Currently, I have a 3D printer in my office where I work with a removeable vent that I fit to the window. I'm looking to move it into my basement.

I'm getting an oil tank removed, and with it, I think the crew removing it intends to cut and cap the vent and fill lines that go through a concrete wall to outside the house.

I'm wondering if it makes any sense (or is incredibly stupid for some reason) to let them close the fill line (assuming it's gnarly in there) and throw a filter screen over the vent line (since I assume it'll be cleaner (or more easily cleanable) and attach my current in-line fan to the vent.

I can then basically re-create my window setup, but connecting the 3d printing enclosure to the fan (mounted to the vent) with the goal to vent the 3d printer outside without any fresh cuts in the concrete.

Bad diagram

What I want to ask is the following basic questions:

  1. Can the oil vent pipe be used as a fan-powered exhaust for a small 3x3 enclosure
  2. Does having an exhaust in a room with a propane furnace and a heat pump hot water heater possibly cause CO issues? I've read that having negative pressure out of a room with a gas appliance can cause CO buildup, but I don't have an easy way to vent fresh air into the room.

The propane furnace IS set up with a fresh air intake and exhaust, and there's some kind of fresh air pipe in the corner of the room.

  • How big is the existing exhaust in the basement?
    – Huesmann
    Sep 30, 2023 at 12:58
  • The intake and exhaust run directly into the propane furnace, and it's both pvc pipes are about 3" in diameter
    – StevenPG
    Sep 30, 2023 at 21:19

2 Answers 2


I doubt the vent is much less or more grotty than the fill pipe. The fill pipe may even be cleaner, since oil washed the accumulated crud in it down into the tank regularly, while the vent just sat there and got cruddy.

Major likely issue is needing a different fan, because such pipes are quite small diameter and will cause high back-pressure when used as an air vent. A pipe half the diameter is 1/4 the area, if you have 3" vent and 1.5 inch pipe. If you have a 4" vent pipe 1.5 inch pipe would be 1/7th the area.

A squirrel cage blower deals well with high back pressure, an axial fan much less so, and a mixed flow axial blower lands somewhere in-between. Typical computer fans are axial. I could interpret your drawing as possibly a mixed flow axial, but you didn't specify fan type or duct and pipe sizes, so it's all rather hand-wavy.

You could either sort out what, exactly, is going on with "some kind of fresh air pipe in the corner" which might have been there to provide fresh air for the old oil burner, or you could clean out both pipes (lots of soap and brushes) and do a sealed ventilation with intake and outflow one per pipe. If the fresh air intake is open and functioning, you might want to use both old oil pipes as exhaust vents for the printer, given that pipes are quite small compared to even small ducts. You could run an intake over to the corner with the fresh air intake.

  • This is awesome! The fresh air pipe comes from the ceiling to the floor and then has some sort of collar around it. However, I did feel cool air this morning coming through it. It makes a lot of sense that it was in place for the old oil furnace. I'm going to plan out both options, adding another leg to the pipe for the enclosure, and also doing a fresh air in + out using the existing oil pipes.
    – StevenPG
    Sep 30, 2023 at 16:31

Exhausting the air true 3D printer without fresh air supply will create negative pressure in you basement.

That would lead to incomplete burn in gas appliances and produce CO.

  • So is it as simply as having an available open-air-in to avoid this problem?
    – StevenPG
    Sep 30, 2023 at 7:22
  • Yes, open a window. Create flow. Or use two pipes through the printer enclosure, similar to a balanced flue idea.
    – jay613
    Sep 30, 2023 at 10:09
  • Exhausting a printer isn't much airflow. In most houses, leakage will be enough to make up for that rather than a back-draught on the chimney. But, yes, the ideal thing would be a heat-retaining ventilator rather than a simple fan; that minimizes energy loss to outside while still bringing in fresh air
    – keshlam
    Sep 30, 2023 at 14:28
  • @keshlam Hmm I think if the kind of person who has a 3D printer has $1500 (s)he'll upgrade the printer before buying an HRV 99% of the time. :)
    – jay613
    Sep 30, 2023 at 21:04
  • I'm a counterexample. I grant I may be atypical; I have too many hobbies and look for synergistic purchases, which an HRV for the workshop area would be. And having yhe money doesn't require immediately spending the money; knowing that is how you get the savings to be able to splurge on something stupid occasionally.
    – keshlam
    Oct 1, 2023 at 1:36

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