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Main return pipe temperature (in basement near the Vent) How hot?

NancyQueensNY
NancyQueensNY Member Posts: 13
edited January 2016 in Gas Heating
Noob here - but have read Dan Holohan's books on steam heat, so i know a few things to get myself into trouble. Here is the situation:

I have a crown gas boiler for steam heat which was converted a few years ago from oil. I think the main vent was never updated during the conversion. It looks old and corroded and the pipe is barely luke warm when boiler is operating. Is this an indication that air is probably locked at the end of the main line and vent needs to be replaced with a higher venting capacity?

System specs: Crown ~100btu, 11 radiators, 2 family home, 1900 sq ft per floor, basement is heated with pump baseboard and hot water. Boiler maintains ~20 min cycles; pressure guage shows about 1.5psi. Main floor radiators are heating; 2nd floor radiators are intermittent.

Comments

  • JUGHNE
    JUGHNE Member Posts: 8,949
    Considering that it requires the high temp of steam to close an air vent then the steam must not be getting there because the vent is closed and the air is not getting out. Depending upon the size and length of the main you may need more than a single vent at that location. An air vent should burn your hand as the steam hits and closes it.
    NancyQueensNY
  • Abracadabra
    Abracadabra Member Posts: 1,948
    Probably need more main venting.
    NancyQueensNY
  • NancyQueensNY
    NancyQueensNY Member Posts: 13
    Thanks Jughne and Abracadabra. Quick followup:

    1- The steam pressure gauge stays at ~1.5 and never reaches the pressuretrol max, is that normal? Could this mean under-fired burners? shouldn't the system pressure be high if the air is not venting fast enough and lead to fast cycling? (btw, im not experiencing fast cycles, they are consistent at 20min which is how the thermostat is set)

    2- Single or multiple vents - wouldn't the system reach the same equilibrium even with one vent albeit a bit slowly?
  • JUGHNE
    JUGHNE Member Posts: 8,949
    It requires fuel to push the air out of piping before heating can begin. You are very fortunate to have a system that runs that low with out pressure shutdown. Having more air vents allows the steam to move quicker to the end of the main pipes. Over time this extra run time adds onto your fuel bills.
    Good venting may allow your boiler to operate on less pressure and quicker than it does now, less pressure....less fire needed...less money.
    NancyQueensNY
  • JUGHNE
    JUGHNE Member Posts: 8,949
    The old vent you have that only gets lukewarm is probably not opening. The lukewarm you feel is a mix of steam and air being compressed to that point. Again pressure costs you money. If that vent worked then all air to that point would have been expelled and steam would be there......ready to go to work with the air out of the way.
    NancyQueensNY
  • NancyQueensNY
    NancyQueensNY Member Posts: 13
    Any thoughts on why you think the pressure is so low? if there is inadequate air venting out then wouldn't it eventually trip the pressuretrol?
  • Steamhead
    Steamhead Member Posts: 14,840
    It should, but maybe the pigtail under the Pressuretrol is plugged.

    There are plenty of good steam men in the NYC area- check out the Find a Contractor page, which you can get to from the main site.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting