Baseboard vents to nowhere

Hvac_artisan

I’m in the process of purchasing an old building approximately 100 years old with hot water radiant heat big old cast-iron radiators throughout. It is a storefront/shop With an apartment upstairs. In several rooms at the apartment there are vents cut into the baseboard. When removing one of the vents to check where it went it appears to go off the wall towards the attic with just the lath and plaster as a chase. I don’t know of any reason why it would’ve been installed since it is not connected to any mechanical ventilation means. Has anyone else seen this in old buildings or know why this was done?

Jamie Hall

I've seen it, but more often with a small radiator inside the vent. Warm air rises -- and they provide very effective (perhaps too effective for modern standards!) ventilation.

Steamhead

@Hvac_artisan , I think @Jamie Hall nailed it. I've also seen these vents with small gas burners in them which provided the draft, but obviously not in lath-and-plaster chases!

Where is this building located? Do you know when it was built?

JUGHNE

Possibly could be fresh air inlet from the attic.
If you get into the attic, the top wall plates may be cut away and perhaps boxed up above lath and plaster, screened to avoid critters. (but maybe now plugged to avoid the cold draft).

While in the attic you might see the expansion tank connected to the heating. Often a small insulated room was built around them to prevent freezing. The overflow may go out the roof or come down to the basement drain system.
Or the tank was placed in a closet as high as possible.

Hvac_artisan

@Steamhead The building was built around 1890. It’s located in Delavan Wisconsin. It definitely could be something like that because the building was constructed as a plumbing shop originally. so anything is possible

Steamhead

Interesting- I've actually been through Delavan, coming down I-43.

For an example of some of the things they did in Baltimore around the time your building was built, go here:

https://forum.heatinghelp.com/discussion/151036/lovely-lane-methodist-church-a-steam-heating-museum

There were several heating equipment manufacturers in WI back in the day- O-E Steam Specialty Co and Sterling were in Milwaukee, and Trane (which makes A/C gear today) was/is in LaCrosse.

Post some pics of the system when you get a chance- boiler, some radiators, etc.

tomhaeussler

I have seen old gravity systems like bill has described and one of them had the tank and over flow pipe in a very small enclosure in the attic and they had a vent to bring warm air from the house into the enclosure to keep the tank from freezing this was in a very old house in Michigan

Bill_Kitsch69

Likely there are, or were radiator boxes (wood, or metal) at basement ceilings that temper fresh air intakes, ducted off the tops of the boxes to rooms, as you see in your home. This continuous supply of fresh air displaced "bad air" - a nebulous term - as it was believed, in the home. This may be a carryover from a since converted, or replaced steam system. Doubtful it was originally a hot water system, buy maybe. Hot water vs steam heat started really catching on around 1900.. I'd love to see pictures of piping, boiler, and basement ceilings.