Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

100 year old fan curves

cgw Member Posts: 42
I am looking at a pre-1900 theater. It has two large fans for ventilation (one still has the steam coil - not working). I understand that they still run. One has a new motor. The other motor looks like it could be original. The Theater was built in the 1890's. I can only assume the fans are as old and were built into the space they are in. (at any rate they are at least pre 1930)

The owner wants to add cooling coils to get some air conditioning. I have told them that aside from the physical issues with putting the coils in and sizing issues, etc., etc., that the fans would have to be speeded up. Even if they still work I would not want to think what would happen if the speed were increased.

But... just for kicks and academic interest is there a source for fan curves for 100 year old fans? It may give me an idea of the original design air flow.


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,564
    fan and blower information

    ww grainger's catalog used to have a lot of fan and blower information, so i suppose you could start there.

    in particular, i remember they had advice on silencing air flows for theaters.--nbc
  • Steamhead
    Steamhead Member Posts: 15,329
    edited March 2012
    There's plenty of old info floating around

    but first, do you have a make and model on these units?

    Also, where are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • cgw
    cgw Member Posts: 42

    The make and model are old and older. To be honest I did not even look for a name tag. I do not think I would find one (plus there is no way I would expect to reuse the fans anyway). It is very hard to get around the fan in the space it is in. Plus a good amount of rust, grime and grease. I would heve expected a fan that old to have one of those flat wide belts but the belts were modern (4 or 5 of them). There were some renovations in the 70's. The fans could be newer, say 70 years old instead of 110, but I do no see how they could have installed them after the building was built. The newer motor is 15HP. I did not bother looking for a name tag on the older motor for the same reasons above.

    The fans are in upstate NY.
  • Jamie Hall
    Jamie Hall Member Posts: 18,915
    You can probably come remarkably close

    to the information you need working from basic principles of fan desigh -- and there are a number of texts and handbooks available for that (which, unfortunately, I don't have to hand at the moment).

    You need the following information, as a minimum: fan type (fully shrouded, unshrouded; axial, centrifugal (I presume the latter).  Blade type if centrifugal -- flat, backwards or forwards curved.  Diameter (outside, of eye).  Motor horsepower you have -- so it can't be absorbing more than that (might be less).  Motor rpm.  Fan rpm (get that from motor rpm and ratio of pulley diameters).

    Given that, you can probably come within 20% of the cfm at free discharge, and get a pretty decent idea of how the cfm will vary with pressure and fan rpm, and a fair idea of horsepower required.  You won't be spot on, but do you need to be?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
This discussion has been closed.