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HW rad converted to steam; only heating halfway across

hws
hws Member Posts: 43
I'm working on a 100+ year old steam system. Runs at 0.5-1 psi, all cast iron rads, no steam traps of any kind anywhere, in a church.

I'm told that one of the rads on the system is heating only halfway. I look at it, and it is a HW rad being used for steam service. Not original to the building, installed about 4 years ago to replace the malfunctioning original (the rad itself was purchased used and is actually about 40-50 years old). The vent is on the top of the rad, not halfway up where a steam vent should be/usually is. The church caretaker tells me that it's been like this since it was installed, 4 years ago.

My theory: an older radiator, it might be full of sediment from its previous life as a hot water radiator. If I disconnected it from the system and blew it out with compressed air, maybe this would solve the problem. Have any of you done this before? If so, what pressure would be ideal for this task?

OR, maybe the vent is the cause? I mentioned that it is installed at the top of the heater, not the middle. I'm not entirely familiar with what an incorrectly located vent can do or not do.

Anybody have any input?

Comments

  • Steamhead
    Steamhead Member Posts: 17,387
    Move the vent

    that rad will work fine with the vent in the proper place. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • hws
    hws Member Posts: 43
    drill and tap

    Steamhead, have you ever ever drilled and tapped a cast iron rad? Cast in my experience is brittle, don't want any unfortunate incidents. is there a technique to it.

    I'll need to make a new hole in the heater to correctly place the vent
  • Steamhead
    Steamhead Member Posts: 17,387
    We do it all the time

    usually there's a boss in the cast-iron for this purpose. Don't remember the drill size at the moment, but it's whatever you use for a 1/8" NPT tap. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    5/16"

    or 8 mm, if you're into that kind of thing. :-)
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
This discussion has been closed.