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New to Steam, Lots of Questions!

We recently bought a house that's around 100 years old. When we did the inspection it was in the summer and we never thought to test the heating. I've only ever had forced air heat so the world of steam heating is completely new to me but I've really enjoyed learning about it so far.

Now we're dealing with temps in the teens in NJ and trying to figure out why we can't get certain rooms to warm up.

Here's what I've learned about our system so far and keep in mind I know very little so some of my terms might not be right.

The boiler is less than two years old, Weil-McLain running on natural gas. This is a two-pipe (possible vapor) system with 7 standard cast iron radiators as well as floor boards in the kitchen and a newer extension to the house. The radiators had Hoffman modulating vales on the supply and Hoffman No 8 valves (which look like steam traps) on the return. Some of the radiators also had air vents on the return side.

The radiators furthest from the boiler have a hard time maintaining heat set at 68, and of course this is the baby's room that we need to maintain heat. We had our usual plumber come out to take a look. They plugged the air vents, installed new valves and Hoffman 17c steam traps on 4 of the radiators. So now all the air vents have been removed expect for the one on the extension that I was told had to be there cause that's just a one pipe radiator.

The radiator that wasn't working from the start is still not maintaining heat, and now the others are struggling to get hot. Except of course the ones that were not touched by the plumber at all.

Doing some reading on here as well as the Lost Art of Steam Heating, I figured there might be air in the system that is preventing the steam from getting in the radiators.

I called the plumber back and asked if there should be an air vent somewhere on the main return. He said there doesn't need to be cause that's what will get hot and heat the radiator. After hearing that, I called another plumber who said the setup I have with seemingly no air vents is the only thing that will work with my system and I just need to crank up the pressure to get to the other rooms to heat properly. I tried this and it worked, but was pushing close to 10psi which didn't seem right so I cranked that back down to 0.5 cut-in, 1.5 cut-out.

I looked all over the basement and boiler room for some kind of air vent and came across what seems to be a cross over vent at the end of one of the mains. So I'm assuming this must be some kind of vapor system but I don't see any signs of a differential loop near the boiler. If that's the case, it should be able to run well at very low pressure so even more reason to keep that low.

Can anyone here help point me in the right direction or maybe have a recommendation for someone who actually knows steam in the northern NJ area? I'm attaching pictures of the components I've mentioned but happy to take more as needed.


  • pecmsg
    pecmsg Member Posts: 4,861
    Calling @EzzyT
  • EzzyT
    EzzyT Member Posts: 1,295
    @Tom_Phillips you can reach me at 2018878856
    E-Travis Mechanical LLC
  • BobC
    BobC Member Posts: 5,478
    Your plumbers don't understand vapor steam systems. That was installed as a vapor system and they should run at very low pressure, high pressure is not good for the traps and vents and will burn a ton of fuel.

    There has to be a way for air to get out of that system, are you sure there isn't an air vent somewhere in the basement?

    Call Ezzy, he knows steam and will get the system working the way it should. Also by some of the books offered on this site so you better understand how that system should work. "We got steam heat" is a good primer but with a system like yours I'd get "The Lost Art of Steam Heat", they are both very readable (The lost art is the bible of the industry) and will get you up to speed fast.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    edited January 2022
    Not sure if the air vents were supposed to be there. But they likely were helping not hurting the current situation.

    I suspect that crossover trap had failed so steam isn’t filling the main as fast as it cant vert air as quickly.
  • Steamhead
    Steamhead Member Posts: 16,842
    @Tom_Phillips , from what I can tell this is a Hoffman Vapor system. From the looks of the radiators it was installed prior to 1925 or so.

    This system more than likely had a device called a Differential Loop (or the earlier Equalizing Loop) mounted somewhere near the boiler. Mounted on or near the Loop was the main air vent for the entire system. All the air from the crossover traps and radiators vented back thru the dry (overhead) return lines to this vent. If you can locate the Loop, post a pic. If not, see if there is a vent on the dry returns near the boiler, and post a pic of that.

    If there is no vent, the air cannot leave the system so the steam cannot get into the mains and radiators.

    Your situation sounds like what I found here:


    The good news is, @EzzyT is one of the best steam guys around, and he can fix you up.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Tom_Phillips
    Tom_Phillips Member Posts: 2
    Thanks everyone for the help and the quick replies!

    Ezzy is definitely the man for this job and was able to diagnose some of the (many!) problems after a thorough analysis of the entire system. All the previous attempts were just trial-and-error patches that didn't address the underlying issues.

    It's now clear that the previous owners wanted to spend as little as possible with the new boiler install and did not do things right for this type of system. There is no sign of a differential or equalizing loop so the assumption is it was ripped out at some point in the past, maybe when the new boiler went in.

    If the loop was removed, the air vents on the rads made sense since it probably helped them heat up, but didn't solve the actual problem.

    @Steamhead yes, very similar to the problem you linked to. In my case there are just no vents on the mains at all, so air can't get out of the system.

    I fell confident that we're heading in the right direction now and will provide an update once the work has been completed.