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Cannot get the house warm

First of all, we love your books. Very informative, great writing style.

A few days ago, we started to have the following problem: Room temperature may be 68 degrees; we feel a bit chilly and set the thermostat to 70 or 71. Boiler comes on and after a few minutes, the radiators get warm. Problem is that the temperature only goes up to, say, 69 degrees and the boiler shuts off before reaching 70 or 71. Our boiler is fairly old (40+ years), but for the past few years, we had no problems getting our 1920s colonial warm and comfy. We did not make any changes since last year. Any suggestions where to start? Thanks very much.


  • David Efflandt_2
    David Efflandt_2 Member Posts: 24
    What is actually shutting off the boiler?

    It might help if you said what type of heat you have (1-pipe steam, 2-pipe steam, hot water?). Then you need to determine what is shutting it off (thermostat, pressure, low water?).

    It could be as something as simple as an air vent on a radiator close to the thermostat venting too quickly or not shutting off, heating the thermostat quicker than the rest of the home. Depending upon the type of themostat it might be normal for it to shut off before it reaches its set point to avoid overshooting, because radiators continue to give off heat after the boiler shuts off. Or on a mechanical thermostat, the anticipator (rheostat like thing in it that is actually a small adjustable heater) may have gotten moved, causing it to shut off too early.

    On a steam boiler it could be low water cut-out, or gunked up pressure sensor. When I first bought my home I thought it was normal for the vents to whistle and click loudly when releasing more air. But actually the Pressuretrol was set way too high, because once it cut out on high pressure and the vent damper closed, the vent damper stuck closed and would not reopen until it cooled down. That caused it to shut off early when it got colder and tried to run longer. The pressure gauge was also stuck and port to it plugged up (inaccurate) Replacing the faulty vent damper allowed the Pressuretrol to be set as low as it goes for quieter air venting and improved efficiency.

    While a 40 yr old boiler may not have a vent damper, the point is that something heating the thermostat quicker, or the rest of the home slower (other plugged vents), or something on the boiler unrelated to the thermostat, could be cycling it off early. If not mechanically and electrically experienced enough to determine that, seek professional help.

    I am not a pro, just a 5 yr owner of a single pipe steam system. A properly working steam system with properly sized/working air vents should be more comfortable than scorched (forced) air at a lower temperature.
  • Dave_4
    Dave_4 Member Posts: 1,405
    To over-simplify...

    It's either the thermostat, or the boiler control(s).

    Simplest way to find out is to jumper the two wires that go to the 'stat - either by pulling the 'stat off the wall and simply 'touching' the two wires for a time and see if the samwe problem exists. If so, it ain't the 'stat - head downstairs...

    If the 'stat cannot be easily pulled from the wall, somewhere near the boiler 'stat wire has to drop in and enter the cabinet. If you know you have the right wire, simply diconnect it at the joint between boiler wires and 'stat wires going thereto - and, attach one leg to the other. A tiny arc may be seen. That's okay. Leave them clipped together and see if the boiler runs and runs and runs until ypu overshoot the desired temperature. If that is possible, the 'stat's to blame.

    Of note; the internal thermostat (better known as an aquastat) that prevents the boiler from OVER-heating, may be whacked - preventing the boiler from making the water hot enough to meet the setting of the 'stat.

    Once you determine which issue is the culprit, we can dial-in a proper solution.

    Let us know what you find with the jumpered 'stat wires first.

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  • Rip it out

    convert the radiators with 3/8" pex and have Ken install a Viessmann condensing boiler. Hopefully you don't live in NYC though.
  • zeke
    zeke Member Posts: 223

    Good idea, but your averagr homeowner doesn't have a clue as to which 2 wires to jumper; if they jumper the wrong wires (c to R ) they will burn out the control transformer and then he'll have NO heat.

    Since the tstat seems to be calling for heat why don't you simply raise the setpoint temperature to 80 or 90 which is the same as jumpering w to R for your test, Then, if it does the same thing you can rule out the tstat; if it doesn't then change the settings on the tstat or get another one.
  • Dave_4
    Dave_4 Member Posts: 1,405

    You are probably right. I replied as I did because of one thing he wrote. First sentence: "First of all, we love your books."

    This might be terribly jaded, but anyone who read Dan's books, and engaged them with the comprehension suggested by the thread originator - is probably better informed than half of the contractors we know who have NOT read anything at all, much less Dan's seminal steam book(s).

    But I admit, asking a poster to jumper T&T is a leap in faith regarding Martin's abilities. Fact is, it is hard to divine who the posters are. Rhetorically I ask, "It is necessary to validate the competence of the poster before repliying"?

    I assume anyone who asks a question, does so, looking for the answer guys like us can provide. I have to leave it up to the poster as to whether the response is within their comfort level of talent. How else can it work - demand every poster state their level of technical awareness - before answering?

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  • John Cockerill
    John Cockerill Member Posts: 94
    temp rise

    Is your system steam or circulating hot water?
  • Martin Gritsch
    Martin Gritsch Member Posts: 5
    Thank You!

    Thanks for all the replies (especially the super-quick reply at 5:09 a.m.!).

    I am happy to report that the system is working fine again and it is nice and toasty in our house—just in time for the snowy day we are having today.

    A quick summary: We have a one-pipe steam system. The thermostat was fine and the water level was as well. As suggested by you as a possible culprit, it was the pressuretrol that was causing our problems. The screw that lets you adjusts the in-pressure had come loose. Screwing it back into the spring that actually sets the pressure did the trick.

    BTW, I agree with your take on steam heat in general. We are very happy with it and much prefer it to forced air. Having knowledgeable people available who are willing to help online makes it even more enjoyable.
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