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Trying to get a grip on my steam heating system.

riverhawk Member Posts: 2
Hello everyone. I'm impressed with the amount of resources here at Also I'm halfway through "We Got Steam Heat," which is helping a lot...basically I'm learning it is up to me to understand how my steam heat works or face lots of trouble down the road.

Right now I have a lot of work to do, but I'd like to start by getting the right air vents and main vents. Also, I need to get a good EDR calculation since the boiler has a leak and needs to be replaced before next winter. I think there was a lot of fresh water going into the boiler, so I'd like to try and figure out the cause of that before getting the boiler replaced.

The house is roughly 30' x 30' and two stories. It is a one-pipe system. All radiators are Arco from American Radiator. I'm going to be using the specs found on to figure out the EDS (which can be found here).

The radiators in the house are as follows:
floor room tubes height (inches) sections
1 entrance hall 6 32 12
1 living room 1 6 25 12
1 living room 2 6 25 10
1 dining room 6 25 16
1 kitchen 6 25 14
1 bathroom n/a n/a n/a
2 main bedroom 1 4 19 14
2 main bedroom 2 4 19 20
2 second bedroom 4 19 19
I'm not sure about the 1st floor bathroom and need to do a little more research. It is set into the wall and different than the other radiators. Also, I just remembered, there is another small radiator upstairs in the bathroom (this steam heating stuff is pretty demanding!).

I'm pretty sure the main vents need to be replaced. There is a large and small main pipe. From what I can tell and looking over, the large pipe has a Hoffman 75 or 76, and the smaller has a Hoffman 4A.

The air vents are a combination of old vents and some I bought from Home Depot, which really solved a banging problem.

Right now, I'd like to start ordering parts and try to find a good contractor or two who knows steam heat. Reading through some other threads, i thought getting all Hoffman 40's might work for the radiators, and then just replace the main vents with one Hoffman 75 and one Hoffman 4A.

But, as I said, I'm only halfway through "We Got Steam Heat" and still need to learn a lot. So I thought I would ask here for any advice.



  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,479
    Depending on the length of those mains, Gorton#2(‘s) would be a better start, for the same money. Radiator vents with changeable orifices will prevent unused vents from piling up in the spares box, as you finish the balancing of the new boiler, and system.. What are the depths of the radiators? There is a chart here somewhere which can be used to calculate the radiation EDR from which the boiler sizing must be made.
    Doing an overfill test would confirm or deny the leak in the boiler. Or in the wet returns.
    Putting on a good low pressure gauge, (0-3 psi), will help with main vent sizing should you need more.—NBC
  • retiredguy
    retiredguy Member Posts: 410
    For more information on the radiators in your home go to the "museum" page by clicking on "Visit" in the top right hand corner of the page then scroll down to the caption "radiators" and select arco radiators.
  • riverhawk
    riverhawk Member Posts: 2
    edited April 25
    Hello NBC and retiredguy. Thanks very much for the replies.

    I looked up Arco on the museum page and got a great spec page (here). Running through things suggested:
    • length of mains are roughly 30' and 45'
    • depths of radiators are in new chart below
    • also included in chart is heat emission for each radiator
    • will put down overfill test for things to research this week
    • gauge goes from 0-30 psi and pressuretrol is set to 1 psi
    floor room tubes height depth sections heat emission
    1 entrance hall 6 32 7 7/8 12 44.4
    1 living room 1 6 25 7 7/8 12 36.0
    1 living room 2 6 25 7 7/8 10 30.0
    1 dining room 6 25 7 7/8 16 48.0
    1 kitchen 6 25 7 7/8 14 42.0
    1 bathroom n/a n/a n/a n/a n/a
    2 main bedroom 1 4 19 4 3/4 14 22.4
    2 main bedroom 2 4 19 4 3/4 20 32.0
    2 second bedroom 4 19 4 3/4 19 30.4
    2 bathroom 4 25 3 1/2 7 14.0
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