is this no good for steam?

3) I have also noticed that my system performs fine if I can just get it to cycle longer. For example, if the thermostat cools off to 69F, then the boiler brings it back up to 72F, the top floor gets heat and everything is fine. My current model (linked below) has no option to do this (it pops back on at 71F and I can't seem to change that) - is there a model that does?


Many thanks for any advice!



    EBEBRATT-Ed Member Posts: 15,307
    Some thermostats have a cycles/ hour setting that you can adjust for longer cycles. Steam lines seldom have sludge but it is not impossible especially if you had a low spot.

    Cutting the pipe apart is difficult but if you really think it is blocked or partially blocked go for it
  • GiantPineapple
    GiantPineapple Member Posts: 5
    @EBEBRATT-Ed hey thanks so much for this. Do you happen to know a model thermostat that does this? I already spent $200 on one where I evidently misunderstood the spec and I'm hoping not to wiff like that again :D
  • Jamie Hall
    Jamie Hall Member Posts: 22,905
    Try a Honeywell/Resideo T87 and spend some time fiddling with the anticipator. You'll get it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England