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uneven steam heat

paul_81 Member Posts: 27
New boiler in old piping system with two steam supply mains. One side heats well, the other hardly at all. We replaced all of the radiator vents as well as a main vent in the crawlspace. How can we tell if the main vent is working properly?


  • Is there a vent

    at the end of each main? How long is each main, and what pipe size? What make and model vent is on each main?

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  • paul_81
    paul_81 Member Posts: 27

    The "good" main wraps around the basement, about 50 feet with two turns. It starts as 3" and end up as 2"? It is wrapped with insulation and has the original main vent(don't know the make) at the end before it drops for the condensate run back to the boiler. The "troubled" main runs through the crawlspace, which is colder than the basement, probably about 50 feet as well. The main vent we just put in is a Dole QV#5, which is piped into a 3/4" swing joint at the end of the main just before it drops for the condensate return. We also have put adjustable vents on the radiators, setting the "good" side to slow and the "troubled" side to fast.
  • paul_81
    paul_81 Member Posts: 27

    Yes both mains are insulated w/ typical asbestos wrap. Troubled side has three radiators off 2 branches. When we first met this system, the second radiator of branch didn't work. In the crawl where foundation work had been done before, the wrap had been removed and also the pipe was left sagging w/ wrong pitch, and probably full of water. We supported the pipe back in its original position. It is mostly wrapped w/ Armaflex insulation.
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