Thursday, February 15, 2018

How’s your HVAC, Part 3

In the previous two parts, I showed a simple way to approximate HVAC (Heating, Ventilation, Air Conditioning) enclosures with pieces of diesel shells (see: ). But as correctly noted in comments to the post just cited, in my modeling era (early 1950s), building air conditioning was not yet common. Simple ventilators would have dominated most rooftops.
     It is partly to acquire more ventilators, and a variety of types of them, that I wanted to get one of the Walthers “Roof Details” sets (their number 933-3733). Here is the front of the box for that set:

You can see listed all the different parts, 37 items in all (you can click on the image to enlarge it). Most are ventilators, and only a few are really HVAC enclosures. The set comes with just one of each of the larger items, but there are multiple examples of most of the ventilators.
     To better show the parts provided, here is the illustration on the box:

This shows one of each of the kit items (the building itself, of course, is not supplied). Incidentally, note that with this set, as with any Walthers structure kit, there are PDF copies of the instruction on line. You can just Google something like “Walthers 3733” (the number of this kit) and the instruction sheet will come up promptly. This can give you an advance idea of how the parts assemble.
     Recognizing that in my modeling era (1953), ventilators were much more common than building air conditioning, I assembled several of the ventilators in this Walthers set. You can see some of the styles in the photo above. My only comment about assembling these is that the sprue design is such that even careful use of a sprue cutter will still leave small scars and protrusions on the parts, but a few strokes with a fine-toothed file readily removes them. Shown below are six of the eight styles of ventilators and intake/exhaust parts (there are more of each style on the sprue, just not yet assembled by me). These are right from the sprue, so they still need a coat of flat finish and some weathering.

     These can be positioned on building roofs to suit your idea of what might be going on in particular parts of a given building. After adding a little dirt and rust, using Pan Pastels, I tried out a few of these ventilators on my buildings. As an example, here’s the roof of Guadalupe Fruit in my layout town of Ballard:

     I’m pleased with these Walthers parts, and will build more of the ventilators. This is a big set, and a good thing, too — it’s surprising how fast they disappear when you start “improving” the roofs of various buildings! And though I don’t think I want to place any of the air conditioning units from this set on my 1953 buildings, they may make good loads for flat cars and gondolas. After all, in 1953 air conditioning was the coming thing!
Tony Thompson


  1. That's a nice collection . . . glad to see Walthers offering it. Many of the items though that most folks would assume are simple (gravity) vents are actually rooftop exhaust fans. You can do an internet search for things like "roof top fans", etc. and get results for both manufacturers and suppliers of ventilation equipment. It also gives you a better idea of what the stuff actually looks like. A few manufacturers of ventilation equipment are Greenheck, Cook, Acme and Dayton. And there are several more.
    Roof top ventilators in earlier years where typically made of galvanized steel. Aluminum is much more common these days. Rooftop air conditioners are usually painted steel, with each company having their "proprietary" color (typical colors include light green, light gray and light tan).


  2. If I recall, Oldsmobile placed the first auto air-conditioning system in 1953 on the 1954 Rocket.
    Olds in those days got the first of all GM innovations. When my uncle brought it over for us
    to see, we couldn't see the engine for all the A/C piping. You can park one of these out front with the
    hood open?

  3. I have the Walthers set and turn to it time and again when roofs need attention. I find it useful to spray everything with Dullcoat or Tamiya gray primer, then do an ink-alcohol wash, before assembly. After assembly I do touch-up and weathering. This gives the feeling of saving time because when one structure needs just 2 or 3 details, the whole sprue is already ready.

    Some of these parts are quite large for the typical model building, so care should be taken in selecting them, lest they dominate the roof. Many are best suited for very large industrial buildings, rather than retail stores and the like.

  4. Thanks for these comments. I agree with all of them, and especially Jack's knowledgeable points.
    Tony Thompson