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Air vent for improvised tiny "radiator"

We have (in addition to a heat mat) an improvised radiator in our bathroom. There wasn't room for a real radiator (without removing baseboard), so a past plumber improvised a single (1.5") pipe with an air vent at the end. (We call it the dachshund.)

The dachshund has never generated a ton of heat, but it did get warm in the past. The heat mat (electric radiant) under the tile floor keeps the room comfy but I've recently noticed that the dachshund never gets warm. When the other radiators are hot, it remains cold.

The supply pipe (one-pipe system) is warm coming up out of the floor. So I am thinking maybe the air vent needs replacing (not that old, maybe 5 years, but...). So, what size to get? Is bigger better (i.e. C, D, or #1)? It's possible that our new steam boiler is a hair undersized (we will insulate any exposed steam piping in the basement) and the dachshund is far from the boiler.

Thanks for any advice.

Comments

  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,756
    You can't really go too big on the vent. A small "radiator" like that isn't going to prematurely satisfy the thermostat. If it's on a long runout you need to vent all that air through the dachshund before it can get to work.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,162
    @DyedInTheWool

    I don't agree the water has to get back out. If you vent too fast you can get water hammer. The steam can come in too quick for the water to get back out I would replace the vent since it used to heat and now doesn't but you may have to try different vents. Maybe you can swap the bad vent for a working one on another rad temporally to try it
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,348
    edited November 2021
    Always a good diagnostic tool @EBEBRATT-Ed... to use a "Known Good" part that you have to test a part you believe to be defective. @DyedInTheWool Put the (alleged) defective vent on the rad you removed the known good, then fire it up. sometimes the defective vent will become "unclogged" with the simple fact that you removed it, so don't be surprised if it works on the radiator and the other vent works on the dachshund. Stranger things have happened. But chances are the bad vent won't work and you will be sure that you found the problem.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,756
    I used to have a Gorton #2 on the 24" fin-tube unit in my bathroom, and it never hammered. We're talking about a few inches of 1 ½" pipe here. How much water do you think it's going to be returning?
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,162
    @Hap_Hazzard
    just saying it is a known thing if you have a radiator, especially one that isn't piped the best way and it hammers slowing the venting can solve hammering and water spitting issues. Sometimes the piping is concealed like a second floor rad and you cant access the piping to fix the pitch
  • DyedInTheWool
    DyedInTheWool Member Posts: 2
    Thank you all for all the insights and suggestions!